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Testing a tuned Tech Force 97

by B.B. Pelletier

Guest blogger
Vince rebuilt a Tech Force 97 and offered to let Herb test it. This report is the result of that test. If you’d like to write a guest post for this blog, please email me.

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Testing a tuned Tech Force 97
by Herb

Courtesy of Vince, I’ve had an opportunity to play with a .22 caliber Tech Force 97. According to Vince, this is a version of the standard Chinese QB36-1. Neither rifle is sold by Pyramyd AIR. It’s been fun and quite a surprise for me.

I’ve just been playing with lots inexpensive guns, trying to find one that I like. I bought a couple for various “experiments.” Like most neophytes, I have now bought and tried enough inexpensive guns to determine that you get what you pay for. Actually, I’ve proven B.B.’s corollary–“You don’t get what you didn’t pay for.” So, there isn’t a $100 gun that really performs as well as a $1,000 gun. At this point, I wish that I had just bought a Benjamin Discovery at the start, but that’s how we all get educated–bad decisions.

Impressions of the rifle
The wood seems nice for a $100 gun. In this price range, plastic seems to dominate. Call me old-fashioned, but I like the feel of the wood on the TF 97 better than the synthetic stock on the Crosman G1, which I also have. I really liked the feel of my cheek to this rifle. It was just a perfect height for me with the scope. Although the TF97 has the same length of pull (LOP) as the Benjamin 392, the right-hand grip is sort of blocky and a bit large. The uniform extension of the forearm makes the gun nice to hold.


On the right, the Tech Force 97. Compare the length of pull and the shape of the pistol grip to the Benjamin 392 on the left.

The front sight was sheared off when Vince shipped the rifle to me. The front sight is obviously cast, then finished with a bit of machine work. The damage was not a big deal for me since I wanted to scope the rifle anyway. Even though there is a parts diagram in the rifle manual, there isn’t any place listed to buy the parts. Vince told me that there is a dealer that sells parts for the rifle, so the diagram does come in handy.

The front sight has three removable parts–two hollow ferrules and an aperture disc. It seems like a nice sight. I’m uncertain if apertures may be bought for the sight, but it would seem simple to make some of your own. A nice fiberoptic front sight and a peep sight would seem to be a very interesting possibility.


Front sight of the TF 97 was damaged in shipping.

The rear sight seems to have quite a bit of adjustment with a very simple mechanism. I assume that the same rear sight is used on other Tech Force rifles. I wish the rear sight on my Benjamin 392 was this adjustable. Why doesn’t Crosman spend just a tiny bit more and put better sights on the Benjamin 392/397?


TF 97 rear sight has lots of adjustability.

I did notice scratches on the cocking lever where the linkage has rubbed the stock. I can’t really tell if the extension of the stock is warped or if the metal parts are slightly crooked in the stock, but the left edge of the forearm rubs the cocking lever. I didn’t notice the rubbing when cocking the rifle. Again, for a $100 gun, you can’t expect super-fine master craftsmanship.


Scratches on TF 97 cocking linkage.

I like the notion of having a fixed barrel. I think the fixed barrel removes a source of error in shooting, and any error reduction is a good thing.

Adding a scope
I used an 8-inch 4x Beeman scope on the TF 97. It was the scope that originally came with my Beeman RS-1. The short Beeman scope ends right at the end of where the breech opens. This made it fairly easy to load pellets with the scope on the gun. I also ordered a CenterPoint scope for another pellet rifle, and it’s a full 13 inches long. Had I installed it, it would have covered the breech, making loading very difficult.


Scope shown above the rifle is obviously too long. The objective bell hangs over the loading port, making loading difficult.

Newbie lesson on ordering scopes
Here’s a lesson for the newbies (like me). Even though all the scopes look the same size on the website, check the scope’s length and weight before you buy. The CenterPoint scope, which I ordered for another gun, is much larger than I had expected. I didn’t even open the packaging. Pyramyd AIR is willing to take back the scope for a full refund, but I created the problem when I ordered it. The length was given on their website.

Loading the TF 97
I loaded with the gun pointing straight up to balance the pellet on my thumb. Even though the TF 97 has an anti-beartrap mechanism, I held the cocking level with my left hand as I loaded a pellet with the right. I was careful not to pull the cocking lever all the way down with my left hand, but held it firmly at a loose position in the cocking stroke. I don’t want the cocking lever bouncing on the anti-beartrap mechanism. The thought of getting a thumb stuck in the slamming breech is unnerving. With this rifle, take the simple extra precaution of always blocking the cocking lever while you the load pellets.


I hold the cocking lever while loading to prevent the sliding compression chamber from moving, even if the anti-beartrap mechanism should fail.

I had trouble a couple of times when cocking the rifle. The rifle seemed to be cocked, but I couldn’t get the beartrap release to disengage. I then started cocking with a bit more authority, and the problem rarely occurred. Being able to get the gun partially cocked did nothing to bolster my confidence in the anti-beartrap mechanism.

Shooting the TF 97
The action has a nice solid thump. It doesn’t seem as hard as the Crosman G1 or the Beeman RS-1 that I have. I’m guessing since this isn’t a magnum trying to propel the pellet at the speed of light. The kick and recoil are somewhat subdued. The lower power level also makes cocking fairly easy. With the short cocking lever (about 14 inches), a magnum-power spring would make this rifle very hard to cock.

Vince also shared with me that the TF 97 has a leather seal on the piston. I guess a synthetic seal would require higher machining tolerances than this rifle has. Leather seals work and were used in a lot of airguns for a long time, so old technology isn’t necessarily bad technology. The leather piston seals do need a lot of oil (this rifle smokes), but I never had a detonation. I assume that the modest power prevents that.

I tried shooting on a benchrest with the gun balanced at the balance point, on the end of the wooden forearm and by the band at the front of the barrel. There was some impact point variation with the holds, but it didn’t seem to be particularly bad. I don’t have much experience judging the hold sensitivity of springers, but I think the modest power kept the rifle from being too jumpy.

My biggest surprise? I really liked the trigger. I have no idea of how the trigger was before Vince tweaked it, but now it’s sweet. It’s the nicest one I’ve tried. It just seemed nice and crisp to me. A gentle squeeze and the trigger breaks. POW! Wish my Daisy 22SG was as nice. I’ve shot only cheap airguns, so don’t be shocked that my standard isn’t the two-stage Rekord. I don’t know if I can afford to try one. If that gets to be the gold standard, like JSB pellets, this pastime is going to get even more expensive!

Vince also said he had cleaned the barrel before shipping me the gun. No surprise that JSB Exact Express pellets seemed to be the best of those I tested. The TF 97 doesn’t shoot quite as well as my Daisy 22SG. With JSB Exact Express, 6 shots went into a less than dime-sized hole at 10 meters on Gamo Paper Targets. I like them because the center white spot is about quarter-sized, and the bold numbers make a good reference for the scope crosshairs. I won’t claim to have the artillery hold down perfect, so the TF 97 might do even better in someone else’s hands.


Six-shot group with JSB Exact Express pellets at 10 meters.

Ordering JSBs from Pyramyd AIR is getting to be an expensive habit. How come no gun shoots the best with the cheap Walmart pellets?

In the table below are the chrony values that I obtained with the Alpha Master Chronograph. I can’t explain why the 14.3-grain JSB Exact Express pellets don’t follow the general curve of the other pellets, but I double-checked the values and they seemed consistent.


Average velocities for several pellets in the TF 97.

All-in-all, this has been quite fun. My impression is that the Tech Force 97 a nice plinker. Since the power seems a little low for hunting (but about the same as my favorite Daisy 22SG), I’d buy the .177 instead of the .22. The groups aren’t PCP target-gun size; but for some good, plain fun, the rifle seems like a nice buy. With leather seals and a modest spring, this gun could easily be maintained for a long time. A little creativity in making some front sight apertures, a cheap rear peep sight and this might be a fun starting target gun too. Just remember to ALWAYS block the cocking lever when loading pellets!

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

81 thoughts on “Testing a tuned Tech Force 97”

  1. Herb, nice write-up. But keep in mind that with a lot of sliding-cylinder guns (and a breakbarrel like the MP513) it is possible to think the gun is fully cocked when it is not. The ‘not quite cocked’ phenomena you ran into can happen on a $600 Diana 54.

    The thing that I DON’T like about this anti-beartrap is that it’s all internal to the gun. Unlike the mechanism on the QB88 or the Diana sidelevers the shooter cannot see it operate and visually check if it is engaged.

  2. Vince,

    Hope about posting your write on the rifle? Since it was on the internals it would really compliment what I wrote.

    Agree about bear trap. Although an injury is unlikely, blocking the cocking arm is an easy way to avoid problem. Sort of like belt and suspenders.

    Thanks again for the chance to play with the rifle. I was really surprise how much I liked it.


  3. Nice guest blog–I’m an editor, and I like clear writing.

    My off-topic quesion:

    My Daisy 953 with a red-dot optic is really accurate at my basement 15-foot range distance. No surpirse.

    I took it to a 50-foot gun range, and with no sight adjustment, it hit about 4″-5″ high, although had consistently tight groups.

    Am I correct to believe the 50-foot distance is at some point higher in the pellet’s arc relative to the 15-foot sight-in?

    I’m trying to convert B.B.’s lessons on sighting-in a scope to sighting-in a red-dot.


  4. Leon,

    Yes, you have discovered the problems associated with sighting in for a close range.

    What you have had to do to get the pellet to strike the dot at 15 feet, is angle the dot downward on a severe angle. The dot keeps going straight out to infinity, but because it is angled downward, the pellet APPEARS to rise as it travels farther. And 50 feet is about where the pellet will top out before starting downward again, given the velocity of the 953.

    Sighting a dot sight is identical to sighting a scope.


  5. Herb,

    Good report — I think you did an excellent job.

    I like the trigger, also; it’s a simple single-stage design, but once it has smoothed out (or been worked on a little) it is fairly light and crisp.

    I suspect the rifle comes new with one extra post and bead front sight insert, as my QB36-2 did. The rear sight is as good as you say in use, but there is a weakness: the spring tension that is constantly on the mounting block (floating at the rear) can cause it to flex; on a QB88 with the same sight, the block actually started to crack.

    I agree with Vince about the partial cocking. The way its set up, the anti-beartrap engages before the sear, so that — I assume — the piston is locked even in case of accidental trigger pull/sear slippage.

  6. Herb & Vince,

    Thanks to both of you for making this review possible.

    One more positive testimony in my mind for Vince's ability to make a gun all it can be with his tuning abilities.

    Well written Herb. Thanks for the contribution.


  7. Herb,
    Nice report and good photos.
    The anti bear trap on under and side levers will always be an issue, I guess. Vince’s comment on expensive guns having the same issue is right on. I had a friend and his 16 year old son over, neither with airgun experience, and it took both of them several tries to get the feel for the side lever cocking on my 54. It is rather awkward until you get the hang of it. Now that I think about, it my cheap gamo break barrel would have been a better gun to try first. I wanted to show them the “nice” gun, but really should have shown them the “easy” gun first.
    Again, nice job.

  8. BB, I’m plinking with “fair” accuracy, but I can see some pellets do better than others in my rifle. I intend to get a tin of Crosman Premiers and a tin of JSB Exacts to try in my rifle(Thought I’d try these because all I have are anything but dome-tip pellets). Do you think accuracy might increase with (what appear to be) a pellet known for quality? I’m not assuming there will be a change, just asking your opinion on the odds of better accuracy based on these two pellets. JP

  9. I won’t assume a change, but I was thinking of trying them anyway. Hey, I see that Pyramydair’s got a few sampler packs available for pellets (something I was kind of looking for). I’ll probably throw one of them in with my order. Anyway, thanks for the odds. JP

  10. Kevin,

    I must jump in and second your appraisal of Vince’s skill level!!

    Folks, this guy is real sharp, and highly skilled..
    Just got back the last batch he worked on for me..
    The Markham that he put 499 barrel in, and made the sight for, and made it shoot.. not just shoot, but shoot great.. better than new, I would guess!!

    A couple of parts guns, a CZ and unknown Russian springer I sent, he rebuilt instead, and they shoot as good or better than new.. cracked stocks fixed as well..

    He thought of a great way to get a Mendoza peep sight on my Diana 27, that had no scope rail, with a simple homemade clamp around the spring tube, no damage, but now I can play the long distance bucket game with ya all.. and no damage has been done to the collector value of that prewar 27..

    Vince is just plain smart and good at fixing airguns.. any kind of springer, it seems..

    That Tech Force 97 was junk when I sent it back to the factory.. they sent it back to me “fixed”, but still junk.. I told Vince to just give it away, since I thought there was no hope for it.. but he fixed it, then gave it away.. again he surprised me!!

    Ashland Air Rifle Range

  11. Leon,
    Your comment:
    ‘By the way, despite my stand on “assualt weapons” (which I take to mean fully auto weapons that have little or no recreational value…’
    makes me wonder if you have ever shot a fully automatic weapon.

    There is a wonderful opportunity to do that coming up in Kentucky the weekend of April 4th at the Knob Hill gun range south of Louisville. It is a spectacular event with awesome machine guns. For about $30-$40 you can shoot about any machine gun there and there are many WWII and current guns available. And, they are all fully automatic. You can also buy one there if you so desire. Just lotsa luck getting it into your state without visiting the state penn. though. Wanna shoot a 50 cal? You can. Wanna use a flame thrower? You can. Wanna shoot an AK-47? You can. Wanna shoot a AK-74? I did, but didn’t like it. It was the most uncomfortable gun I ever shot. I pity the Russian who has to live with that gun. My favorites were the Thompsons.

    If you have not shot a machine gun I think you should do so then decide if there is no recreational value in it. It’s expensive as hell but, in my opinion, it is a lot of fun. Maybe you meant ‘no practical value other than recreational value’?


  12. Herb, where is the 97 now? Do you still have it?

    I did do a write-up including some detail about the innards, but I neglected to take pictures. If it could make its way back to me I’ll take photo’s and make another guest blog about it. It might make a nice compliment to yours.

    Wayne, I do appreciate your comments but I still think you’re giving me a little too much credit…

  13. Herb,

    Thanks for the report. I have been curious about the Tech Force 97 since reading B.B.’s review on the Compasseco site. Naturally, the price range appealed…. And good job Vince. Herb, I agree about the fixed barrel geometry. But judging from the pictures, it looks like cocking a sidelever both standing and from a bench is easier than an underlever.

    I think I will mildly disagree with the saying about you get what you pay for. It’s a fair generalization and probably correct from a statistical point of view, but not absolutely. The Holy Grail of the cheap, high-quality gun does exist. I hate to be boring. Or perhaps I am like Einstein…. It’s said that much of the productive work of his later life was lost because he was entranced with the concepts of General Relativity that he had discovered. In my case, I’m entranced by the value of my cheap guns. The IZH 61 is a super rifle and at less than $100 when I got it, is unbeatable against springers at short range. An even bigger success, though, is the Crosman 1077. For about $65, this has given huge enjoyment for pennies per day for the last year or so. If any of my better rifles is not in top form, the 1077 will equal their accuracy. You can also use it to fight with MacArthur in New Guinea, slamming those clips into the rifle, or you can be part of the FBI HRT snapping the rifle up and zipping multiple targets in quick bursts. In firearms, I would say the Savage 10FP fits the bill. I got mine for $539 and a competent shooter would consistently go sub-half minute of angle with this rifle. To complement the standard AccuTrigger, the AccuStock that is supposed to be coming out promises much for accuracy. (Wayne, get a Savage rifle.) And the Leapers scopes are in the same category. The Leapers 6-24X50 scope that I got for less than $100 has participated in half minute groups with the Savage rifle and will hold zero exactly after being remounted. The fun of playing with cheap guns would be much less if you didn’t know that the dream exists.

    Chuck, what organization is sponsoring the machine gun shoot? Why didn’t you like the AK-47? I’m dying to know. I would have expected the recoil to be much less than a Thompson with its .45 caliber. By the way, I continue to be impressed with Russian technological expertise in all fields. I’ve just learned that their line of Sukhoi aerobatic planes which I’m coming to know of in the rc world are first-rate. In guns and airplanes, the Russians have it figured.

    Also, a word of caution on machine gun shoots. As the saying goes, it’s not the guns you have to worry about so much as the people using them. Awhile ago, there was a story about a kid who was killed at such a machine gun shoot. The kid was 10 years old and was not being supervised by a parent for some reason. He was being assisted by a worker who was 15 years old, and this person made the assumption that a lighter machine gun would be easier to shoot for a smaller person. So, he gave him an Uzi which went out-of-control and shot the shooter. They’re lucky someone else was not killed. That’s why I say that you should be careful of the organization and have a good look at the arrangements. Sounds like it could be fun, though.


  14. Matt61,
    In my comment I called it Knob Hill but it’s really Knob Creek. Here is their web site:


    A link to a copy of the schedule is located here also.

    It is a very well organized affair and has many shooting competitions taking place as well as the machine guns events. It draws a huge crowd so be prepared for that and arrive early and pray it doesn’t rain. If you go please take shooting glasses and a good set of ear protection. You will be wearing ear protection most of the time you’re there. I’m not kidding.

    I was very surprised when I read about that unfortunate incident in my local newspaper. The Knob Creek shoot is much better organized than that. I’m sure the incident will have an impact on how Knob Creek handles things this year.

    I didn’t like the AK-74, which is the newer version of the AK-47. I did not shoot the AK-47 because I had already spent too much money on other guns, but I will shoot it this April.

    The AK-74 had such a narrow plastic like stock that it dug into my shoulder too much. It needs a wider butt to spread out the effects of the recoil.

    I watched a friend shoot the AK-47 and it looked like it had a lot of recoil, and he is a big guy. I was afraid to attempt it. I’m anxious to try it myself now.


  15. Herb:

    You can disagree with me, but you can’t change the laws of physics.

    “In a firearm there is not only pressure but heat. Sound travels faster in hot gas than at room temperature. That also means that the gas molecules are bouncing around faster in a hot gas than a cold one.” All true, but of no bearing to the debate.

    Here’s the problem. If your logic incoporates the speed of sound anywhere, you can be sure you’ve got it wrong.

    The speed of sound has nothing to do with it. ANYTHING can travel faster than the speed of sound, at ANY temperature.

    Heat DOES increase gas pressure, but does in no way enable faster speed limits of air molecules. Adding heat is one of many ways to create an expanding mass of gas.

    Firearms, (like car engines, and rocket motors), create their “mass of gas” through a chemical reaction. Heat is a byproduct that adds a little to the effect, but is, in fact, most troublesome, (particularly in rocket motors).

    Current springers go faster because they create larger masses of expanding gas. A PCP can easily be tuned to do as well, (with no current market value – so we don’t see them)

    Good engineers learn the pitfalls of things that “seem right”. For years they thought the earth was flat, heavy things fall faster than light ones, and it takes a stronger wall to hold back a lake than it does a swimming pool. All “seem right”, all are dead wrong.

    “I’m sure that BB will believe you and not me, so I’d ask that you rethink this”.

    Trust me. Moving projectiles with expanding gasses is so close to what my employer and I do every day, that if I have it wrong, we’ve all got big problems.

    With love…

    Jane Hansen

  16. Yes the Benjamin Discovery is worth it. It is the least expensive PCP on the market, yet it has the accuracy and power of a European PCP.

    You don’t have to pump at all if you use a scuba tank or run the gun on CO2.

    Yes, it is worth it.


  17. Jane,

    Thanks for your remarks!

    << I'm >> rethinking this…

    I appreciate you helping me learn something here. Nice to have someone point me in the right direction!


  18. Herb,

    Nice writeup! I’ve been so busy today I just now got a chance to scan it. I’ll have to give it a good read this weekend after my family gets over this throwup virus going around.

    .22 multi-shot

  19. Worth it,

    I have to agree with BB. Yes, the Discovery is worth it. It is less than $400 WITH the pump! Normal PCPs start around $400 WITHOUT the pump! Pumping the Discovery isn’t that difficult either since it only needs 2000 PSI.

    .22 multi-shot

  20. Chuck:

    1. I just left KY after 30 years there, and I don’t want to start antagonizing anyone, but I’m happy to be gone from the historic gun culture there, where a heckuva lot of people carry concealed weapons and believe it is their God-given right to shoot anyone who irritates them. I’m now back in the Midwest, where most folks (I emphasize MOST) like guns for hunting or other forms of sheer sport. I hope yu’ll enjoy the Knob Creek shoot, but I’ll take an afternoon at the local country sportsman’s association ranges.

    I’m all for personal protection and gun recreation, but if you are honest with yourself, you may have to consider that owning and firing AK-47s is not a very practical form of recreation, unless you have your own 100-yard gun range and unlimited money for ammo.

    On the other hand, I think the AR-15 lovers are completely rational about liking the civilian semi-auto version of an interesting and flexible (albeit expensive) firearm.

    But, what can you realistically do with a fully-automatic weapon that is a week-to-week form of entertainment?

    I may be missing something, but the biggest draw of fully automatic “assualt” rifles is to outgun the opposition. In the hands of the police or the military this is wonderful. In the hands of bad guys, this is disaster.

    (I do not think I’m going to convince anyone of my position, but I hope you can at least see my point of thinking the balance is too far in favor of bad things happening when any crazy guy or criminal can shoot streams of armor-piercing rounds.)

    2. On a more peaceful and collegial note: I have a relatively cheap Tasco Pro Point on my Daisy 953. I couldn’t see paying more for the red-dot optic than for the airgun, so I passed on the $100 and up brands. I confess I got the Tasco at WalMart. It has both red and green recticles, and holds a small dot without turning into a useless blob, which is the trouble I had with my first cheap red-dots (ie: Crosman’s basic reflex red-dot sight). Both red and green dots have 6 brightness settings, and the green reticle works great outdoors on a sunny day.

    My eyesight is poor, and despite B.B.’s advocacy of open sights, they don’t work for me. I can’t see the front sight at all, unless I’m using a peep sight (which changes the optics of the eye’s vision), and then the target has to be pretty close.

    The red-dot technology allows me to shoot in situations when scopes are not the answer, such as my basement range or ranges of 25 yards or closer.

    3. THANKS B.B. for the explanation on sighting in a red-dot. I thought that must be the case. I’ll reivew all your many great previous explanations about how to sight in and get the best from an optic on an airgun.


  21. Matt,

    RE: “But judging from the pictures, it looks like cocking a sidelever both standing and from a bench is easier than an underlever…”

    I didn’t find the TF97 awkward to cock at all. It was awkward to get the gun in a position where you could see my left hand blocking the cocking arm and my right thumb in the breech.

    I understand why models would enjoy a massage after a photo shoot! I don’t have a studio setup and found it quite involved to get the right pictures. I probably spent more time on the pictures than I did writing.

    All in all doing the guest blog was a blast. It really does make you appreciate even more how much effort BB and Edith put into this project. Group hug for them!


  22. Leon,
    Thanks for the info on the red-dot. I think I’m going to give it a try. My eyesight sounds about like yours.

    I like the local sportsman’s gun range, too, but it’s interesting to hear your comment about simi-auto Ar-15s vs the auto AK-47s. I think if I were to go face to face with two guys, one with auto and one with semi-auto, I think I’d chance the auto guy. The auto guy, unless he is really trained is going to be much less accurate than the semi-auto guy and use his ammo up much faster. However, I will concede that my standoff with the auto guy may cause more collateral damage and innocent bystanders to duck for cover.

    Your comment about CCW gun toters in Ky is interesting because while there may be a bit more bravado coming from CCWers, I don’t hear much here in Illinois about rampant accidental or intentional killings in Ky from CCW people. The Ky tourist bureau must do a good job of covering that up. However, I do hear a lot about thugs here in Illinois victimizing helpless citizens. I’d still vote for CCW.


  23. I intend to get a tin of Crosman Premiers and a tin of JSB Exacts to try in my rifle- JP

    I use both of them in both .177 and .22 in most accuracy tests because one or the other is usually on top of all other pellets. -B.B.

    Hi B.B.,

    Could you be more specific about which of the two brands you use (I notice for instance, that there are HEAVY Exacts as well as lighter ones, etc.)? I'd like to add some of both brands (in both .177 & .22) to my next PA order.


  24. Matt,
    My IZH-61 is a side lever and my Daisy 953 is an underlever. I find the 61 side lever very much easier to use. My Ruger AirHawk is a break barrel and it is the hardest to use. My Walther 94 is CO2 and it is soooooooo much easier to use. Some day I’ll get a PCP so I can compare that, too. Is there a Discovery in my future – maybe if a $100 more can’t beat it.


  25. B.B. and Chuck, yes I’ve heard of the Russian small caliber cartridge. I thought it was 5.45 but same idea. One of the few compelling bits of evidence I see left for the 5.56 type as a lethal round is that the Russians gave up their perfectly effective 7.62 for it. But perhaps the move from .45 caliber to 9mm is another case of being misguided on a large scale. So maybe the Russians are fallible after all. Odd too that the AK74 caused recoil problems. Low recoil is supposed to be one of the selling points of the small round.

    Chuck, tell us how the AK47 feels. There can’t be that many hear who have experienced it.

    Herb, I give you a lot of credit for the photos. I know what a pain that is.


  26. Leon, I have not now nor have I ever been a Kentuckian. But I just looked it up and it appears that between 1998 and 2007 the murder rate in KY has been below the national average except for one year, when it was 2/10ths of a percent above.

    Idaho had a very low rate. Maybe it’s because potato guns aren’t as lethal? 🙂

  27. Matt,

    You’re right about the caliber being 5.45mm. I just said 5.56 because I don’t keep it stored in my memory. I trip over the cases at my gun club all the time and wonder what the shooters think of them.

    I shoot a semiautomatic SKS that fires the 7.62X39mm round and I can tell you that it is a dream come true. The round has very little recoil in a semiautomatic action, yet it delivers power in the .30/30 range.

    I have an early Russian SKS that is a tackdriver, as in half-inch groups at 50 yards. Until getting this one my only experience has been with several Chinese SKSs that grouped 2-3 inches at 50 yards.

    I have also fired a semiauto AK and the recoil seemed to be even lighter than the SKS. It is a wonderful battle weapon and like you I wonder why the Russians decided to go with the smaller caliber. I know all the popular arguments, but if they are used for an ineffective round, they make no sense. So I guess the Russians bought into our lie on that one. Maybe that is a final cold-war slap!


  28. Joe B.,

    First of all, Kevin was right. I don’t use Premiers from a tin. I buy them in the box.

    Second, I use ALL weights. For springers I use the lighter weight and for gas guns and PCPs I use the heavier weight. That applies to ALL calibers of ALL pellets.


  29. Vince, Chuck, et al.:

    You guys are correct that KY does not have a high rate of murder or accidental shootings. What drove me nuts was the attitude that killing was OK if your honor was impugned–it was, as you say, mostly bravado but it got me downr after three decades there.

    If I lived in some parts of Illinois (Chicago), I’d have a scattergun at my bedside and a concealed-carry weapon with me at all times.

    I also was not thinking of the AR-15s as a weapon but as a recreational firearm. When I first came to realize there are lots and lots of AR-15 owners, I was confused, thinking they were all eager to start gun fights. Then, I figured out they are probably, at the core, mostly people who like the versatility of the black guns, and they don’t really intend to fight it out with bad guys who have assault weapons.

    If I had to do so, I’m with you…I rather have superior firepower. But, I usually shoot rimfire guns or airguns, so I’d better not get in a fire fight!

    Thanks for your courtesy and thoughtfulness in discussing this. I’m closing my comments on the issue.

    Chuck: Good luck with the red dot. I think they are God’s gift to old shooters or anyone with bifocals. I forgot to say that my Tasco cost around $45 and seems to be a winner. You can pay a lot more. The Tasco mounts on a Weaver rail, which calls for some kind of conversion for airguns with 3/8″ dovetails. That’s not too hard to do.

    I also got a no-name, made-in-China red dot for $25 from a farm supply store (we have a lot of those in Iowa). It must have been manufactured by some OEM company, because it looks and feels like a BSA sight. I don’t know if it will last, but it performs well at close airgun range and mounts in a few seconds on a 3/8″ dovetail.


  30. Leon,
    The citizens of the Bluegrass state are happy that you are back where you feel safe. Did you really interact with people here or treat them according to something you obviously read or saw on a PBS documentary?

  31. I might add that my very favorite machine gun, although I could never shoot one effectively, is the British Sterling 9mm. I’m glad I never had to fight with it, although, maybe I would have developed right brain synapses over time.

    This gun was a joy for me to shoot for some reason. The recoil was moderate and exhilarating. I could have shot it all day.

    The reason I wouldn’t be effective is because the rather long magazine clips into the left side of the gun and becomes the handhold. I am left handed therefore the gun feels awkward to me because I want my left hand on the trigger and my right hand on the magazine. I had to shoot it the opposite way I naturally shoot.

    I tried to use my left hand on the trigger and reach over the top with my right to grasp the magazine but you can imagine how comical that must look, plus it was impossible for me to get a good grip and really impossible for me to use the sights.

    Maybe someday left handedness will get my people exempted from military service. Har, har!


  32. Happy Weekend to One and All,

    Can someone please give me some help/advice on rebuilding a Discovery Pump. More speciffically how do I remove the solid rod that connects to the handle. I am thinking that there must be a seal or something connected to it that is “out of wack”.

    I’ve got it torn down, except for the rod assembly, and everything seems to look ok, but I really don’t know what I’m looking for except for bad o-rings. Rather than assume that it is, is silicone the grease I should use, and last but not least what durometer rating for the o-rings? Thank you so very much.


  33. Jane,

    Ok, finally figured out where I really fouled up. I should have asked you to collaborate, not try to go head-to-head with you.

    I really think because of your experience you are missing the factor with which I am struggling. As I understand it, a rocket is designed to get thrust, in other words, momentum from the compressed gas. You do that by maximizing the velocity of the gas molecules leaving the rocket. Not sure what you call it, but the molecules are quickly too far away from the rocket to have any effect on the "new" gas molecules coming out of the rocket.

    Let's overlay rocket technology on an air rifle. Assume a "transfer port" could be designed so that it was a perfect DeLaval nozzle. Now in order to get higher gas velocities, you just increase the pressure of gas. You pump the pressure in the gas reservoir form 2000, to 3000, to 4000 psi, and so on ad infinitum. Pellet velocity is thus unlimited.

    BB has always said that to get more velocity with a PCP you just need a longer barrel. So let's use the maximum length barrel. Don't know how long that would be but what happens at the end of the long barrel?

    Well in order to get the maximum velocity for the rifle the barrel has to be so long that gas pressure at the tip of the barrel drops to atmospheric pressure.

    Now as the starting pressure of the gun goes up, I need to use a longer barrel for a higher pressure. But ultimately atmospheric pressure is what it is.

    Neglecting friction, assuming a massless pellet, and all sorts of real world problems, Seigel showed that the maximum velocity at the point of the barrel where the pressure dropped to atmospheric pressure was 5 times the speed of sound for the compressed gas. Right?

    Seigel, Arnold E., "The Theory of High Speed Guns" which is available here:

    equation 11-8, page 19 of text, page 34 of pdf file

    Now the question is – "Does the ultimate limit, as noted by Siegel, really impose any practical limit on an airgun with a finite barrel length and firing a pellet with a given mass?"


  34. Joining a discussion on the maximum velocity of a pellet here is like starting a thread on which is the best oil to use in a motorcycle on a bike forum but at the risk of creating a monster, let me throw in a query. Today, while at the local bike shop, I got to talking with a pretty knowledgeable engine tuner. He used to do two-stroke competition bikes for Bonneville Speed week. He made a comment that one issue he always had to be leery of was the intake airflow going supersonic. The shockwave that would result would disrupt his intake charging.

    While Jane is dealing with either solid fuel or non-compressible fluids (nasty stuff that’s highly toxic) unless you’re doing research more on the NASA side, I don’t think you worry about a negative shockwave in the feedstock pipe. Jane, I also offer my apologies for having you think of work on your time off. Herb, CJr. and BG, with all the discussions and formulations you guys were having great fun throwing about, did that ever come up? That is, the airflow through the transfer port and down the barrel reaching supersonic speeds and setting up a negative shockwave that would retard the wave front?

  35. Fred,
    Personally, I don’t think synthetic is any better for your bike than regular oil.

    I think synthetic makes your bike clatter (annoyingly) more with some reduction in heat but not enough to justify the price difference. Regular oil is cheaper. Plus if I get out on the desert on a Sunday and need a quart of oil I can get a temporary replacement at a truck stop.

    I’ve been running regular oil in a 2003 Harley Heritage Classic for 65,000 miles with no problems.


  36. B.B.

    I should have figured that you have experience with these Russian assault weapons. So, perhaps this is an answer to my query of long ago about the SKS vs. the AK47. MOA from an assault rifle is very impressive. Do you recall if the accuracy of the AK47 was as bad as people say?

    All, a propos of our conversation about machine guns and lethality, I have just become aware of a weapon called the AA12 automatic shotgun. I had heard about this technology and understood that the various models were basically novelties. But the design has been revised into something new. The weapon fires 300 rounds per minute of 12 gauge shells. Various projectiles can be loaded–both the slug and shot variants–as well as a mini-grenade with stabilizing fins that reaches out to 175 yards. In addition, the gun claims to have achieved several holy grails of gun technology, namely almost non-existent recoil and zero maintenance. Vince, I’d say you have a bit of competition.

    The only explanation I can get for the slight recoil is something called “constant recoil” which has to do with a two stage spring, whatever that is, that does not allow the bolt to come into contact with the receiver. Anyone know anything about this? As for the zero maintenance, that is supposed to be due to stainless steel construction and loose tolerances. Again, nothing really profound that I can see.

    Videos abound on YouTube, and one site claims that this is the ultimate weapon for laying out zombies, and I would say they are probably right.

    Initial military tests have been passed with flying colors, but it remains to be seen if our generally clueless military acquisition system will go ahead with this. I will be watching with interest but not much hope.

    Therein lies an interesting subplot. The designer of this weapon is a fellow named Jerry Baber who apparently has some notoriety in the gunsmithing field. He has encountered some static from military acquisitions. So, in response, he is trying to mate his shotguns with robots, both on the ground and a helicopter. It’s like Robocop. Remote control meets firearms!


  37. Herb And Jane,
    It appears as though this topic of maximum speeds has been researched quite extensively by scientists, engineers and physicists. The results of this research Is readily available on line in dozens of places as Herb has mentioned several times.
    Apparently the formula for calculating this speed has a great deal to do with the speed of sound in the propellant medium.(in this case,air)
    This speed would be limited to approximately 1640 feet per second for a precharged pneumatic rifle using compressed air as a driving medium, regardless of how high the pressure was.
    The speed could be greater in a spring-piston gun due to the extreme increase in temperature caused by the rapid compression of the air.
    There is a quick and concise explanation of most of this at “Nation Master-Encyclopedia:Light gas gun” (As well as the more in depth sites that Herb has already mentioned. Love, Jon F.

  38. Fred,

    RE: March 07, 2009 7:29
    “That is, the airflow through the transfer port and down the barrel reaching supersonic speeds and setting up a negative shockwave that would retard the wave front?”

    Jane was chumming the sharks here asking almost that very question a while back. Since she IS a rocket scientist, she wanted to know if a rocket scientist familiar with nozzle design had tried to tweak the design of transfer port on a springer. Better design yields better flow.

    I certainly don’t understand the whole rocket thing, but I have gotten familiar enough to throw around some buzz words. Basically as I understand it there are more or less two situations. With unrestricted flow you can have an “unlimited” flow of gas. For a choked flow there is some constriction at which the gas flows through at sonic speed (speed of sound). The mass flow of the flow at steady state is a constant. So flow goes faster in some parts than others.

    Once the airflow leaves the area adjacent to the transfer port another set of problems creep up. Since the gas is compressible, it creates zones of compression. This does in fact retard the flow of gas.

    All in all the gas flow is a very dynamic and very complex situation to model. It is made worse by the fact that a steady state is never really reached. It isn’t like you are trying to blow gas from a high pressure area to a low pressure one for a very long time. I’d guess that the typical PCP valve shuts before the pellet exits the barrel to conserve compressed air. Because there are various choke points when the gas flow is stopped it doesn’t totally stop the acceleration of the pellet.

    Hope this helps..

  39. Jon F.

    Re: “This speed would be limited to approximately 1640 feet per second for a precharged pneumatic rifle using compressed air as a driving medium, regardless of how high the pressure was.”

    Just was digging thorough this on the yellow forum. Don’t want to keep posting links all over place so see Tuesday blog on how fast can a pellet go to find link.

    The gist is that the Yellow Formula does not actually predict an absolute limit from first principles. It starts off with work and then tweaks the equation with the interjection of an empirical term into the equation. I recalculated equation and the “limit” drops quite a bit. But it is still a result which seems in the right ballpark and tantalizing. Could it be fixed with some more tweaking?

    See comment above that I made to Jane for another source. In this case 5*(speed of sound) does seem to be an absolute limit. a 5,600 fps air gun would be interesting to say the least.


  40. Matt,

    The AKs I have shot were not accurate guns. Their claim to fame is firepower and reliability. As much as it hurts to admit it, an AK is quite a bit more dependable than a Garand. But they will never shoot like one.


  41. “Videos abound on YouTube, and one site claims that this is the ultimate weapon for laying out zombies”

    Hi Matt,

    I’m not so sure about that. Think about it…according to the 3 current popular movie-series-based-on-a-video-game, you have to shoot them in the head so they stay down. Since they have rotting heads anyway, and a shotgun slug is so powerful at minute-of-rotting-zombie-head range, you’d be using an over-penetrating round.

    Now that’s just asking for a lawsuit, that is.

  42. Herb:

    I glad to see that you’ve discovered a new fascination with interior ballistics.

    Siegel’s compendium was often quoted a few years back when certain Middle-east countries were dicovered importing huge sections of reinforced pipe, and the fear was they were constructing the barrel of a huge “Supergun” that could hit targets hundreds of miles away.

    Of course, Siegel’s work goes back to 1965, but even then there were guns that sent projectiles at 40,000fps.

    What is very interesting is the work on “Chambered, Preburned-propellant” interior ballistsics.
    This is, in effect, a PCP rifle.

    The first think to recall is that the equations worked mightily to predict the rarification of that “mass of gasses” as it worked down the barrel, and at what point the barrel length may cease to be of benefit, (a very key point if you are wondering if the stack of pipe in a neighboring country is for oil pipelines or missile launchers). We no longer believe that the gas “rarifies” by the stratification theories postulated during WWII. Secondly, Siegel will mention several times, that these are “high-speed” effects – greater than 10,000FPS. I don’t really see us getting there.

    From a practical perspective, I think we can all agree on several points:
    1. The difference between PCP and CO2 is primarily one of pressure, (CO2 is consistent, but substantially less).
    2. We’ve seen in some of B.B. experiments, and Crossman’s comments, that CO2 barrel lengths are pretty-much optimized. That is, making them too much longer enters the point where friction overcomes any remaining pressure-induced acceleration.
    3. PCP barrel lengths aren’t too much behind. Without doing too much calculation, we’re still a foot or two from optimum for valve release pressures in the 1500psi range.
    4. We’ve got several guns that exceed 1200fps, (well above that “speed of sound”).

    So, somewhere between Herb’s estimation of about 6000fps, Siegel’s prediction of 80,000fps, (here with hot, light, propellant gas), and the 1200 we see routinely, we have some (?) idea of where we’re going.

    My prediction fo what we’ll see in the next few years:
    1. Longer barrels, on the order of 2-3 inches, as we get used to the 46inch “look”.
    2. Larger air reservoirs, either by the trend towards rear air bottles, Gladiator-style “dual air”, or larger tubes under longer barrels.
    3. Higher pressures.
    There are EU offerings already at 220 bar. For sure, they’ll go higher.
    4. Higher-capacity valving and porting. We can easily release more air, at much higher pressure, over a longer period of time, to create more pressure, and optimize longer barrels.

    It won’t take much to get a PCP in the 2000FPS range.

    I can’t dissuade you enough to stop worrying about the speed of sound. Firstly, because we’ve already passed it, (and remember, Siegle was referencing work of mathematicians who still believed in a “sound barrier”). Secondly, because, even as we choose to use this as a mathematical parameter, it is not constant, and even Siegel saw that the speed of sound behind the projectile was much higher than ambient, (due to higher densities).

    best regards,


  43. Jane,

    Fascinating comments! Thanks.

    I’m not “worried” about the speed of sound just using it as a stake. As a chemist I am familiar with the Maxwell-Boltzmann distribution and the most probable velocity, the average velocity and the RMS velocity of gas molecules. I certainly don’t see it as the sound BARRIER.

    I think this really all goes back to your earlier question which was basically – Has a rocket scientist optimized design of airgun for the best performance? I think we can all agree that the answer is NO.

    After having fooled around with a lot of calculations, I’m getting convinced that there is still plenty of room for improvement at room temperature. We don’t have to heat the gas to make the molecules move faster to get more power to the pellet.

    Thanks again!

  44. See what I did?

    And to CJr., I refuse to take the bait 🙂 other than to say when I used synthetic in my 1984 FXRT, it leaked out the cases, the air cleaner and every darn gasket face on that evolution engine. It was too thin. Remember that Harley is one of a few that has a separate oil supply for the gearbox – all the Japanese and English bikes use the same oil reservoir (and Italian) and, ah, you got me. That’s it. Good day today to go shooting and ride one of my bikes – with it’s synthetic oil!

    Remember to set your clocks ahead!

  45. RE: Siegel's work & helium

    Guess the other thing that I found fascinating was using helium as the pressure gas. Being lighter than air, helium molecules would move faster. Hence helium should blow out of the barrel faster than air. Overall though, it doesn't seem that the slowness of the molecules causes any real problem.

    It would be really fascinating to have velocity numbers for air and helium at the same pressure. That would give us some idea how close to molecular velocity limits we are. If helium is just a few percent faster, then speed of air molecules isn't a real problem. If helium is twice as fast, then the speed of air molecules is a significant factor.

    But if someone wants to/can try this – DO NOT decided to do even better. Hydrogen weighs even less than helium. But hydrogen and oxygen (from air) are a nasty mix. Goofing around with hydrogen could be really problematic. So I'd suggest that under no circumstances should hydrogen be but into a PCP.

    Helium wouldn't be any more of a safety problem than pure nitrogen. It would displace oxygen, put asphyxiation is a unlikely problem. The gas pressure is the real safety issue.


  46. To BG Farmer: I guess I thanked the commenters on this blog for their courtesy too soon.

    To Matt61:
    OK…this will probably call for more derision from guys like BG Farmer, but there is a terrific article on Jerry Baber and the AA-12 in the Feb. 23 editon of the NEW YORKER. After you read that and look at the videos on You Tube, you want to scream that the military has not adopted it instantly. What a weapon it would be in “urban” warfare.

    To Chuck:
    For a good discussion of red-dot sights, look at http://www.ultimak.com/UnderstandingE-Sights.htm

  47. Anonymous Zombie,
    You are very correct. You must hit the zombie in the brain. It is the only way to kill them. That is where the virus exists. Even if you chop the head off the head still lives and can bite you and turn you into a zombie.

    The shotgun you mentioned is impractical for zombie hunting because you will waste too much ammo on one zombie. Remember you have to carry all that ammo and I can’t imagine carrying around 100-200 rounds of shotgun shells. The ideal weapon is a scoped semi-automatic rifle. It’s lighter and so is the ammo. Keep that in mind when the infestation happens. And carry a pistol for those close encounters. A machete would be nice too, but now you’re getting too close.

    “And to CJr., I refuse to take the bait :)”

    Well, OK, but you started it! 🙂 However, it’s reassuring to know there are responsible bikers like you out there.

    Anonymous Zombie, Matt, and Fred,
    Thanks for giving me a chance at attempting to set the record for being totally off topic.


  48. Jane & Herb,

    Boy, am I glad to hear we have faster air guns to look forward to:)

    "not to worry over the speed of sound"???

    Do we think we can solve the problem of tumbling pellets? And have accuracy/high ft. lbs. and speed?

    Isn't that the question… what good is the speed, without the accuracy..

    Unless this is just a dance between smart people… in which case, you two dance very nicely together!! Thanks for the show!!

    Wacky Wayne

  49. Jane,

    If I could ask for your expert opinion again?

    Would the difference between air and helium as the fill gas for a PCP be indicative of getting to an absolute limit, or more just that there is a flow problem?

    Thinking about this at lunch I realized that helium would just flow significantly differently than air. It would seem that testing PCP with air and helium might be a good way to tweak design to improve flow problems. The ratio of helium to air would likely change more than the absolute difference in pellet velocity measured with air.


  50. Anonymous red-dot/ultimax site,

    Thanks for directing me to the red-dot site. It was very good reading. When I clicked on one of their sight links I about choked on my coffee at the $800 price tag. Dang, those (little) things can be expensive. Ah well, when it comes to hobbies and sports money is no object, eh?


  51. Chuck,

    Remember B.B. promised us an article on the new leapers green laser’s he saw at the shotshow. Maybe this should be a consideration since you’re gathering info on the red dots.


  52. Wayne,

    RE: “Do we think we can solve the problem of tumbling pellets? And have accuracy/high ft. lbs. and speed?”

    Every mangle a pellet on purpose? I was playing around and cut the skirts, and also filed a flat spot on head of some round nose pellets. They still shoot pretty well even after significant deliberate damage!

    I like the diabolo pellet. I’m shooting inside a city and I don’t want “pellets,” aka bullets, going a mile.

    If we had a pellet going over the speed of sound (sorry Jane for my fascination again…) then the ballistic coefficient for the projectile above the speed of sound is likely to be very different than it is below the speed of sound. Think you’d have to switch to more of a bullet design to keep the velocity of the projectile from decreasing too fast. Even if you could quiet the muzzle discharge, there is nothing that you can do about the sonic boom of the projectile as it breaks the speed of sound. So quiet and discrete shooting is out of consideration.

    Back to the accuracy issue. Something that really intrigues me is the notion of the pellet spinning versus it spinning and precessing. With precession it would seem that the pellet would curve more. Also with precession the ballistic coefficient would be lower. I’ve been wondering if you could use the sound of the pellet to determine if it is precessing and at what rate. Trying to get motion pictures of the actual pellet flight requires equipment beyond my financial reach.


  53. Chuck,

    You’re very welcome.

    And remember, if the movies have taught us anything, it’s this. Never walk backwards in a building filled with zombies without looking over your shoulder; they’ll get you every time. No matter what weapon you’re using.

  54. Anonymous Zombie,

    Hey, did I just give you a new handle?. Or you could be one of Rob Zombie’s (musician, film director, screenwriter and film producer) illegitimate kids. Also, sounds like a good name for a rock band but too much like “White Zombie”, which has been done.

    BTW, if you’re a PC gamer you might want to try Left4Dead. Also, there is a good book by Max Brooks called “The Zombie Survival Guide” (my brother gave it to me for Christmas). It’s a tutorial on how to survive a Zombie infestation.

    Sounds silly, I know. But, it has well thought out tips and techniques that would be useful for preparing for and surviving any post “Apocalyptic” future. If there are any Survivalists out there (which I’m not) this would be a must read.

    Thanks for the heads up on the Leapers green laser. I had my red-dot finger poised on the Pyramydair submit button. I retracted just in time. Maybe I can get both and save shipping and handling.

    If I wanted to author a post on red-dots, lasers, and holographic sights (however, I’m sure BBs already done it) it would be a one-liner pointing to that web site (and BB’s). It pretty much says it all.

    Green laser? Hint hint!


  55. Leon?Anonymous?

    I’m sorry if my mostly tongue-in-cheek comment offended you, but you must admit you painted us’uns with a pretty broad brush:). Inasmuch as your view is by necessity subjective, I can’t dispute it, but it does differ markedly from my experiences.

  56. Herb / Wayne:

    You raise some interesting ideas. Just a few thoughts…

    First – “spin stabilization”. We spin a projectile keep it’s nose facing the wind. A gyroscopic response then corrects any deviation in pitch or yaw. Precession is the side effect of spin stabilization, as the projectile will move in response to the layer of spinning air around it.

    (With a good scope, and the right outdoor lighting, you can actually see a pellet in precession over about 40 yards)

    The phenomena are the same at any speed, but of course varies with speed; so every pellet design has an optimum speed and rotation – what must change is the rifling rate as we change the velocities – yet another reason why each gun has a “sweet spot” and “sweet pellet”. A fast pellet will have a slightly different design than a slow pellet, to be ideal.

    Lucky for us, this no no big deal, even at supersonic speeds. The popularity of such new ammunition such as the new .177 rimfires, (2000fps), or the 30-06 Express (4000!fps), is supersonic delivery right to the target.

    We have no problem with turbulence, shock wave, or sonic booms, because the projectile obtains supersonic speeds before the muzzle. Any ill effects of breaking ahead of our own waveform is behind us, and won’t present any problem until we drop down through this “barrier” as we slow down.

    A 2000fps projectile delivers a nice, flat, (about 4inch), trajectory for at least 100 yards, making hunting anything within that range a breeze.

    As we think about helium, let me suggest a thought experiment.
    Imagine traversing the Atlantic in the (now defunct), SST. Take-off at 200mph, and gradually passing through the sound barrier. Curiously, (or not), we feel absolutley no ill effect – even though every air molecule, our martini glass, and our own intestines have essentially broken the sound barrier and continues at supersonic speed.

    The plane has to deal with some turbulent air molecules as it is buffeted by its own soundwaves, but even that is for a brief moment.

    The point, of course, is that this is simply no restriction. Helium’s advantage is, back to Siegel’s equations, the ability of the helium itself to accelerate faster in reponse to the force applied – the theory is that the rarification /stratification effect behind the pellet should be less, and hence, we should gain more acceleration for a given starting pressure.

    I for one, wouldn’t consider it.
    1. It’s rather impractical.
    2. Any change is likley to be imperceptible – these effects mostly seen at extremely high velocities.
    3. It would be expensive.

    Lot’s of other things to experiment with…


  57. Hey guys!
    I discovered that the Crosman 2100
    looks like the Remington nylon 66!
    I read a article on the nylon 66 in
    American rifleman, and it had a
    picture of it, And low and behold,
    it looks like a 2100! is it perhaps a replica? wondering if you guys knew or not.

  58. B.B.

    Thanks for confirming my impressions of the AK47. I had heard that much of the AK47 design, at least the gas piston part was copied from the Garand, so I thought that the reliability might be comparable since much of that seems to depend on the piston. If the extra reliability of the AK47 comes from its extra loose tolerances, I feel better since that seems like something of a devil’s bargain that impairs accuracy for reliability. It seems analogous to me of the way the M-16 trades reliability for accuracy by dispensing with a piston in order to have fewer moving parts. It seems that one wants the optimum balance of reliability, accuracy, and lethality and, as you pointed out, the Garand is still it!

    I’m waiting for a new book titled something like Infantry Weapons in WWII made up of oral histories of American soldiers using their personal weapons. The excerpts are loud in their praise of the Garand’s reliability with some descriptions of how it worked after being dragged through mud which is what you hear of the AK47. Also, in my History of the American rifle book, it says that the Garand was noticeably inferior to the Springfield 03 in reliability tests by the U.S. Marines involving hosing with water and dragging through sand. However, the rifle performed much better than indicated in actual combat with about equivalent reliability, so I guess that definitive data is hard to come by.

    Regarding zombies, thanks for the New Yorker reference to the shotgun which I have heard summarized. I’m tracking it down. Most of the web stuff seems to correlate it. Also, I believe that zombies have evolved past what you are describing. Have a look at Will Smith’s I Am Legend. One shot shows the zombies shuffling towards his SUV in the old-fashioned way, then breaking into a sprint like antelopes. They are also capable of hurling themselves onto searchlights in a self-sacrificial way to further the mass attack. They’re not to be messed with.

    I don’t know why you would want a scoped rifle to snipe them with from a distance and attract their attention. Much better to stay out of their way. Besides, there is always the fin-stabilized mini-grenade to reach out to 175 yards. However, if massed zombies are charging towards your SUV or are massing to overrun your hiding place, you want this shotgun to put out a wall of lead. Slugs or shot hardly matters with this thing.

    As another close-in weapon combining mobility and power, some movie featured a large muscle-car with a flatbed or perhaps a retractable top from which you could wield a sledgehammer.

    I wonder if those in the gas pressure conversation could spare a moment to clarify something for me. Assuming one would want supersonic velocities in the first place, I guess I don’t see how the speed of sound relates to this question since, as Jane mentioned, the barrier has been broken anyway, and I don’t see how this barrier has any physical effect on the projectile, not it’s speed anyway although it does retard accuracy. The only thing I can think of on the other side of the argument is that gas under certain conditions like being “rarified” or heated changes its properties somehow so that its speed of sound is different from regular air and will somehow accelerate a pellet faster as well. Is that right?


  59. RE: Helium

    Certainly wouldn’t recommend it as the “standard” fill, but I still find it curious as to how helium would compare to air.

    Rumors abound that it is “significantly” faster. Everyone that mentions helium in a PCP says that it is faster, but I couldn’t find any hard data to support the claim.

    I agree that to use helium for the long haul would be expensive. But to use it for a few experiments, you wouldn’t need much. The problem is that you’d like to pay for just the helium, without having to buy all the equipment to handle it.

    I never worried about the cost of the helium I used. It just went into the lab budget. 😉

    I think the answer to my question about helium was in Jane’s point #2.

    “2. Any change is likely to be imperceptible – these effects mostly seen at extremely high velocities.”

    But molecular velocity limits aside, it does seem likely that the gas flow in a typical PCP has bottlenecks which would restrict gas flow. Since helium is more “fluid” than air, it just might be detectable faster. If so, the amount would no doubt vary from rifle to rifle. Or it could be that helium being faster in a PCP is another urban legend!

    Anybody seen any REAL data?


  60. Matt,

    RE: “I wonder if those in the gas pressure conversation could spare a moment to clarify something for me…”

    Not sure exactly what you asking, but I’ll try.

    First there is no “sound barrier” per sey. The speed of sound is just a convenient stake in the ground. The transonic region does have implications on accuracy as you pointed out, but that is a different problem.

    RE: “The only thing I can think of on the other side of the argument is that gas under certain conditions like being “rarified” or heated changes its properties somehow so that its speed of sound is different from regular air and will somehow accelerate a pellet faster as well. Is that right?”

    Not really. The kinetic theory of gases says that the kinetic energy of gas molecules depend on their temperature. Since helium atoms (which is a molecule) weigh much less than oxygen or nitrogen molecules, the helium atoms have to move faster to have the same amount of kinetic energy. Sound is a wave motion through the gas and depends on how fast the gas molecules themselves are moving. Since helium atoms move faster than nitrogen/oxygen molecules, the speed of sound in helium is faster than it is in air. About three times faster in fact.

    To illustrate why I am so fascinated with this, imagine an airgun shooting no pellet. The gas is pumped out of the barrel and I have my Start Trek force field blocking the tip of the barrel. Now assume that the first molecule of gas that hits the force field makes a “PING” when it hits the force field. After I fire the gun, it takes a finite amount of time for any gas molecule to make it to the end of the barrel. Finite time here is the key.

    The basic question is “Does the ultimate velocity of the pellet depend on the molecular speed of the molecules in the gas?” In other words, does the final velocity depend on how fast the gas molecules can push themselves (and hence the pellet too) down the barrel?

    This help?

    To explain a bit more, the kinetic energy of the gas molecules does not depend on pressure – at all (well at least in the perfect gas). So gas molecules at 2000 psi are not traveling any faster than gas molecules at room pressure. But here is the rub. Release the high pressure gas into the atmospheric pressure. The high pressure gas does have energy stored. This energy is converted into kinetic energy of the gas molecules. The “static” pressure of the gas is just atmospheric pressure. But there is a dynamic pressure too in that the released gas is flowing away from the orifice. The gas molecules in the flow are thus traveling faster than the average gas molecules in the room.

    Help more?


  61. Matt61,
    Please don’t confuse Hollywood with the real menace of zombies. Doing so will surely get you killed. I, for one, do not want that to happen. Also, if you are fortressed, you are correct. The shotgun will help, but it is too short ranged for fortress defense. Plus, you cannot stay fortressed forever. You will eventually be overrun. You must move out of the infested area and go to Remember, you are interested only in self preservation. You must run either to Wayne’s place or that guy who lives out in the boonies (Ashland is the boonies, also, I say that in the most respectful way. My sister lived there and I loved it.). You only fire a gun at zombies when absolutely necessary for the reason you describe. In which case the semi-auto conserves ammo and gives you some accuracy at range.


  62. Ian (ChosenClay),

    I believe you’re right. The crosman 2100 began rolling off the assembly line in 1983 just when the crosman model 766 production was ending. The 2100 looks alot like the 766 and the 766 was modeled after a Remington autoloader firearm (nylon 66?).

    Good eye!


  63. Groan, blogger just froze on me wiping out the following comment. Has anyone noticed that this has been happening quite a bit?


    Thanks for your explanation. Fundamentally, I was asking what your debate was about. More specifically, I was wondering what the speed of sound of a gas has to do with projectile acceleration, and your answer has made that clear.

    My sense is that gas selection would not have an effect on pellet velocity for the following reason. For energy to be put into a gas through compression and then to produce different projectile velocities seems very odd. It looks like a violation of the principle of conservation of energy. The energy that goes into a system should be the same that comes out. For a gas like helium whose molecules are moving faster, their lighter weight should be such that the energy transferred to the projectile should be the same. Is that right?

    Herb, mobility is key in combating zombies, but now enter another property of this singular weapon. The rate of fire was purposely chosen to be slow enough at 300 rpm that it can be controlled with a little practice to fire three round bursts, double-taps, and even single shots. The finger is the selector switch and ammo can be conserved. Accuracy would not be on a level with a semiauto, however, with the negligible recoil combined with variety of ammo, shot at close range and bursts of slugs further out, I don’t think you are giving up too much to the semiauto. With different magazines loaded with shot, slugs and minigrenades, you’ve got everything covered out to 175 yards which is all the range at which you would engage zombies anyway. This thing is like a much simpler and cheaper version of the OICW combining a computer-controlled grenade launcher and assault rifle which collapsed under the weight of its own technology. Reports are that troopers of the 82nd Airborne testing prototypes were helpless as turtles when lying on their backs.

    I’m all for providing our troops with the best firepower. However, I don’t get the sense that deficiency of firepower is a real problem in the War and Terror, and I do wonder if maybe this weapon was better off not invented. Once the military uses it, undesirables are going to find a way to get hold of it, and God help the civilians, police or soldiers who get in the way. This is the old dilemma of defense: in order to deal with a threat you have to become like it to an extent. The usual response is resignation and arming ourselves to the teeth. However, there are rare exceptions. Poison gas developed in WWI was unquestionably effective but so horrible that it seems like everyone just quietly decided to abstain from using it and warfare has been a little less miserable as a result. Maybe the inventor of the AA12 should have just kept quiet.


  64. Herb,

    A correction to a sentence above.

    “For energy to be put into a gas through compression and then to produce different projectile velocities BASED ON THE TYPE OF GAS seems very odd.”


  65. Matt,

    RE: Corrected sentence

    Well that is the question…

    The question is based on dynamics. Think of it in a different way. Given an electric car that can go 30 mph on a flat road. Could you run behind and push the car 30 mph? Now let’s assume we rig up a bicycle with a generator. Now you pedal the generator all day to charge the battery. Now that the car is charged it will go 30 mph. You stored the energy slowly by pedaling. The car doesn’t take less energy to go 30 mph on the battery. You just got to take a lot longer to input the energy into the system.

    Imagine that we’re using pressurized water to fire the pellet in one gun and pressurized air in another gun. The pressure in both is 2000 psi. The air will flow faster than water so the gun with air will shoot faster. Think of the water as a super super super heavy gas. The difference between air and helium will be much less than air and water, but the difference is there.

    Does this help?


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