Home Blog  
Education / Training Gamo Dynamax repeater – Part 2

Gamo Dynamax repeater – Part 2

by B.B. Pelletier

Part 1


The new Gamo DynaMax repeater. Gamo product photo.

Before I start today’s report, I have a couple bits of news to pass along. The first regards pellet packing. I learned what is causing the problem many readers have reported this past week. Pyramyd AIR ran out of pellet packing materials for their special packing process about a week ago and have been packing pellets with brown paper as cushioning. Now, most shipments made it through just fine, but some were damaged by rough treatment during shipping. Pyramyd AIR has replaced all damaged pellets that were reported to them, as is their policy, but the sudden change in operations caused a lot of discussion on the web.

They are aware of the problem this has caused and have a rush order for more packing materials so they can get back to their special way of packing, but several hundred orders have already been affected. The volume of pellet orders they process in one week’s time is larger than some other dealers’ quarterly output. I, myself, have an order in for about a dozen tins of pellets, so I’m in line like everybody else.

The shipments packed this way are still in the pipeline and may be for the next week or more. Pyramyd AIR ships over a thousand packages on a slow day, and a lot of those packages contain pellets, so the effect is widespread.

If you receive a shipment from Pyramyd AIR that contains damaged pellets, report it and they will take care of it for you.

Now, on to the next topic. I see that I did a thorough four-part report on the IZH 61 in 2007. There really is nothing new I can say about that rifle, unless you readers can think of something I left out the last time.

What I have not tested is the single-shot IZH model 60. So, that one is due a test, and I plan of doing it for you.

Now, let’s get back to the Gamo DynaMax PCP test. Today, we’ll look at velocity and the operation of the DynaMax powerplant.

Filling the gun all the way
You will recall that I mentioned that the DynaMax fill pressure is 232 bar, which is 3,365 psi. Only three hand pumps currently on the market go that high– the Hill pump, the Air Venturi G4 hand pump (which delivers lower pressure, but only by a hair) and the pump that both Benjamin and AirForce use. The Hill pump and the Air Venturi G4 pump both come with 1/8″ BSPP threads on the ends of their hoses, so the DynaMax fill adapter screws right on. For those with either the AirForce pump or the Benjamin pump, an adapter will be required to connect the pump to the DynaMax fill adapter.

I filled the rifle to 232 bar and began the test. The first thing I was interested in was the number of full-power shots I could get from a fill. Remember, the Gamo literature said there were about 30 shots per fill. I used H&N Baracudas (the same pellets the old Beeman company sold as Kodiaks) and got the following results.

Shot #…Velocity

This performance curve is very close to what I expected, except the high point was higher than anticipated. At 953 f.p.s. the Dynamax is generating 21.38 foot-pounds. Taking a more central figure, like 935 f.p.s., the rifle generates 20.58 foot-pounds at the muzzle with 10.6-grain H&N Baracudas. And there are almost exactly 30 shots, as promised. So, shoot three magazines and then refill with air if you’re using a 232-bar fill.

Filling the gun to 3,000 psi
Since not everybody can fill to 3,365 psi or 232 bar, I promised to also test the DynaMax at 3,000 psi and test another string. I told you that the velocity would not be less, but the number of shots you could get at full power would decrease. Sort of like putting less than a full tank of gas in your car doesn’t affect how fast you can go, only how far. Once again, the H&N Baracuda pellet was used.

Shot #…Velocity

The way I read this, the rifle gets about 16 good shots on a 3,000 psi fill, but there’s no harm with going to 20 shots unless you’re hunting sparrows at 65 yards.

Did you notice that this time the rifle shot four shots that were faster than the fastest shot fired when I filled to 232 bar? Please don’t take this one test and construct a whole new religion from it! Instead, look at what might be causing this result. The rifle may be breaking in. The rifle may be loosening up after sitting dormant in my office for several weeks. If I were to run the test again, the results would probably be different, and we couldn’t draw conclusions from that, either.

The velocity drop-off at the end of the power curve seems to be the same in both tests, which is characteristic of what some powerful PCPs do. The rifle tapers off near the end, then suddenly drops velocity by a large amount and does not rebound from that. Every PCP has its own performance curve, and it seems this is what the test DynaMax does.

Let’s test some other pellets.

Continuing the test
The first pellet tested was the Gamo Raptor. This non-lead pellet has a deserved reputation for going very fast, and I wanted to see how close the DynaMax came to its advertised velocity of 1200 f.p.s. Pretty close, it turns out. The average was 1183 f.p.s., with a high of 1191 and a low of 1169. At the average velocity, this 5.4-grain pellet generates 16.78 foot-pounds of energy at the muzzle.

The Crosman Premier 10.5-grain pellet was next. It averaged 945 f.p.s., with a spread from 931 to 950 f.p.s. It generated an average of 20.83 foot-pounds.

Next, I tried Crosman’s Destroyer 7.9-grain pellet. It averaged 1052 f.p.s., with a spread from 1041 to 1064. That’s an average energy of 19.42 foot-pounds.

Finally, I tested Air Arms domes, which are made by JSB and closely resemble Exacts of the same weight. They averaged 1032 f.p.s., with a spread from 1024 to 1037 f.p.s. That’s an average energy of 19.87 foot pounds.

Other observations
The DynaMax magazine was sticky in the beginning. As I shot the gun more, it loosened up; by the end of this test, the magazine was functioning fine. And this is the easiest magazine I’ve ever taken out of a PCP. There’s nothing that holds it back. Once the bolt and mag release are out of the way, the mag comes out easily.

All pellets fit the chambers of the magazine loosely. So much so that I had to load the gun when it was level if I wanted the last pellet to stay inside the magazine.

Cocking the rifle as a separate operation after loading will take some getting used to. I forgot to pull back on the cocking button several times during this test.

The two-stage trigger-pull is light and crisp. It breaks with just 22 oz., most of which is in stage two, but some of which is in the first stage. That makes stage two feel even lighter. It’s a good trigger.

I’ll test accuracy next. Given the power the gun generates, I’ll go out to at least 40 yards if not 50.

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.

97 thoughts on “Gamo Dynamax repeater – Part 2”

  1. Kevin,

    Re: Skiing, I fully appreciate what happened to you. Last night was my 11yr old's second time on skis, and she's picking it up quick. How do you teach a kid to slow down until they've taken a bad fall???

    Kevin and BG Farmer – excellent call on the finish!

    Frank B – That RLO is good stuff – especially when applied as Kevin recommended. I used it on my R10, which was at the heart of December's discussion. Very likely to use it again, but I'd be very interested in hearing comparisons between it and TruOil.

    As rough as this stock is, I'm not going to jump into another refinish until the summer. I thought I'd give a match a try first – Richmond, VA, 27-28 Feb, CMP Match.


  2. B.B.

    Your reviews of these target rifles – Edge, Challenger, as well as your overall review back in 2008
    nudged me in this direction. Thanks!!!

    I've run 6-7 different wadcutters through it so far. H&N Match 7.56 gave a true single-hole off a bench at 9m. How consistent do you find the same model rifle when it comes to pellets?


  3. B.B.,

    This was an interesting test, statistically. The unbiased Standard Deviation of the first group was 8.44 fps over the first 27 shots with a sample size of 23, with an average of 937.4 fps.
    The second group had an SD of 10.3 fps for the first 13 shots, with an average of 948.5.

    You mentioned that the variances could well be due to the rifle loosening up again after a few weeks of sitting idle.

    Now to my question: If you could totally eliminate the effects of the shooter himself and the environment by clamping the rifle in a frame and shooting in a wind-less range, could, do you think, the Standard Deviation in the size of the group (the holes in the target I mean this time) be correlated to the SD of the velocity?

    If so, one might be able to draw interesting conclusions as to the quality of the pellet or its seating and flight characteristics. The idea is to eliminate to the extent possible the effect of the variables that one can control. If the experiment is then repeated at least three times with inconsistent results, you might instead point the finger at inconsistencies in the performance of the rifle instead.

    Do you think it's feasible?


  4. B.B.

    I got an Avanti 449 and it was everything I had hoped it would be for the first fifty shots. Then it became very erratic. Shots not grouping at all. I reread the manual and it said to drop a q-tip down the barrel while it's breaking in. Q-tips don't fit in the barrel. Can you help with a tip or a recommended kit? It's starting to shoot better, but it's not like it was when I first started shooting it. Thanks in advance.


  5. Matt,

    Check the stock screws cause some times those little rascles loosen up and can cause a gun to become very erratic.

    Also use this blog's search engine and check out barrel cleaning. If you don't have any loose screws you might have a dirty barrel.

    Please get back to us with your findings.

    Mr B.

  6. Jay,
    If you are in SW VA, did you go to Homestead for skiing? Its a neat place.

    I tried to find a real oil-finished 300 on the Yellow forum, where I know I've seen them (at least one), but the search didn't work for me. Since you aren't in a hurry, I would again urge you to consider it — the combination of stippled grip and truly soft sheen was stunning. The one with Tru-Oil looks very nice, but the build and gloss make the target stock look a bit outsized in my opinion.

  7. AlanL,
    I can see your procedure working for a PCP, maybe, but I wonder if it would for a springer since the artillery hold is essential for consistent groups and no one has come up with a mechanical mount to duplicate it, yet, as far as I know.

    WV: sunat. Answer: yes it is all over here.


  8. BG_Farmer,

    I've flown over the Homestead quite a bit, but Winterplace in WV is a good bit closer, and major roads all the way. Lots of minor roads still closed around here, esp to the north.

    While the RLO left a high gloss, the Stock Mud cut that down quite a bit from what was showing in the last photos of my R10. I don't care for the high gloss of the current lacquer finish.


  9. CJr,

    Thanks- I figgered there'd be a fly in the ointment somewhere. Now if only I can perfect my own artillery hold… I remember reading that the kid who won the archery gold medal at the ATL olympics back in '96 even learned to slow his heart rate to the point he could release between beats!


    Who's Herb?

    Back on 2 Sep 09 you wrote, "Speaking of cases, don't ever store any gun in a soft case, or in a hard case that contains a foam liner. These soft materials attract and retain moisture and will rust or corrode your guns as certainly as death and taxes. The only cases that are safe for gun storage are the ones made for that purpose, and even then you probably shouldn't do it."

    So… what the heck do I put 'em in? Just before I read this I went ahead and bought the PY-A-250 Plano hardcase with foam inserts for the RWS 54 and two PY-A-2378 Plano soft cases for the unscoped RWS 34 and Air Venturi Bronco, just for around the house. What now?


  10. AlanL,

    Herb is a reader who would love to have a discussion about statistics with you.

    Why do you have to store your airguns in a case? Is it for home security? So kids won't have access? Because just standing them up in the back of a closet is probably one of the better ways to store them. Cases are for carrying guns, not for long-term storage.

    However, I think Plano uses closed-cell foam that is not hygroscopic, so it's probably okay to store them in one of them.


  11. Hi BB,
    I would be interested in a blog post on how you put together these blogs and magazine articles you do. Do you have a bunch or articles going at once, are most of the multi-part articles done piece at a time or completed ahead of time? How much pre-planning happens before you start a blog post? How many hours of testing and writing does the average post take? I am just interested in the process.

  12. I have a thought… the packaging shortage need not be so bad if PA can figure out a way to get customers to mail back the empty boxes. Maybe a discount coupon or "return 5 boxes and get a free tin of pellets". It has to work out financially for both parties but it would definitely prevent a shortage.


  13. AlanL,

    I agree with BB on storing firearms in cases. I personally don't do it myself preferring the stand 'em in the back of the closet approach.
    Though, I do use silicone impregnated gunsocks that you can find for $5 or so at your local WalMart, BassPro, Cabelas, Gander Mtn, etc. though sadly not at PyramydAir.
    I just slip the gun into one of those before placing it back into my closet. One day, I'll have a proper gun safe, but not yet.

    The gunsocks are made of silicone impregnated cloth that work wonderfully to keep your guns dry and rust-free. It's very similar
    to the silicone cloths
    used to wipe a gun down after a day in the field, except that they get to live there forever 🙂

    I've been doing for years
    with nary a blemish to be found. They also work well with hard cases during travel to protect your gun if the case itself gets wet, and at some point they all will get wet.
    Guns are tough, but their finish simply can't take close contact with significant humidity for long. In the event that a buckle fails
    or some other such occurrence, having them in a gunsock will limit the damage if not prevent it.

    I have a couple of rifles passed down from my Father
    and Grand-Father that were simply stood in the corner by the back door as was the custom, and they are essentially blemish free.
    The only damage was thinned blueing from constant handling. I'm not even sure if they were ever treated to more than just a perfunctory wipe
    with a dry rag after a wet or muddy outing. One in fact was so dirty that it failed to extract about every fourth shell or so, but it still had no significant
    blemishes when passed to my hands. And, it was made in the 1930s to boot. Wonderful technology, guns.


  14. I forgot to mention the one thing almost guaranteed to destroy a gunstock's finish is a slip on recoil pad. My Father put them on his Stevens 311 12 gauge double barrel and Remington 700 some years ago to tame the recoil, and both stocks are in bad shape now. The rubber traps moisture right next to the finish and flakes it all away over time. Not right away, mind you, but they all seem to do it. It's a shame too, because I'd love to sell the 311 as I can't hit snot with a double-barrel for some reason, but the damage from the slip-on prevents me.

    Oh, well, at least we don't have to worry about that little 'innovation' in our branch of the shootin' sports.

  15. B.B.,

    Thanks, yes, both for home security and keeping them hidden from the kids. And, even though I'm anal about window seals and changing my A/C filter every 30 days, I still get an ungodly amount of dust settling over everything, especially in my closet it seems like.

    So, do you think a quick wipe with Ballistol before putting away and several little sugar packs of silica gel in the cases will do the trick?


    I just read your response while reviewing my reply. Thanks for the excellent gunsock idea. I will seek out a few. B.B.: Until I get them, will my idea do for the time being?


  16. Way to go Pyramyd!! I placed an order with Pyramyd on the 3rd, chose standard shipping, and received the order the very next day on the 4th. I placed my order before noon and it only had to go from Ohio to Michigan, but still, you just don't see that quick of a delivery when ordering on-line. Way to go!!

    By the way, I am now the proud owner of an RWS 52 in .22 caliber!! I've only shot it probably 50-100 times and all at close range (aproximately 25 ft)but I've been nothing but impressed so far.

    -Aaron in MI

  17. B.B.

    Yes, I remember the four part series on the IZH 61 very well. I thought the new plan was to test the plastic receiver against the metal receiver. As to the IZH 60, I think we discussed this and concluded that since the air transfer port is at right angles to the barrel like the IZH 61 that there would be no difference. However, I'm always up for hearing more about those rifles.

    Kevin, sorry to hear about your daughter and the skiing accident. Be thankful it's not worse. That's one reason I go only for cross-country when I have a chance–never biathlon though. Does anyone know the shooting distances and target size for the biathlon?

    Aaron in MI give us a report on your RWS 52.

    Knife sharpeners! I am now studying under the 17th generation Yoshimoto bladesmith, Murray Carter, by way of DVD. This fellow is a Canadian who went to Japan after high school and studied the secrets of samurai sharpening for the last 20 years. He's very impressive. I would say that this is another case of a master expounding his knowledge in clear terms and is thus a treasure. He ranks right up there with Jack Dempsey for boxing and David Tubb for shooting. With the aid of the internet those masters are popping out all over the place.

    This guy has set a new standard of sharpness. The slicing of newspaper and the shaving of hair off the arm, he says, is low-level sharpness and he will take us beyond. His test for ultimate sharpness is called the "three-finger test" and is as follows. You place the thumb on the back of the blade and take your middle three fingers and slide the pads carefully ALONG instead of at right angles to the edge. It sounds like a recipe to get cut but that is what the thumb is for along with caution and experience.

    There are subjective tests for sharpness. The very dull will not cut even when enough pressure is applied to make the finger pads white. The very sharp will seem to want to bite into the epidermis at the slightest touch. Your ultimate samurai swords of which this guy has encountered quite a few have an edge with a greasy slick feel as if the edge cannot be grabbed and held; it only slides and cuts. My edges, naturally, failed miserably. But Frank B.'s knife that he sent me definitely had the slick feel.



    Dr. Beeman has now responded to my query for his 'The Blue Book of Airguns'. I bought one at a much more favorable price than the other source I had found in England. Dr. Beeman tells me has one left. Since PyramidAir is out of stock of the 7th edition and apparently not getting any more, I feel I can direct you to his site. In addition, he asked me to post the following in the blog for him:

    "The Lewis and Clark Airgun – Key to the American West" – will be out of the printer later this year. It will be a high end, hardcover only version plus possibly a deluxe version, maybe leather cover. A guess at cost would be about $75.00 retail for regular hardbound, and maybe $150 for deluxe version. There are so many color prints, top grade paper, and the printing run will be small, hence the high price despite non-profit basis. Those persons who wish to put their name on a first notification list at DrAirgun@Beemans.net will be eligible for a pre-publication discount once the price is established."

    Meanwhile, Fred's suggestion to contact Martin Cardew for his book "From Trigger to Target" through his brother's watch website panned out. Since Pyramyd is out of this one too, here's the address:

    If Martin okays it, I will soon post his direct contact info for you as well.


  19. AlanL,

    Herb is a chemist who loves to calculate stastics. Until he appears, all I can say about your results (based on the Idiot's Guide to Statistics) is that you want to calculate your SD as a fraction of 1. A standard deviation of 1 indicates that your distribution corresponds to the standard normal curve used to model complex systems; in other words, your results approximate randomness. That's good. Anything markedly different from 1 suggests that there is some systematic error in your shooting or equipment that can be corrected. Also, your results will be more statistically reliable if your sample size is greater than 30.


  20. Matt, I don't have a steel receiver IZH 61 or 60, so I would be comparing what the plastic receiver does against what I remember about the steel guns. That I have already done in the last report. The steel receiver does better.

    I will test the model 60, simply because I have it on hand.


  21. AlanL,

    The Blue Book, seventh edition has been out of stock at Blue Book for several months. We (I'm one of the writers) are writing an eighth edition right now for release in May.

    Don't worry about the prices changing on the older guns. They seldom change much for the older models. What is nice is all the new guns that make it into the book for each new addition.


  22. B.B.,

    Thanks. I'll get the 8th edition too, why not. Sign me up! I love books. I've collected them for more than 30 years, and I'm out of space. But okay, I can handle one more airgun book!


    Hmmm… I think you may be looking at normalized Standard Deviation? I was referring to the actual SD of the velocities in the sample set. Frankly, I thought the values Tom got were a little high, but I don't know what's normal and have no experience whatever in this field. I know these values were on an admittedly small sample, but the samples were still big enough for the SD's to be entirely meaningful. That's why I love SD, it is so much more powerful than just a simple average or variance.

    I can recommend a nice standalone PowerPoint presentation for laymen on understanding SD (unrelated to airguns though) that stays entirely away from any heavy math. SD is a truly useful and very powerful statistical tool. Check out the presentation at:


  23. To Anonymous,and also BB:::: from last set of blog comments re; Clint Fowler. Sorry, my mouth engaged before my brain. I was thinking of Clint Mckee, up the road from the James River Armory (At the Dulton armory). He does M1 work too. Clint Fowler, as you mentioned is down by Quantico and shoots or used to shoot at the Fairfax VA Rod and Gun Club. He is a master at doing an M1– as you observed. Sorry again if I confused people. I blame old age and events for my condition and a touch of senility.

    Tom did I miss what you learned that the stock of the Bronco is made from?

  24. Matt61,

    Regarding the Powerpoint, it is only a few slides about 4 or 5 clicks in that describe SD in a way that I thought makes it come to life. The rest is rather product specific and relates to laser alignment of machinery shafts. Ignore all that- no need to watch the whole thing. It had been a while since I took a look at it.


  25. Daisy 1894 retro fit background. I decided to purchase a new 1894 rather than refurbish my old one and was extremely disappointed with the new version. No power, no receiver loading port, the hammer was now vestigial and you could probably hang the rifle on a hook using the trigger without it going off on you.
    Very few parts remained interchangeable so the refurbish was on again as well as a challenge to improve the new one.
    Contacted Bucky's Daisy, and picked up some parts and an old "Parts gun". I noticed the diameter of hole in the air transfer tube? (Front of piston) got smaller over the years, three different sizes. (Reduced power cause?) Anyway, in short, this is what I did to improve the new one.

    Replaced the small diameter air tube and all required springs and trigger / hammer parts from the parts gun and cut out small notches in the new receiver halfs for the 'old' hammer to clear it.

    This improved power, restored the hammers half cock safety and action to release the piston, removing it from the trigger. All it has to do now is release the hammer!

    When they eliminated the hammers use and installed the 'wood' stock they cut off the extended receiver half tangs for the hollow plastic stock mount and with it the bigger (old) trigger spring attach point locaton. (Major challenge)
    I picked up a chrome plated, flanged, copper 'toilet water connection tube'. Cut it to the proper length, pinched in the remaining receiver 'frame' tangs a little to seat the tube flange on, put the hammer spring through it and hooked it on the end. I then drilled a hole in the stock for the tube.
    (Watch for mount screw clearance)

    Practical? probably not, but it was a fun challenge and I now have a clean (Mostly new!) wood stock 1894 western plinker that's a pleasure to shoot.

    I was going to make up a small pamphlet and get together with Bucky's Daisy for a parts kit, but they stopped selling it. He said there were a lot of disappointed people with the new 1894.
    I have a few photos of the project.

    Bob M

  26. Jay,of course…that was your stock!Duh…..when I post pics of my FWB 124 wearing it's new sunday clothes,you'll understand why I didn't notice anything else on the blog around the crash course on finishing.At that time I had zero experience.Now I can tell you first hand….RLO builds slower and penetrates way deeper IMHO.I ended with Tru-oil….it gave the appearance of a glass coating,at the expense of a plastic feel.I will be working the gloss down to a sheen,maybe the plastic feel will go away…I don't know.

  27. Matt61,I am humbled to be compared to a learned master.I would have come with my "A"game,had I known…I have a stone or two that I use AFTER shaving edge is achieved! Frank B

  28. Matt re:499

    Check to see if the barrel came loose. The barrel on a 499 is threaded and can come loose. Mine did. Just try to finger tighten the plastic funnel cap at the muzzle.


  29. Edith,every word of that post was the gospel truth!You are right that people will think you are a kook,but WE know the truth…I am an extremely logic based person,cynical at that…..but what happened flies in the face of logic!!!

  30. Ken, I must admit the target results I got with the China made springer had a lot to do with with BBs artillery hold. Sure it jumps when fied but a relaxed grip seems to prevent a pivot point from developing during the cycle.

    The Evanix is loud but not too sharp. Sounds good but may upset close neighbors.
    I really like this semi-auto Rifle.

    A "Depinger" for the Condor?
    Is that the term used for parts modified with an O ring addition? or…. the use of a 12" barrel? The metalic ping is more pronounced in a quiet mode.

    Bob M

  31. For the re-finishers who are sharing, here's my current project for your amusement:
    The first picture is the original Traditions Kentucky kit as I assembled it, and the rest are today's trial assembly. Mainly I decided to try everything I could on the lower cost kit before getting a high end one, plus it is a nice little rifle to shoot, so I wanted to correct the architectural features I felt I had left undone.

    Not perfect, not even close, so you can say whatever you want:). The cheekpiece and splice between two stock halves as well as an in-fill in the triggerguard area, for example, were made from a discarded wooden folding chair I'd been keeping for just such an occasion. The finish is more of a paint job, because the two stock halves didn't match at all (a detail I had forgotten), so I decided to have fun with it. Hand-rubbed oil finish next time, Kevin, I promise:). Of course, I tried to present the photos in a somewhat flattering light, so if you think its ugly now, you should see the flash closeups:).

  32. Standard Deviation can be thought of as the average distance between any one observation and the mean or average. While not technically correct, it'a a good concept to keep in mind. SD does not indicate the type of distribution you have (normal or not), but if it's normally distributed, you can expect 68% of the observations in a sample to be within 1SD of the mean and 95% within 2SD.

    The first shot string BB posted this morning (ending with 919fps) is far from normally distributed (bi-modal). When you consider a PCP is a complex system with a valve reacting to changing pressure in the reservoir, it's not too surprising. OTOH, I would expect a string from a springer to be normally distributed. (looked back a ways – didn't find a convenient string to check).

    To put SD into our context, I ran 10 shots from my R10 across a chrony. The average velocity was 908 fps and SD was just under 5. Based on that sample, I'd expect 68% of my shots to be between 903 and 913fps, and 95% between 898 and 918fps. You can do more with SD, but the description will get a bit more complicated.

    Our chrony's calculate a Sample Standard Deviation. The Sample SD corrects for sample size in such a way that a small sample (as small as 5) will give a reasonably good estimate of the true SD. 10 is certainly a better sample size, but going to 30 doesn't improve the quality of the SD estimate much if the distribution is close to normal.

    SD can be turned into Coefficient of Variation by dividing it by the mean. That fraction gives you an idea how great SD is compared to the average. For my string, CV would be .005.

    Frank B – That's good to know! I'll stick with the RLO, as I'm not looking for the Glass type finish. Have you given JM's Stock Mud a try for cutting your finish? I believe Kevin suggested adding a polishing compound to it.


  33. BB,
    Thanks, but I'm not sure I understand the reference, unless you are looking at the first picture (before) or I missed some overall visual impression from being so close to the work.

  34. BB, Your right, it may be an interesting story even if there isn't much interest in actually doing a Daisy 1894 conversion now.
    I would have a problem resurrecting the project in that most of the detailed photos are locked in a computer that only displays a red page now and I have reverted back to a very restricted web tv sevice.

    However I do have a digital camera (It would require a download device for webtv) and the few pictures in old e mail attachments. I need a new computer anyway.

    It may take a little while, but I'll look into it. Send me a contact address and I'll try to send you a few photos for

  35. BB

    Re the Benjamin Hand Pump, do you know where to get additional hose (length) ? I assume that the stock hose could be disconnected at the base, and an "extension+ could be made with male/female fittings?

    Most reviews on the Benji pump are negative on the stock hose length, which appears to be about 12" or less? I can see why, who wants the gun laying on the floor!?

    Brian in Idaho

  36. AlanL,

    RE: Statistics…

    I can't resist the question "what do you think…" 😉

    Question: "If you could totally eliminate the effects of the shooter himself and the environment by clamping the rifle in a frame and shooting in a wind-less range, could, do you think, the Standard Deviation in the size of the group (the holes in the target I mean this time) be correlated to the SD of the velocity?"

    Perhaps. The shape of the group could also be important. The interaction between gun and pellet is so odd that any firm prediction is impossible. The only option is to experiment.

    Also holding a pellet gun in a vise is useless for anything but a PCP. A PCP has another problem. If you overfill the PCP the velocity first goes up (on average…) after each shot, then drops. Such a pattern is counter to the notion that each shot is statistically independent.

    RE: "quality of the pellet or its seating and flight characteristics"

    Absolutely! That is the whole notion behind bench shooting. You're trying to test the effect of the shooter, the pellet, seating and so on. Comparing one type of pellet to another is absolutely a valid endeavor. You just have to be careful and use enough shots to get a statistically valid sample. A three shot group with each of two types of pellets is unlikely to be enough.

    The whole idea is to get a sample for a "standard" shooting setup. You then change something. If the new setup is better than the old, then the "new" setup becomes the gold standard. If not you go back to the current standard setup.

    There are statistically methods where you can vary more than one factor at a time. But such a discussion is way beyond anything that can be done through responses to this blog.

  37. I just ordered a Hammerli 850 AirMagnum. I'm wondering if there is a valve I can put b/t the rifle & the 88 gram AirSource cartridge to both relieve pressure on the rifle's seals & preserve CO2 in the AirSource cartridge? I've seen a pack containing 1 Crosman AirSource cartridge & 1 valve of some kind, but it seems from the packaging that the valve just releases air from the cartridge, which doesn't make sense (since just unscrewing the cartridge does that).

    Any help on finding such a valve?



  38. Brian,

    Believe me, you do NOT want a longer hose!

    The hose has to be brought up to pressure before the gun starts to accept air and nobody wants a long hose. The shorter the better, within reason. Not only do you pump a lot more with a long hose, when you use a scuba tank with a long hose you waste a lot more air when you bleed. Short hoses are preferred and short microbore hoses are the best.

    A 12 inch hose is pretty much what everyone uses. I don't know who is objecting to short hoses, but everyone I shoot with prefers them.


  39. BB

    Re Short Hose on Hand Pump

    Makes total sense, small diameter I.D. hose X short length.

    Lot's of pressure with lower volume, right?

    Come to think of it, my old AA Shamal set-up was only about 8" long from the Scuba Tank to the rifle.

    Brian in Idaho

  40. Well. I never thought of the longer hose/more air bled effect. I will,
    henceforth, quit cussing and embrace my short hose as I cup Ms. M in
    my left hand and twist the knob with my right.

  41. Jim,

    Is this what you are looking for?

    The problem is that you need adapter(s). The above on/off valve has standard paintball threads while the RWS 850 has the 88 gram AirSource threads.

    What a lot of 850 owners do is purchase the 88 gram to paintball adapter from Bryan & Associates made for the 850. Then they use a 9 oz paintball CO2 tank instead of an 88 gram tank (or they use an HPA [High Pressure Air] tank).

    You can find more details at The 850 Resource.


  42. When I fill the Marauder I can cradle it by placing the fingers of my left hand between the scope and the rifle with the rifle upside down so I can see the manometer. It balances well that way and it's easy to hold while turning the tank valve with my right hand and disconnecting with the right hand. The only hard part is connecting the hose because the rifle has to be perfectly in line with the connector in order for it to latch properly.

    Hah! WV: rested – I'll say!!!

  43. Bob M,

    Thanks for the comments on your Evanix Renegade! I am considering buying one and was wondering how loud it is and what the quality is like.

    My understanding is that it is a double action and not a true semi-auto.


  44. RE: Statistics

    Should have pointed out another obvious analysis that could be done.

    You can calculate how much the pellet drops due to gravity going to the target. You can then use the variance in the FPS of the muzzle velocity to see how much of a factor the muzzle velocity plays. Unless the variation is excessive, the factor is typically minimal.

    This of course also depends on quality of gun, the skill of the shooter and so on. I shoot "patterns," not the one-hole groups that so many of the good shooters here can do. So FPS variation in muzzle velocity is usually the least of my problems. For a really good 10 meter shooter, it will make a difference. That is why they shoot with $2,000 rifles, not the $80 Daisy 22Sg that I like. 😉

    It is really fun to plug numbers like this into a program like ChairGun and play what-if games….

    Obviously in the string that Tom shared, shot 24 at 876 fps would tend to impact lower than shot 10 at 943 fps.


  45. A.R.Tinkerer,
    Just remembered, I installed a ported Muzzle Brake on my Evanix Renegade and it may be taking the edge off the noise. One is made just for it, but I had another already that just needed some metal tape to center it.
    Another POI, there are two types of cylinders out there for this rifle. Both have a land in each bore to keep the pellet from falling out the back, only one is shallow and will not accept long pellets like the EUNJIN. I ordered spares (AR6) and they came with the long bore.

    If AR Tinkerer means what I think it does, you might get a kick out of a RAM A4
    duplicate Colt paint ball marker in.43cal that has a BB conversion kit (airsoft as well) and is "Select Fire".(Expensive)

    You know I keep getting mixed up on single/ double action. You figure a 'single' trigger pull that rotates and fires would be a 'Single' action….Cocking and then pulling the trigger would be 'double' action !! But when the gun does it, it's reversed!

    Call it double action or semi-auto, If your not all that fired up to hit an exact spot, the Renegade will put 6 shots on a target as fast as you can pull that trigger, and I would hate to be on the receiving end of 6 Eunjins!

    Bob M

  46. A.R. One other point because of the lands in the cylinder you need to push the pellets home head first, push them back out and reinstall them skirt first. It's hard to fit most pellets in skirt first without squeezing them down first….Get spares!

  47. Day from hell.

    Pain with my daughters leg. Off to the doc first thing. No major problems.

    Woke up cold since the boiler shut down.

    First boiler guy was here for 3 hours. Next boiler guy arrived at 5:30pm and didn't finish till 7:00 pm. Still not fixed. Spark plug/ ignighter on this hydropulse boiler takes a special tool for extactraction that costs $190.00 and the company only has one and its on another truck. #@%$^!

    On top of this my computer caught a viris from photobucket.

    My wonderful IT gifted wife spent 3 hours tonight scrubbing my computer to get rid of it.

    If I ever find the 12-15 year old son of a dog that spreads these virus's on the internet instead of mowing lawns, having a paper route, shoveling snow, etc. I'll put my boot up his backside.

    Nice day.


  48. AlanL,

    Listen to B.B. and Bobby Nations. Buy a silicone impregnated gunsock if you must store your guns in a case. Foam lined cases are the worst for storing guns.

    Find another storage method but in the meantime if you must store them in a case put a gunsock around your guns first.

    Look on ebay. Gunsocks are cheap.


  49. Kevin,

    Glad your daughter's better.


    Thanks for your observations. Maybe after I've shot a few thousand pellets through my RSW 54 I'll get good enough that I can trust myself to start playing with a crony and measuring a few things. It would be fun to consistently pinpoint different problems just through careful analysis of performance. But I agree that this may never be possible with a springer.

    B.B., this blog is highly addictive. It should come with a warning label. I need to get out there and shoot more!


  50. Matt61,

    Thanks for your thoughts about my daughter.

    She'll never be a cross country skiier. She needs stimulation like her dad.

    She was driving the atv's when she was 5. I had to be behind her since she could press the hand break and could reach the break on the floor.

    Love this kid since she's like me.


  51. BG_Farmer,

    I really like it. The finish is terrific.

    The darker side is magnificent.

    I must have missed the explanation as to why there are two sides to that fine blackpowder rifle.


  52. Frank B and those few other collectors of fine, vintage airguns,

    I have a line on a .20 caliber R9 Limited Edition (I think there were 110 made) in blue laminate with the beeman inlay on the pistol grip that I think signifies it as among the first run. Serial number 102. This has paperwork showing that it has a Black Venom/Viper tune done in 2001.

    I wouldn't put much stock in the tune at this point since it didn't seem to smooth out the firing cycle and even the owner can't shed light on what a black venom/viper tune is or even who did it even though he has the paperwork.

    Rare gun nonetheless and asking price is $825.00 and includes a scope (leapers 6-24×50) and rings.

    I'm considering it but if you're more committed than me I'll put you in touch with the guy.



  53. Kevin,
    Thanks. I think the lighter finish is the "before" picture when I put it together last summer, and I just wanted to try something new this time with the finish, plus needed camouflage for the wood splices,etc. If not that, maybe its just my poor photography:)? It's not a masterpiece, but it does look pretty good and evenly toned in real life. I'm glad you got a look at it, because I felt dishonest, having promised to try a non-poly finish, which turned out to be impractical. Next one will be at least a monolithic piece of maple or cherry, which should make a non-synthetic finish possible:).

    Sorry to hear about the bad day, seems like one of those times: forsan et haec olim meminisse iuvabit. Feel free to rid the earth of virus writing punks, our online Windows play machine is still crippled somewhat from fixing a stupid fake antivirus virus. Ironically, the viral anti-virus was much more efficient than our real anti-virus programs:).

  54. Tom,
    Hope it is OK to go off topic here…

    I know you are a big fan of both the Benjamin Marauder and the AA TX200. I currently have a Crossman Quest 1000 and have been bit by this air gunning bug.

    Getting smaller and smaller shot groups is what I find exciting about this sport and want to hone my skills enough to begin shooting FT. I am wondering about two things:

    How much of an accuracy difference will I see with an upgrade from my current rifle?

    What advice can you give in choosing between the two rifles mentioned above? I feel like I am trying to pick between apples and oranges.

    Thanks for indulging me if you should choose to do so…


  55. Bob M,

    Thanks for all the Renegade info! I was thinking the same thing about 6 shots with Eunjin pellets – I would love to feel how it shoots!

    The name "A.R. Tinkerer" refers to "air tinkerer". However, I don't have a wide range of experience yet, just the RWS 850, Crosman 13xx/22xx and Crosman 622. Intend to eventually play with compressed air engines someday.


    Sorry to hear about your daughter's injury! Hopefully she'll heal up before she gets used to her newly found kingdom 🙂


  56. Kevin- I think Ken may be one of those cyber gremlins that escape from my remote keyboard unnoticed when the batteries get low … or just the results of my "CRS" syndrome having just talked to a friend of mine with that name on the phone.

    I just knew there would be a price to pay for 20 years of good duty stations in the USN !

    Bob M

  57. B.B.,

    Great review so far. It's a shame about the 232 bar fill. There is no power adjuster right? At least if it had one one may be able to regain some shots @ a lower power. I'll be waiting for the accuracy test & the .22 version, The .22 should be more efficient.


  58. A.R. Tinkerer
    This article may help you decide on an EXANIX Renegade. It's actually listed as an AR6 there,

    He throws in some good words about PA too.
    Bob M

  59. Scott,

    Yes, a .22 PCP is always more efficient than the same gun in .177. I don't know if I will be testing a DynaMax in .22 or not, but through interpolation we can estimate that the power will be at least up in the 25-28 foot-pound region.


  60. Mark,

    So you are bitten by the bug and ready to move up? Well, you've chosen two wonderful rifles to pick from.

    The TX 200 is more of what you are already used to. It will amaze you with smoothness, a wonderful trigger and accuracy. But it's still a springer like your Quest.

    The Marauder takes you into an entirely new world. The artillery hold is still useful, but nowhere near as important with a PCP. And the support tail that goes with PCPs (tanks, adaptors, fill levels etc.) is unknown in the springer world.

    So what do you like the most–the feel of shooting or hitting the target? If you like the feel of shooting, get the TX 200. If you like hitting the target, get the Marauder.

    The TX with great care and good form can shoot half-inch groups at 50 yards on a calm day. The Marauder does that and more much more easily.

    Since you have been bitten by the bug here is one thing I can tell you. Eventually you will own both rifles.

    So the question isn't which one should you buy. It's really which one should you buy FIRST.

    And if you don't already own a chronograph, better think about getting one soon.


  61. B.B.

    Thanks for the response. And for me the answer is definitely hitting the target.

    Now just how big an accuracy difference will I see going from the quest to the Marauder? While I did put a Charlie da Tuna trigger into the quest and it made a huge difference once adjusted well, I just never see any reviews of the Quest to compare the accuracy to the higher end models.

    Thanks once again.


    PS Thanks for all of your articles. Studying you writings has been a wealth of information.

  62. B.B.

    Oh yeah. One more question. Pump vs Scuba. I hardly every hear anything about the pump. Is that because Scuba is the way to go?

    I was reading in the Marauder manual that leaving a charge in the tank is a good thing. So after the initial charge, how difficult is it to top it back out?


  63. Mark,

    How small a five-shot group can you shoot with your Quest at 50 yards? Compare that to a group that's smaller than one-half-inch. That is as close as I can get to telling you how the Marauder compares for accuracy against your Quest.

    If you are an average shooter, the Marauder will be more accurate and the accuracy will increase as the distance does. If you are a careful shooter the Marauder will be enormously more accurate at all distances.

    As for hand pumps, I'm someone who uses them. Today's report was done by filling the rifle from a Hill pump. I did it because the Hill was the only fill device I had that could accept the Dynamax fill adaptor.

    A scuba tank is easier to use than a hand pump, I'll say that. But for a real treat, get an 88 cubic-foot carbon fiber tank that will fill your gun full nine times as many times as an 80 cubic-foot 3,000 psi scuba tank.

    As far as leaving a charge in the gun, that's something you ALWAYS do with PCPs. You never shoot out all the air.

    So every fill of a PCP is from the point where you stopped shooting to the maximum fill point. Usually a rifle that takes a 3,000 psi fill will drop off the power curve at about 2,000 psi. On some rifles like the AirForce rifles, it may be as high as 2,200 psi.

    So you are adding only 800-1,000 psi each time you fill the gun.

    If you are using a hand pump you will be filling at the most difficult part of the fill–from 2,000 to 3,000. If it was from zero to 1,000 or even 1,000 to 2,000, it would be much easier.

    I find that pumping over 2,500 psi is hard, but I have watched many other people pump and I have to say that anything over 2,000 psi is hard for most people.

    I use this analogy. If you enjoy walking behind a lawnmower, you can use the pump. If you own a riding lawnmower and mow less than three-quarters of an acre, get a scuba tank. If you hire others to mow your lawn, get a carbon fiber tank.

    Have you watched my video on the hand pump?



  64. B.B.

    Love the analogy! I walk behind the lawnmower and then go running for 3.5 miles.

    Thanks for all of info and I will be sure to watch the vid when I get home today.

    Best Regards,
    Mark B.

  65. BB, as I remember you tested the B40 against the TX200 some time ago and found the accuracy comparable… but these days you don't seem to be recommending it. Is there some reason you've soured on that rifle?

    Mark, I don't know what sort of accuracy you get out of your Quest… but I've owned several Quest variants (the Phantom, Storm XT and Sierra Pro), and the BEST any of them would ever do in my hands was about 3.5" at 60 yards for 9 out of 10 shots (I allow myself 1 flier). The best I was ever able to do was about 1.5" with my RWS52, although my 46 Stutzen, 300R, and CFX were all able to hit under 2".

    Now obviously I'm not a very good shooter, but this should give you a relative idea of the accuracy of different springers. Also note that ALL the best guns are fixed-barrel types. My best with a breakbarrel was 2.02" with an old Beeman 250 (RWS45) and 2.03 with an RWS350.

  66. I suspected as much. I got that impression from every fairly recent model out of that factory that I've tried. That seems a bit odd – given that their main rival (Shanghai) has been improving their quality in recent years.

  67. Where can I download and print out an exploded view of an older Daisy model 25 pump bb gun. I took mine apart and forgot what goes where and how it fits. Admittedly, a folly on my part.

  68. I'm the guy that asked about the CP99 on the July 06 blog and was told to ask on the latest so here goes. I bought the H&K P30 just because I liked the looks of it on the web site, know I should have gotten a cheaper one for my 1st CO2 pellet pistol but it just grabbed me. Got it in late today along with a UTG Tac Laser. It is in the 20's at night and the 40's in the day so don't know when I will get to use it much, I did get to shoot 1 mag out the back door before it got dark and I mounted the laser. 8 shots all over a 10 X 14 box, really bad shooting. I'm a newbie with air guns so don't know what to really look for in a gun, never have seen a "real" P30 but don't think it could be too much nicer than this gun, love the look and feel. I have some Daisy Percision Max pellets so thats what I will be using, just need practice and learn to shoot a pistol. By the way it says in the manual that frequent use of BB's may wear the rifling, so no BB's. I ordered 1 pk of extra mags and they sent 2. Now to learn to shoot, 1st impression from a newbie is that it is a very nice gun. Steve

  69. Steve,

    you're getting closer! But you published your comment on last week's blog! Here is the link for the current blog:


    Steve, by all means, read the old blogs. You will learn a marvelous amount about air guns. If you also have the time, read the comments as many times, there are real gems in here.

    However, here's what you should know. First, CO2 is very sensitive to temperature. As you shoot rapidly, the CO2 cylinder cools (Bernouli's principle) and the cooler temperature lowers the pressure of the CO2 coming out. Lower pressure equals lower velocity equals lower point of impact (POI), So for the utmost in accuracy, you need to wait several seconds between shots.

    Next, differnt guns like differnt pellets. That P30 may shoot more accurately with JSB's or Crosman Premiers or RWS Super H's. You get the idea. To figure out where the gun is shooting and what pellets it likes best, rest the gun on a solid surface and take your time aiming so you have the same point of aim every shot (POA). I would think that at 5 yards, you should be able to put together a 5 inch group. However, CO2 pistols are not forte.

    So, post this on the current blog and lets see what type of help you get from the experts.

    This pistol that you bought is a fun, plinking type gun good for killing aluminum cans and punching holes in targets.

    Fred PRoNJ

  70. SteveJ,

    Welcome to your new world. Glad to see that you're trying to get in some trigger time. My range is under 2-3' of snow. Stll cann't see the back stop,etc.

    By the way, you almost got to the current blogwhich is always found at/blog// Please join us there and share your impressions of your new pistol.

    Mr B.

  71. I guess I was thinking when I clicked on blog on the Pyramyd catalog site that it took me to the latest blog but I guess not. What do I have to do, go to the blog list and click on the bottom one? I thought this one said 16 Feb, so what is the correct procedure to get to the latest blog when I click on the blog name at the PA gun mall? Steve

  72. Steve,

    It sounds like you have the home page cached in your computer's memory. So the blog link took you to what had been the latest page on the day the home page was cached.

    The address people keep giving you is where the current blog always publishes. On Friday, the blog remains current until Monday morning at 6:30, Eastern, when a new blog is published. At that time the Friday blog gets it's own special address that it keeps from that time forward.


Leave a Comment

Buy With Confidence

  • Free Shipping

    Get FREE shipping on qualifying orders! Any order $150+ with a shipping address in the contiguous US will receive the option for free ground shipping on items sold & shipped by Pyramyd AIR during checkout. Certain restrictions apply.

    Free shipping may not be combined with a coupon unless stated otherwise.

    View Shipping Info

  • Shipping Time Frame

    We work hard to get all orders placed by 12 pm EST out the door within 24 hours on weekdays because we know how excited you are to receive your order. Weekends and holiday shipping times will vary.

    During busy holidays, we step our efforts to ship all orders as fast as possible, but you may experience an additional 1-2 day delay before your order ships. This may also happen if you change your order during processing.

    View Shipping Times

  • Shipping Restrictions

    It's important to know that due to state and local laws, there are certain restrictions for various products. It's up to you to research and comply with the laws in your state, county, and city. If you live in a state or city where air guns are treated as firearms you may be able to take advantage of our FFL special program.

    U.S. federal law requires that all airsoft guns are sold with a 1/4-inch blaze orange muzzle or an orange flash hider to avoid the guns being mistaken for firearms.

    View Shipping Restrictions

  • Expert Service and Repair

    Get the most out of your equipment when you work with the expert technicians at Pyramyd AIR. With over 25 years of combined experience, we offer a range of comprehensive in-house services tailored to kickstart your next adventure.

    If you're picking up a new air gun, our team can test and tune the equipment before it leaves the warehouse. We can even set up an optic or other equipment so you can get out shooting without the hassle. For bowhunters, our certified master bow technicians provide services such as assembly, optics zeroing, and full equipment setup, which can maximize the potential of your purchase.

    By leveraging our expertise and precision, we ensure that your equipment is finely tuned to meet your specific needs and get you ready for your outdoor pursuits. So look out for our services when shopping for something new, and let our experts help you get the most from your outdoor adventures.

    View Service Info

  • Warranty Info

    Shop and purchase with confidence knowing that all of our air guns (except airsoft) are protected by a minimum 1-year manufacturer's warranty from the date of purchase unless otherwise noted on the product page.

    A warranty is provided by each manufacturer to ensure that your product is free of defect in both materials and workmanship.

    View Warranty Details

  • Exchanges / Refunds

    Didn't get what you wanted or have a problem? We understand that sometimes things aren't right and our team is serious about resolving these issues quickly. We can often help you fix small to medium issues over the phone or email.

    If you need to return an item please read our return policy.

    Learn About Returns

Get FREE shipping on qualifying orders! Any order $150+ with a shipping address in the contiguous US will receive the option for free ground shipping on items sold & shipped by Pyramyd AIR during checkout. Certain restrictions apply.

Free shipping may not be combined with a coupon unless stated otherwise.

View Shipping Info

Text JOIN to 91256 and get $10 OFF Your Next $50+ Order!

* By providing your number above, you agree to receive recurring autodialed marketing text msgs (e.g. cart reminders) to the mobile number used at opt-in from Pyramyd AIR on 91256. Reply with birthday MM/DD/YYYY to verify legal age of 18+ in order to receive texts. Consent is not a condition of purchase. Msg frequency may vary. Msg & data rates may apply. Reply HELP for help and STOP to cancel. See Terms and Conditions & Privacy Policy.