Some precharged pneumatic basics explained

by B.B. Pelletier

Before we start, I have another plug about the Friday Facebook event from 10 to 11 a.m., Eastern. I’ll be answering airgun questions on Facebook on this Pyramyd Air Facebook page. To see the discussion, you must have a free Facebook account. You do not have to be a recognized Friend of Pyramyd Air to ask a question.

If you want to set up a Facebook account, register on the link provided above. Once you have an account, sign in and then click on the link above once more to go to the page. Please join me on Friday, if you’re able!

Today, I want to explore some of the basic facts about precharged pneumatic operations, because I sense the time is right. Let me begin with the term precharged pneumatic.

What is a precharged pneumatic airgun?
A precharged pneumatic (PCP) is an airgun that is filled with air and then shot many times before refilling. Compare that to a multi-pump pneumatic that is pumped many times by a built-in pump and then fired just once. To take another shot, the multi-pump has to be pumped up all over again.

Big bores
How many shots each precharged pneumatic gets on a single fill of air depends on just one thing: How much of the stored air is used for each shot? Big bore airguns use incredible amounts of air and, therefore, get very few shots per fill. A Quackenbush .457 Long Action rifle gets two good shots per fill; on mine, the max fill pressure is 3,500 psi. After the second shot, the gun is down to 2,200 pounds per square inch (psi). My rifle gets about 560 foot-pounds of muzzle energy on the first shot and 490 foot-pounds on shot two.

A .50-caliber Career Dragon Slayer can get 5 good shots on a 3,000 psi fill. That rifle generates just under 200 foot-pounds on the first shot and drops off to about 120 foot-pounds by the final shot. And, once again, the pressure in the reservoir will be down to somewhere around 2,000 psi when you’re finished. Exactly where it will be depends on how many shots have been fired.

That should answer another question that’s often asked: Should you get a scuba tank or a hand pump to fill a big bore? The answer is “neither.” To fill a big bore airgun, you really need a carbon fiber tank. I will explain all of this, but right now I need to back up, because this is report is supposed to be basic.

What is a hand pump?
A modern high-pressure hand pump is a mechanical pump that enables a shooter to fill a pressure vessel with air compressed to a very high level by muscle power, alone. Being mechanical, the pump requires effort; and, as the pressure increases, the pumping effort increases with it. From zero up to somewhere above 1,500 psi, the effort is relatively easy and most able adults will have no difficulty pumping. Above about 1,500 psi is where the effort starts to become noticeable. When I say that, I shudder because people come in all shapes and sizes and there is no such thing as a standard person. So, perhaps I should say that above 1,500 psi is where I begin to notice an increase in effort. I once watched an adult woman struggle to pump over 1,600 psi, so please take what I say in that light.

Also, hand pumps fill guns slowly. Think of this. At the tire store the hydraulic lift hoists your car rapidly and with great ease. Now, you try to do the same thing at home with a hydraulic hand pump bought at the hardware store. It goes a little slower, wouldn’t you say? That is the difference between filling an airgun from a tank and filling it from a hand pump. If all you need to do is change one flat tire, a hydraulic hand pump is a great little tool. But if you’re running a tire store, you want to have five or six bays, each with its own hydraulic lift. If you’re going to be a serious PCP shooter, you will need serious air.

It can take 100 to 150 pump strokes of a hand pump to fill a big bore air rifle reservoir. It all depends on the size of the rifle’s reservoir.

A big bore gets two to five shots from a fill and drops down to 2,200 psi in the reservoir, then it has to be filled up to between 3,000 and 3,500 psi to shoot again. That happens to be the hardest place for a hand pump to operate; and if it takes 100-150 pumps to refill the gun, what do YOU think about using a hand pump on a big bore? Maybe, only if it’s your absolute last alternative? And, yes, I have done it a couple times.

Refilling a smallbore PCP
A smallbore air rifle comes in any of four calibers: .177, .20. .22 or .25. While there are still a great differences among these guns in the amount of air they use per shot, none of them uses anywhere near the amount used by a big bore. So, a smallbore gets many more shots per fill than a big bore. The most powerful guns of the bunch get the fewest number of shots because they use the most air. The AirForce Condor is one of the most powerful factory-made smallbores and has a special valve to extract the maximum number of powerful shots per fill. It also has one of the largest air reservoirs on the market. A Condor can get about 20 shots on a single fill when the power is set to its maximum.

Stepping down in power to an Air Arms S410, you may get up to about 35 or even 45 shots on full power. The actual number depends on the distance at which you’re shooting and the velocity variation you can tolerate. Given that many shots, a hand pump may be a viable option for the shooter who is in shape, doesn’t mind a little work and takes a while to shoot all those shots.

But in 2008, Benjamin brought out the Discovery rifle. It’s a low-cost PCP that operates on just 2,000 psi. It’s much easier to fill from a hand pump than most of the guns on the market. The Discovery gets about 25 shots from its fill. Not only is the work easier, but there are also a decent number of shots when you’re done. The Discovery is a PCP that’s designed to be filled by a hand pump. But if you use a scuba tank to fill one, you’ll still be able to fill your Discovery all the way after other PCPs have drained the tank to the point that it needs to be refilled. That’s another bonus.

A scuba tank
We talk about scuba tanks as though they are all the same, and they aren’t. They come in different sizes and have different fill pressures, all of which affects the amount of air they contain. One very common scuba tank is an aluminum 80-cubic-foot tank. That means that the tank holds 80 cubic feet of air, not that the tank has an internal volume of 80 cubic feet. Since air compresses, what they are talking about is the number of cubic feet of air at sea-level pressure that is being filled into the tank. Since this particular scuba tank is rated to 3,000 psi, it can hold 80 cubic feet of sea-level air, when that air is compressed to 3,000 pounds per square inch (psi).

The pressure of air at sea level is about 14.56 psi. That number divides into 3,000 just about 206 times, so each cubic foot of air is being compressed about 206 times to get 80 of them into this scuba tank. By the way, that’s where the pressure unit bar comes from. So, 206 bar equal 3,000 psi.

There are other types of scuba tanks. I have a couple little ones that hold only 6 cubic feet of air at 3,000 psi. They’re used just to top off a gun during a match or when hunting. There are 120 cubic-foot, 3,500 psi steel tanks that aren’t much larger than an 80 cubic-foot aluminum tank. Because they’re steel, they hold higher pressure safely, so the same volume holds half again as much air (120 cubic-feet compared to 80 cubic-feet). I used to own a scuba tank that held air pressurized to only 2,200 psi. It was useless for filling most PCPs, with the exception of the Benjamin Discovery. So, don’t think that all scuba tanks are the same.

Carbon fiber tanks
A carbon fiber tank is a breathing tank that is not for underwater. They’re used mostly by rescue workers such as firefighters. Like scuba tanks, they also come in sizes, although their fill pressures tend to not vary as much. An 88 cubic-foot, 4,500 psi carbon fiber tank holds only 8 cubic-feet more air than an 80 cubic-foot scuba tank, but it does so with a very important difference. Since the carbon fiber tank is pressurized to a higher level than a scuba tank, it has more high-pressure air available. Consequently, there are a great many more full fills for any given gun in one of these carbon fiber tanks than in a scuba tank. You might be able to fill a PCP to 3,000 psi two times from a 3,000 psi scuba tank, and after that the next fill might end at 2,975 psi. After that you’ll stop at 2,925 psi, then 2,850 psi and so on.

But, a carbon fiber tank that’s pressurized to 4,500 psi will continue to fill a PCP to 3,000 psi many times. Perhaps, as many as 18-20 times, depending on the gun. So, we say the carbon fiber tank has about nine times more full fills in it than in a typical scuba tank. That’s why the carbon fiber tank is so valuable.

Carbon fiber tanks have an aluminum bladder inside the carbon-fiber winding. Since the carbon fiber strengthens the bladder so much, the aluminum can be thinner and yet withstand even greater pressure. Therefore, an 88 cubic-foot carbon fiber tank weighs only about half as much as a scuba tank. That’s a lot more full fills for your guns at half the weight. What’s not to like? Well, there’s the additional cost of the more expensive carbon fiber tank; but if you can get past that, there are very few reasons not to get one.

Why higher air pressure doesn’t make your PCP shoot any faster
Think of a PCP gun as a car. Put in the correct fill, let’s say 3,000 psi, and the gun shoots fine. As the pressure drops it still shoots fine because that is how it is engineered to operate. Fill a car with gas and it will go far and fast. But, try though you might, you cannot put in five more gallons of gas than the tank is designed to hold. Even if you could, the car would still go the same speed. It’s not designed to go any faster.

Put a longer barrel on a PCP and it probably will shoot faster, just as taller tires will make a car go faster. But there are limits. Too long a barrel is ungainly, just as too-tall tires handle poorly.

How many shots can I get?
This question commonly comes from someone who is looking at their first purchase of a PCP with the same enthusiasm as an insurance underwriter looks at smokers’ lives. Do you want the baritone to sing a moving song or are you just interested in how much of the alphabet he can burp?

What I mean by that is this. Shooting accurate shots is a goal. Hunting with clean kills is a goal. Shooting a PCP for as long as it will still poop out a pellet is a college prank. There’s no useful purpose to that number, but a nickel-sized 75-yard group is appreciated by everybody. Find out what the gun you want will really do by asking those who really do it on a regular basis. Forget the online wizards with their tin-can technology and witches-brew lubricants that promise you Nirvana for $89, plus shipping.

Now, it’s time for all of you readers who are prospective first-time buyers of precharged airguns to do your part. I really want to hear your questions about PCP guns, Don’t worry about embarrassing yourselves because you don’t know everything. Around here, we wait until you’re an old hand and comfortable with us before we start embarrassing you.

91 thoughts on “Some precharged pneumatic basics explained

  1. BB,
    Excellent post! A must read for air gun newbies. I assume you also have a primer like this for springers? Something like this would be a good annual Thanksgiving series to reduce your work load around the holidays and whet appetites before Christmas. You could also include more links to the different versions of each type to help fill Christmas wish lists.

    -Chuck



  2. Good article and very informative. It pulls a lot of information together that you've touched on over the years.

    It may be worth adding a note on service life of the different tanks:

    a) Aluminum 15 years
    b) Carbon Fiber 15 years
    c) Steel 40 years

    G.


  3. I'm a newbie shooting 10m target w/ a Crosman Challenger PCP in my basement. The hand pump is getting tiresome at times. I've tried to do the math but can't quite figure it out. Using the various tanks you mention, how many times should I expect to be able to refill the Challenger?



  4. Thanks for the calculator Kevin. I'm searching the manual and all over the web but still can't find the size of the cylinder for the Challenger PCP.


  5. How or where do you get the carbon fiber tanks filled? I'm newbie and have a Disco w/hand pump, it would be nice not to have to pump but since I dont shoot a lot the hand pump works fine. If I shot more I would like to have a better way. But it seems too expensive to take the next step. HPA Compressors are pretty expensive.


  6. Anonymous,

    Re: Where to get tanks filled

    Great question! Before anyone buys a tank (especially a carbon fiber that needs filled to 4,500psi) you need to find a place to fill it.

    Local fire station and dive shops are good places to start. Filling to 4,500 psi narrows the field but find out where your local fireman and rescue teams get theirs filled.

    kevin


  7. Morning B.B.,

    A wonderful topic with lots of things for us to think about. I liked the comparison between the hydraulic hoist and DIY jack.

    At some point in this series please address the advantages of Benjamine's Dual Fuel
    capabilities and AirForce's CO2 adapter.

    What a wonderful snow storm–Federal Govt shut down. What more can we ask for?

    WV = whori The iternal question!



  8. Nice post, thanks! I would also like to see a post on regulated vs. non-regulated guns and a discussion on the construction and operation of regulators.
    Thanks again!
    Greg


  9. What a great article. B.B. is the king of analogy.

    WARNING. You and your friends will shoot more after you buy a tank for refilling your pcp's. I started cascading my carbon fiber tanks last summer. Long time between filling now.

    kevin


  10. I've been thinking about a PCP for some time. I'm a volunteer firefighter and have ready access to our SCBA compressor and spare carbon fiber tanks. Maybe it's time to put the springers and pumpers on the back shelf. For those looking to fill their tanks, consider joining your local volunteer fire dept.!! We're always looking for help.
    Greg


  11. Kevin,
    Thanks for the fill calc site. I was all excited about calculating how many fills I should get for my Marauder but can't find it's capacity. I scanned the owner's manual a couple times online and reviewed BB's 5 part blog on it but didn't see anything. Anybody know off the top of your head?
    -Chuck


  12. My Benjamin hand pump has failed after less than one month of use. It has the typical problem that others have reported; the handle is difficult to pull up, feels like you're drawing a vacuum. I could send it back under warranty, but I am thinking that the replacement will not fair any better, so I am better off fixing it myself. Last night I partially disassembled the pump, and cleaned the inside of the base and checked the final check valve. The o-ring is fine and there wasn't much residue. I reassembled and the pump still doesn't work properly. I guess I'll have to break it down farther. I saw some internal photos on the yellow as a guide.





  13. BB,

    Thanks for the article! I had wondered how many shots big bores would get off of one fill. I figured Quackenbush guns probably only got one.

    Pounds per square foot should be pounds per square inch in the following sentence under the Big Bore section.
    "After the second shot, the gun is down to 2,200 pounds per square foot (psi)."

    Anonymous G.

    Thanks for the info on tank service life!

    AR


  14. Great PCP primer B.B.

    I have one question for you?

    how long will it take to fill my AAs410 with the compressor I got at harbor freight to shoot my nail guns? :-)

    seriously…
    Kevin brought up a great point on "cascading" tanks.. I'd like to explain that a little..

    You can get connections for two or three tanks hooked all together. Then you can use the air in one of the tanks that's almost empty with say 2,600 # in it.. to bring the empty gun tank up to that point, then shut off that scuba tank, and open the one with 3,000PSI to top off the gun. That way you keep one tank with higher pressure longer.

    It's also great when you have a gun that takes a lower fill pressure like the disco or USFT. I keep one low pressure tank at the high fill pressure for these guns, then I can just open that tank slowly and fill the gun without risk of overfilling.

    Wacky Wayne, Match Director, Ashland Air Rifle Range


  15. I started with the Air Force PCP's – put longer barrels in the Talon SS's. The 24" barrel and C02 has got to be the best C02 gun out there; 17.5 fpe! I get about 50 on poi shots with air and 600 or so on C02 (12 oz tank).

    The Talon's have big tanks and pumping got old real fast. I got a SCUBA tank – A XS SCUBA Steel one rated at 3500 psi. Nearly all SCUBA shops can fill this to 3500 psi so I get extra fills without the inconvenience of fewer places to fill.

    Then along came the Benjamin Marauder; tuned from the factory for about 2500 psi. I haven't touched the tuning yet and get about 30 on poi shots and shoot the last clip (40 total) by aiming a little higher. Out comes the old pump (less than half the volume and lower psi – why not try). This one isn't so bad. Takes about 100 pumps to refil, but the pumping is easy. The Marauder Pistol should be even easier to hand fill.


  16. DB,

    http://talonairgun.com/forum/ has a post on fixing the Discovery HPA pump. Their search engine should find it for you.

    If you cann't find it let me know and I'll take a look see.

    Mr B.

    PS I'm on my 3rd pump and have been using it since last summer filling my Disco and Talon SS.


  17. Hello BB,
    A lot of good info from you and from the regulars, too. Kevin, thanks for the fill link and cascading idea. Wayne, thanks for the additional detail on using isolation valves for the cascading.

    Can anyone recommend a source for small I.D. high pressure line and fittings, etc, that I can use to make up some fill lines and manifolding so I won't be wasting so much air when I bleed the line? It would be nice if they were reasonably priced, too, LOL.

    Thanks,
    Lloyd


  18. Wayne,

    Have you seen that recent interview with Paul Cray? Very interesting stuff, especially for an FT rookie like me. I mean, not as interesting as the daily wisdom from Wacky Wayne, but interesting enough! I see that he doesn't weigh his pellets. Are you still toying with weighing? Did you get that new scale? If we needed any further proof of your Wackiness, I love that you started weighing pellets before you gave in to the clicking. Holdover rules!

    I also see that Cray has switched to a Steyr. I smell another used, "special" USFT that needs to be in your collection!

    Speaking of holdover, I think you mentioned having a new Nikko 10-50x on the way. What's your angle there? Is this one a mildot?

    -Jan


  19. Speaking of FT, I am seriously looking forward to the warmer weather and all the shooting that comes with it. I'm enjoying the snowstorm of the century here in Baltimore, but at the same time, I'm also developing a raging case of cabin fever and an itchy trigger finger. My un-suppressed Disco in my 9-odd-yard basement just isn't quite an all-day shooting arrangement. I should take Matt & Co.'s advice and grab an IZH-61 (or call TKO!).

    Mr B. and other DC/Baltimore airgunners: have you ever shot a DIFTA match? The first match of 2010 is April 17 I think, nudge-nudge wink-wink. Any interest? And DIFTA is hosting this year's national match in October – hopefully a chance to meet Wayne in person!

    -Jan


  20. B.B.

    I seem to remember some Valentine's Day story contest at PA about one's favorite airgun, but I couldn't find a link. Is there such a thing?

    Matt61


  21. One thing scary about PCP is the 3000 psi reservoir. Can you write an article on how they are designed and tested? There've been incidents where aluminum cylinders used for 10 meter rifles had failed. Considering you're paying over $2000 for a rifle they should make them out of titanium, which is much better in fatigue than aluminum.


  22. B.B.,

    I have a question about dual fuel PCPs, but it might be a question for your next installment.

    If normal pressure for CO2 is about 800 psi, and most PCPs are totally pooped out long before getting that low, how do they manage to shoot decently with the CO2?

    Thanks,
    Lloyd










  23. B.B.,
    I've been told by a couple of PCP distributors that hand pumps are not good to use on PCP's because they introduce moisture (whereas scuba tanks provide clean, dry, air), which will shorten the life of the gun.

    Are some PCP more sensitive to the difference between a hand pump versus a scuba tank in terms are wear? In other words, are there some PCP's for which only a scuba tank should be used?

    Victor


  24. B.B.,
    Regarding Anonomys comment:
    "One thing scary about PCP is the 3000 psi reservoir."…."they should make them out of titanium, which is much better in fatigue than aluminum."

    Yes, if you think about the energy stored in the reservoir, its pretty scary. But you've got at least 20 times that much in the scuba tank, and we all watch myth busters and know what those tanks can do. Where's your sportin' blood!?

    But there's more than one way to skin a cat, and aluminum, carbon steel and steel alloys, and various titanium alloys can all make good reserviors, all at different costs. And like BB was describing the carbon fiber tanks, even though the carbon fiber has tremendous tensile strength, the tank needs the aluminum liner for (among other things) crush and impact strength. Given the limited number of fills a PCP sees, fatigue strength isn't a big issue. Threads, welds, fittings, and mechanical damage are more likely to be the issue. Drop your PCP on a sharp rock and dent the tank…hmmm, might want to send it to the doctor.

    Here's a place to play around with tank strengths.
    http://www.engineersedge.com/calculators/shell_internal_pres_pop.htm

    One thing you'll notice if you go looking for stress values to try in the formula is that there are a lot to choose from. One particular steel alloy might have an allowable stress of 40,000 psi in one temper, and 80,000 psi in another temper. You'll also see that given the small diameters of the PCP reservoirs, a thin wall can still give a big safety factor. A lot of care goes into choosing proper material and design of pressure vessels. I'm sure the manufacturers have done the proper engineering.

    P.S. I just saw BBs comment about upcoming embarrasing PCP moments. Are there some Darwin award candidates?

    Lloyd


  25. Victpr,

    I can't say that I know of any PCPs that are so sensitive that they only use scuba tanks. Many if not most target shooters use pumps because they are easier to travel with. And a fill give 100 or more shots.

    I have heard the warnings about water too, but I don't know how to address them.

    B.B.


  26. B.B.

    For years or at least months I looked at buying the Airforce Talon SS, but didn't because it was a 3000 psi gun and I was worried about how to conveniently refill the tank. Then the Discovery came out and I purchased it right away since it could be filled easily with a hand pump. How much harder will the new Marauder 3000 psi pistol be to fill with a hand pump than the Discovery? Also, how many full Discovery refills could you expect from a scuba tank?

    By the way, how's the 30-30 accuracy experiment going?

    Bub


  27. Bub,

    About 25 pump strokes will be harder than your Discovery pump strokes.

    I have not fired bullet one from my .30-30 yet. Too much work. I just got back from four hours at the airgun range and now I'm writing tomorrow's blog. No time to shoot gunpowder.

    The bad weather hasn't helped, either.

    B.B.


  28. Re Carbon Fiber Tanks

    The thin aluminum liners serve only three purposes:

    1) Provide a shape or form to hoop-wrap the carbon fibers and epoxy resins onto

    2) Provide a homogeneous/non-permeable metallic barrier (seal) to contain the gas (or air for SCBA)

    3) Provide a mettalic neck or metal nozzle for threading a valve

    None of these attributes of the aluminum liner are for "impact". Impact or scuffing is from the outside inward, not vice-versa (see fiberglass comment below).

    The preferred carbon fiber for the best quality tanks is "higher modulus" and tensile strength but, even the average tank will use a T-7 type fiber from Toray or Amoco or Mitsubishi.

    The carbon fibers give toroidal strength for expansion and contraction of the alum liner due to pressure. The carbon fibers have a very low CTE or thermal expansion potential, nearly zero for practical purposes, so the effects of heat or direct sunlight create little or no material movement of the tank. For outside influence of scuffing or impact on the bottle, the carbon fibers are over-wrapped with fiberglass fibers and the same resins. The fiberglass is sacrificial in that, it does not contribute to the actual tank strength in any meaningful way and can be nicked or scraped without damaging the inner carbon wraps or integrity of the tank.

    Bottom-line, once the carbon fiber tank is wrapped and cured, the aluminum liner's only "job" is to keep the gas from seeping though and to hold the valve intact and not leak.

    Brian in Idaho


  29. Brian in Idaho,
    Re Carbon Fiber Tanks
    Thanks for that excellent report! I wish the things weren't so danged expensive. I wonder how the local dive shops would feel about the 4500psi, though. I'll have to ask. Not sure their equipment could even handle it, and filling at a fire station doesn't sound like something they'd want to do for just anybody. The paint ball shops are probably the most feasible option. I'll have to search for one of those when I get back home. There are paint ball items sold around town so they must gas up somewhere. I guess I'm thinking out loud here.
    -Chuck


  30. Chuck,

    I remember hearing some time back that there are more certified divers per capita in Colorado than anywhere else in the lower 48. My wife and I are certified divers.

    Not hard to imagine that we have an abundance of diveshops. When I was looking for a place to fill an 88 CUBIC FOOT carbon fiber tank to 4,500 psi I could only find 2 dive shops that had a compressor that could do it. When you said 88 cubic foot to the paintball shops it short circuited them. They're apparently used to filling small pony/pigmee tanks. They dept saying, "you mean cubic inch don't you?" LOL.

    kevin


  31. A little off topic.

    We struggled with Christmas present ideas for B.B. I think the airgun related stuff was appreciated but still kinda seems like buying a vacuum cleaner for the wife. Here's your present now get back to work.

    I'm thinking this years should be something that gets him away from the grind.

    I think he likes RC Helicopters. My idea for his 2010 Christmas present is in this same vein. What do your think:

    http://www.wimp.com/rcjet/

    kevin


  32. Chuck

    You are welcome. Also look on-line for the Scott brand of fiberglass wrapped SCBA tanks. They were heavier than the carbon fiber tanks but also lots less $$. As to the 4000 + psi fill stations, my guess is that about 1/3 of all major SCBA fill stations could handle that.

    The problem with P-Ball shops is usually volume (time to fill) versus 3k PSI + pressures. The P-Ball guys are used to the small tanks.

    Brian in Idaho


  33. I fall in love too easy..

    It's happened again with a Marlin 1894 Cowboy Carbine in .45 long colt.

    It's a remake of the original 1894 with the octagon barrel.

    In the carbine, the pistol rounds shoot like a .223 as far as recoil goes, but really mess up a 2×6 at 50 yards!

    I could shoot it all day long, if the ammo were available..

    I've been buying what I can find on Gunbroker, and saving up the empties.. One of our members is retired and likes to reload, so I'll be trading air gun stuff for ammo soon.

    The 30/30 Marlin is a pussycat to shoot too, but the .45 LC is like half the recoil in this heavy barreled carbine.

    I'm loving it!.. now as soon as my burro gets here… I can go gold mining:-)

    Wacky Wayne, MD. Ashland Air Rifle Range


  34. Brian in Idaho,
    Thanks for all the info on the carbon fiber tanks and manufacturing. I am curious. If the aluminum inner tank (could it be called a bladder?)were removed and the outer fiberglass protective jacket were removed, how sturdy or fragile is the carbon fiber wound shell? I've never seen this process and might have the nomeclature wrong.
    Thanks,
    Lloyd


  35. Lloyd,
    Thanks for the link and comment. Fatigue strength is important that is why I believe those aluminum cylinders have a 10 year life. Not so if they were made from stainless steel or titanium which have fatigue limits.


  36. GenghisJan,

    Thank you so very much for your invitation. No I've never shot in a DIFTA match or any other type of match in my life! Seems to me that I've truly been missing out on alot of fun.

    Count me in. Can I use either my Discovery or Talon SS? What do I need to know, as a newbe. My e-mail address is Dropdog2@Aol.com

    You won't be disappointed with a TKO Stage Five Brake. I'm using the 7.5" one for my back yard plinking with HPA. Not totally silent but very very good–neighboors fine, no complaints.

    Do you have TKO's trigger kit? If not order it when you order the muzzle brake. I'm very satisfied with the way it performs.

    Mr B.

    PS Let's hear it for the snow!


  37. Brian in Idaho and Kevin,
    Brian, 1/3 you say can pump 4500? There are actually three dive shops in the Peoria area so according to your calculations one of them can blow 4500psi. Terrific!

    I'd like to witness the carbon fill process sometime. I've casually watched aluminum and steel fills and they are set in larger tanks filled with water and have to be cooled I think in order to top off the tank. I wonder if that is true for CF? Do they submerge them also and if so aren't they excessively buoyant. Do they heat up?

    -Chuck


  38. Lloyd,

    I will take a cue from BB on this one "your question has several answers" etc (ha-ha)

    Obviously, it's a theoretical question because the tank as I have previously described it requires the liner, the fiber and the resins to be a completed tank or pressure vessel.

    Also, carbon fiber strength can be manipulated by the type of winding patterns and directions and many other engineering factors. In fact, this is how the various mfgrs. differentiate themselves in the weight vs. strength category. Weight vs. strength is really the only thing the tank maker can sell, as DOT and other agencies control the specification minimums.

    OK enough hot-air. Carbon fiber is typically as strong as 70ksi steel at one tenth the weight. That does not mean that 1/10th inch of carbon is as strong in all directions or under catastrophic loads as 1 inch of steel. However, I have seen many burst test photos of CF tanks that did not burst until well over 10k psi and even then, there is an acceptable burst profile or shape.

    If your question arises from the concern of safety, all I can say is that the DOT and the ASME pressure vessel guys allow it in lieu of steel or all aluminum tanks.

    Bottom-line, no human effort is ever 100% flawless but… the reputable SCBA tank makers work in pieces per billion failure rates at the pressures you would use. I would be more worried about a BIC lighter or a CAmry Gas Pedal than a carbon fiber tank!

    Brian in Idaho

    Brian in Idaho




  39. Wayne,

    "I could shoot it all day long, if the ammo were available.. "

    One way to make that happen is by learning to reload.

    BTW, the .45 Colt cartridge has taken American Bison with a single shot from a Little Sharps in that caliber.

    B.B.


  40. BB,
    I'm still not getting a PCP urge, or rather I seem to have gotten over it — maybe I'll always be a springer type, more to mess with or something like that must be the attraction:).

    Wayne,
    I'm really jealous. The Marlin 1894 has been on my list a while now, though I was thinking .357M. Just can't justify it, yet:).


  41. BG Farmer,

    I see the problem. You're thinking about potential purchases. Around our house, it goes like this: See it. Like it. Buy it. Thinking isn't supposed to be part of the process! I suspect Wayne also operates under these rules.

    Edith


  42. Edith,

    You got that right! .. and if need be, sell something to make room or money… but, that's the afterthought :-)

    This beauty came from a long ago transaction, where my new friend at the pawnshop was showing off his personal collection in the back room… I talked him out of a Winchester 72 .22lR with a cool peep sight..

    So, just the other day, he calls me and wants to buy it back… Softy that I am, I went down and looked over his shelves..

    Now you have "the rest of the story" .. he be happy, I be happy!

    B.B.

    How did I know you would chime in with that? :-)

    You have been trying to talk me OUT of reloading for sometime now.. I'm glad to hear you FINALLY agree with me! :-) .. I have to get into it one way or the other…

    ..I will be sort of am reloading.. just by trading stuff on hand, for someone to reload for me.. best of both worlds.. more time to be shootin:-)

    Wacky Wayne,


  43. Kevin,first you tell me no chance of being adopted….now I find out what kind of christmas presents you pick….that's just cruel man! Seriously though,on a scale of one to ten,that's a twenty six!!!He made flying it look effortless.Lockheed Martin just tested the first unmanned Blackhawk prototype for the military…and a couple miles from me I could purchase a RC 'copter for the low low price of $5,000!


  44. Some of you asked for it, so here it is– my first experiences with my new .22 Diana 54:

    Out of the factory box: Stock mostly flawless, all screws pretty tight but rear sight wiggles. If you look inside the big screw holes the shine on the wood doesn't go all the way in. The blueing all perfect except for two slight blotches on the cocking lever.

    It takes a LOT of ooomph to pull back the side cocking lever. As B.B. observed in his post on the 48/52, you cannot release it by pushing the release button unless you have pulled it ALL THE WAY back beyond the cocking stage into some sort of spring loaded dead zone. Upon returning the lever, if you happen to pause and draw it back again even a little, say to get a better grip, something strange happens: The rifle won't fire. The rifle is already cocked and loaded, but… trigger is dead. You have to cock it again, ALL the way. Must be some kind of safety mechanism. Like black magic- don't know what could be going on inside this rifle to uncock it so silently and make you have to do it all over again.
    So I learned to pull the lever back all the way in one smooth motion, then unlock and return it completely in one smooth motion. A clue that the cock was unsuccessful: The trigger stays a quarter inch further back in the guard. Here I thought that the anti-recoil sledge just happened to be slid back, and so it is. You can manually push the action forward and a faint click will lock it into place. But if you successfully cock it and return the lever completely in one stroke the action automatically resets to the fire-ready position forward, and the trigger slides forward in the guard again. It takes some getting used to.

    As I learned in Paul's video, it's best for safety reasons to backstop the rifle against your right leg or inner thigh, then trap the lever with your right elbow or inner forearm. You cannot then load a pellet into the breech with your right hand. So I got used to doing it with my left, but this takes a little more dexterity, since the more generous breech opening is on the right side. Still, a left handed feed is not difficult. After a bit you get more efficient.

    The rifle fires with a very sharp and powerful bark that speaks of enormous power, and the sledge slams back to its stop absorbing the recoil. But you feel nothing. Merely the faintest hint of the huge battle of counterbalancing forces going on under your chin.

    To test my new duct seal silent pellet trap, I tried a 16 grain Predator Polymag. Straight through 2.8" of duct seal and stopped just short of the steel backplate.

    If y'all are bored, tell me and I'll stop here. Otherwise, next my first free sight shots and then scope mounting and sighting adventures.

    -AlanL


  45. I'm also new to the PCP world, as I have yet to buy one.
    Could a scuba tank be refilled with a hand pump ?
    Here's my line of tought : in the evening while watching TV I could be pumping away smoothly and taking breaks whenever I'm too tired, that way I'd have a full scuba tank for the next day shooting session, just like I would be loading pellets in the magazine of my future marauder pistol… is it humanely possible ?

    Does someone know if the marauder pistol tank will be removable ?

    Thanks in advance.

    J-F


  46. AlanL
    That's an awful lot of penetration in duct seal. Are you sure it is duct seal??
    The stuff I got from Pyramyd stops pellets a lot better than that.

    twotalon


  47. TwoTalon,

    Yes, duct seal. The Ideal brand. It is stickier and a trifle softer than the Gardner Bender brand. But that first shot with the Polymag was from only six feet away. I really wanted to test heck out of the trap.
    ==========================
    Nobody objected, so on to part 2.

    First impressions, Diana .22 cal 54:

    My first aimed shots, from 10 meters were all domed 14.3 Grain JSB Diabolo Exacts. First one Low and left. Next one high and left. Third one low and left. Ventured a few windage clicks. Still left. A few more clicks. Still left. No matter what I did, always left, and every shot high or low with a 3" vertical spread, but finally starting to edge the center.

    Rifle getting heavier with every shot. Left arm starting to tremble. Forget the artillery hold. Damn thing so heavy the strain banishes all thoughts of a light touch. Dreams of a bipod bubbling ever more urgently to the forefront of my thoughts. Now everything trembling. Trifocals starting to slip down my sweaty nose. Silent trap now in imminent danger of looking like B.B.'s, but after only a few dozen shots not a few dozen thousand. Air Venturi Bronco in the closet beckons. But no. Persevere! A few more shots. All over the place. The heck with this open sight business. Time for the Leapers!

    -AlanL


  48. AlanL,

    Heavy. Remember I said heavy.

    Are you resting your support arm on your hip or ribcage? In my offhand shooting of the 54 I really had to thrust my hip out toward the target to create a solid foundation for my support hand.

    Test the support point for the gun. In my hands I had to support the rifle well in front of the trigger guard since I had a heavy scope. Find the balance point so you're not fighting the weight.

    The alternative is to bench the gun which is what I would do at this point. Get the sights or scope adjusted and make sure you're on before beating yourself up over the hold and pellets.

    You'll quickly learn what is all the way cocked and what is almost cocked so the gun can be fired.

    Continue the story please. You're helping me relive my 54 experience.

    kevin



  49. .22 Diana 54, part 3:

    Mounting the UTG 460 base was a piece of cake. Carefully tighten but not overtighten the three dovetail clamping screws. Now for the low Weaver rings. Loosen screws more than you think in order to slide them over the picatinny steps. But now a mistake: I only hand tightened the dovetail clamping screws on the side of the lower ring halves and proceeded to gently lay the Leapers 3-12×44 SWAT scope in the lower halves. Went on to mount the top halves, and only started the hold down screws. Now adjusted axially for eye relief and reticle plumbness. Now on to snug down the eight hold down screws, observing carefully a very gentle crossover pattern until all evenly tight with no danger of crushing the scope. Now I discovered that if you attach the supplied 2" sunshade to the objective lens end (a must in sunny Miami) the rear sight will prevent the lens cap from closing. (This with the LOW Weaver rings of course.) So now I got innovative: I disassembled the rear sight and reinstalled it backward. This keeps the little screw holes filled and keeps the sight with the rifle. Diana put a generous coat of oil between the interface of the rear sight and barrel.

    Now to B.B.'s instructions. Two dots 2.5" apart vertically, from ten feet away. Shoot the high one and get your horizontal adjusted in. Again everything to the left. Unlike Tom, 3 shots didn't do it. More like 10! Now back to 10 meters. All of a sudden an ugly rattling and a loose scope. Uh oh, I broke the damn thing… no, wait: The mistake I made earlier: The side clamping screws of the rings had come loose! Tighten heck out of them and start over. No movement at all now. Consistently 1.5" low at 10 meters and centered. Nice!

    But Man is this rifle H E A V Y!! By the time I added the UTG mount and scope with 2" sunshade I needed a crane. Now I was resting my left elbow on a sawhorse. A bloody miracle I got the scope sighted in. Even rested my left arm trembles. You have to be IN SHAPE to shoot a Diana 54. I'm not. Too bad. This rifle is not for wimps. This weekend I'll pretend like I'm not and go for 25 meters.

    More then.

    -AlanL


  50. AlanL,

    I love the details, but I have to agree with twotalon – that sounds like excessive penetration and something might not be right. I can't remember the brand I saw at Lowes and Home Depot, but I felt it was too light to do the job.

    A .22 Polymag (or anything for that matter) shot at my trap from 1 foot with my 16 ft lb gun results in the pellet only penetrating about the depth of the pellet plus about 3/8" into the duct seal. The Polymag actually penetrates less than pellets like the FTS due to the expansion. My duct seal brand is Iberville, which I belive BB has as we bought it from the same source.

    I know that your 54 is much more powerful than my gun, but not to that degree (that would be about 45 or 50 ft lbs in my trap). Be careful, as when you stack pellets you could have a problem. When I stack several they end up about an inch into my trap. I know that you said it is backed with steel, but the loads could start to tear it apart.

    Alan in MI


  51. Alan in MI:

    Unfortunately by now I've shot at least 50 pellets into the trap, so I can't pick out that Polymag one. But I can tell you that my JSB dome heads are consistently penetrating not less than 1.5 inches from 10 meters. I'd even venture to say 1.75". The duct seal is very fresh though. Quite soft. Kneadable with effort. But I made SURE I was buying duct seal and not plumber's putty. Do you think the rifle is shooting too powerfully somehow? But I'm not too worried. I made a half inch layer of duct seal in the back of the trap, then laid the steel plate onto that (I believe it's 3/16" thick) then packed a double layer of pugs over that, and rolled it evenly flat with a short piece of 1.5" dia PVC pipe. I estimate the layer of duct seal in front of the steel at 3.5". I really think I could hit that thing with a .22 long rimfire point blank and stop it cold.

    -AlanL


  52. AlanL,

    Those numbers sound more reasonable – maybe the really deep shots were from a slight detonation or stong dieseling from the new gun?

    I think there is definately a difference in our duct seal though – there is no way I could roll mine out flat with a piece of pipe, no matter how short. I have to use a hammer swung with force to move mine around much.

    My trap is similar in construction, but without the duct seal behind the steel plate (I built it for my eventual purchase of a Marauder). I think mine could also stop a 22LR, but not more than once in the same spot. Thousands of shots is a lot of energy to absorb. Just keep checking it.

    Enjoy, and happy shooting!

    Alan in MI


  53. Well, my guesstimates were off. I just took a piece of wire and inserted it into some of the holes in the duct seal until I felt the pellet. I'm only getting 1.25" penetration. A trifle more if you count the length of the pellet. But the Polymag went in deeper I'm sure.

    The rifle does make an almighty crack when it fires. But I cannot believe my .22 dome heads are going supersonic. No way. I have no crony, but that would way exceed the specs of the rifle, and I'm at sea level. Which reminds me of something I've been meaning to ask Kevin:

    Up in Colorado you are at not less than 5000 feet of altitude. The air's a lot less dense that high up. Does this affect the velocity of your spring piston rifles at all? I would imagine that the piston achieves much less compression pressure for the spring force exerted. On the other hand, the pellet flies through the air with less resistance. What is the net effect then?

    -AlanL


  54. BB,

    I have some interesting data for you on the pellet seating. If you recall, I posted some Chrony results on seated vs. unseated FTS pellets at about 16 ft lbs.

    This involves 15.8 grain JSBs, which my gun does not seem to like much (they do not group well at all). A while ago I sought to find out why, and when I chronyed them, I found I was averaging only about 608 fps, for just under 13 ft lbs when the better pellets were yielding almost 16 ft lbs. So I tried flaring the skirts a few thousands with the beeman pell seat ball end, and I picked up 71 fps, making it the strongest pellet in my tuned Quest 800 (by a small amount) – unfortunately they still did not group well.

    I had my Chrony out for other reasons this weekend, so I ran a test to see if the pellet seating negated the effect of flaring – I figured that it would, but it did not!

    Here is a simple table to let you see the results:

    Normal Pellet:
    Flush , Seated
    607fps , 555 fps
    12.9 ft lbs , 10.8 ft lbs

    Flared Skirt:
    Flush , Seated
    680 fps , 592 fps
    16.2 ft lbs , 12.3 ft lbs

    I expected both normal and flared seated pellets to be about the same, but they clearly are not.

    I am not sure what to make of this (in truth, I make nothing of it really, as it does not affect what I do), but I do find it interesting. I have to believe that the normal pellets would be seated the same as the flared pellets when seated 5mm deep into the barrel, so something else clearly must be going on. At any rate, I just thought I would pass it along and this is the first chance I had.

    Thanks again for all the great blogs, and to all for the wonderful posts. I wish I could contribute more, but am just too busy with work and family . . . .

    Alan in MI


  55. B.B.

    Ive read at different times you mentioning certain springers being lifetime rifles that will last long enough to pass down to future generations (HW's, AirArms TX 200's etc. Are there any PCP's that will have the potential of such longevity?

    PCP's have more parts and are more delicate. What is, or what do you think about the durability of the PCP?


  56. AlanL,

    Yes altitude affects springers. There have been alot of good experiments done. B.B. even did a short test and blogged it on his way to somewhere when the stopped on their way and shot some springers.

    I've only shot my guns at 5,300 feet and about 10,000 feet. What I've noticed when comparing others that shoot at sea level that I trust is that springers lose about 7.5% of their power for every 5,000 feet of elevation gain.

    Some report an increase in harshness in their firing cycle when moving in 5,000 feet increments but I never noticed a differance in the firing cycle after shooting a number of springers at these different elevations.

    The sound is different but that's to be expected.

    I personally think that people are influenced by sound when they say firing cycle. Unscientific but it's my opinion.

    kevin


  57. Bg Farmer,

    I often feel that while good intentions are the motive, blogs on PCP’s often have the opposite effect. They tend to evolve into complexities that can make the intended product seem like way more work than what it would be worth. But take it from someone with an abbreviated attention span at best, they can be as dirt simple as you want, and yes, even without a Chrony.

    I’ve only had four PCP’s, but I already have a good feel for them.

    Here is my official primer:

    First, get a PCP and a hand pump. Forget the tank stuff until you go pro or Crosman finally brings an electric pump to market.

    Next connect the rifle to the pump. The rifle will tell you what to fill it to, mine is stamped 220 bar, but I only go to 200 because I get anxious to shoot and that’s plenty. Once again, I exhibit the focus of a six week old Lab puppy.

    After you sight it in, shoot some more. You do this by aiming and squeezing the trigger. It will go “bang” or if shrouded “ping”.

    Now keep shooting until you see your point of aim start to drop to objectionable level. Then, assuming it is so equipped peak at the gauge. On my Cyclone I stop shooting at 120 bar. I do this as the rifle still has about 4 – 6 good shots left, so if I need it in a hurry there will be no need to pump beforehand. Also keep in mind; you will only need to fill from 120 to 200, never from zero after the first time. Assuming your handle is an accurate anatomical description, this should not be an issue.

    And that’s it. As far as water in the tube, well I know aluminum beer cans seem to last just about forever, even outside, and before that they hold beer without an issue.

    But if you are concerned, the better pumps like the FX include not one but two filters.

    I avoided PCP’s because I felt they were the equivalent of a compound bows, which give me fits compared to a recurve. But the exact opposite is true; Springer’s are the compound bows of the airgun world and PCP are the recurves.

    Volvo




  58. Edith,
    I try to go by the rule my grandparents taught me: spend no more than 1 dollar for every 2 earned, but that seems too extravagant most times:). See it, like it, wait a year after I have money allocated for it to see if I still "need" it, is more my style:).

    Volvo,
    I'm not likely to rest peacefully until a PCP sits in my truck window, am I:)? I'll give your viewpoint some thought (and have before). Did your daughter pass the driving test? I've been worried about you either way:).


  59. Bub

    The number of refills you can expect to get in your Discovery from a scuba tank depends on several factors.

    The size of the tank.

    The air pressure inside the tank. Carbon fiber tanks can hold air at much higher pressure, so even a small tank can hold more air than a much larger, heavier aluminum tank.

    I don't know how many refills you could get from a 4500psi SCBA tank, but I think it would be dozens and dozens.

    Most other PCPs require being charged to higher pressures, so they will drain your tanks faster of course.


  60. One more observation on the Diana 54 that I forgot to make earlier:

    With the 2" sunshade attached to the front of the Leapers scope, it now extends over the breech. This makes it next to impossible to load the pellet left handed as I had been doing. But if you trap the side cocking lever with your right arm, it's also impossible to load with your right hand. So… I started trusting the anti bear trap mechanism. Leaving the lever unsecured and loading from the right is a breeze, but I can't get over the uneasy feeling every time I seat a pellet. The only solutions I see are:

    1) Trust the anti bear trap mechanism.
    2) Use higher rings so I can get in there with the left hand again (maybe).
    3) Take the sunshade off.

    -AlanL


  61. AlanL,
    Keep going!!! If no one has suggested it yet, I suggest you always continue on the current days blog. I'm anxious to hear the rest of the story.

    On your pellet trap, you didn't say how far you were from the target. I assume 10m. I'm amazed you penetrated so deep even that close up. At that rate you'll be pounding the plate with a tight 5 shot group.
    -Chuck



  62. J-F,

    It is impractical to fill a scuba tank from a hand pump, even though it is possible to do so.

    Many years ago I topped off an aluminum 80 tank from 2500 to 3000 with an FX electric compressor, which is a hand pump electrified. It took about 50 minutes of continuous operation to do just that. Imagine 100 sessions with the hand pump to do the same thing, because the compressor operated at 400 percent of the hand pump speed.

    B.B.


  63. AlanL,

    take the sunshade off. I load my 52 by keeping my right arm resting on the cocked lever and loading pellets with my left hand while the rifle's butt is resting on my upper thigh.

    Fred PRoNJ


  64. Alan,

    Thanks for your data on seating pellets. It confirms what my experience has been–that more-powerful pellet guns don't like their pellets to be seated. But the weak ones seem to need it, so there is still some work to be done.

    B.B.


  65. PCP durability,

    Since some 400-year-old PCPs are still in operating condition, I would say they are durable. Spring guns are much newer than that, so it will take a couple centuries for them to catch up.

    B.B.


  66. AlanL,

    I also shoot with my left arm resting on something – a table, my knee (in sitting/field target position) – something. Holding off-hand like you're doing is probably the most difficult position to master. As for that loud crack, the rifle is new and it is probably detonating. As the grease in the compression chamber is used up, it should get a bit quieter and also a bit more accurate – two hundred pellets, at least.

    Keep going – just think of how much larger your bicep and whatever the muscle on top of the rotator cuff is called, will be.

    Fred PRoNJ

    wv: feivench – five inches?



  67. Mike,

    You are not stupid. Everyone has to learn things the first time.

    What you do is this, Scroll down THAT DAY'S blog until you get to the bottom. By "the bottom" I mean the bottom of THAT DAY'S blog–NOT the bottom of the web page.

    That is what you did to get here. You scrolled ALL THE WAY down the page. There are several week's worth of blogs on a page, and even though you did land on the current blog at the top of the page, you went too far down the page before stopping.

    Go back to the current blog via the link I sent you and scroll down the page slowly. Watch for these words at the bottom of that report–posted by B.B. Pelletier @ 5:30 a.m. That is the bottom of that day's blog. To post a comment to that one, click on the word "comments" at the right side of the bottom. It's next to a small envelope and it gives you the current number of comments that have been posted to that blog.

    When you click on the comments, another window will open for you. Scroll to the bottom of that window and post your comment.

    B.B.


  68. Mike

    I am not sure, but I think what might be happening is that when you click on the link for the current blog, when you are scrolling down you are going past the current article to subsequent days. When you go to the current days blog, it will list the previous 6 articles under the current one.

    To post to the current days blog, the easiest way is to carefully scroll down the light blue bar and click on the underlined hyperlink which will be x comments with a little envelope next to it, which will open up the blogger window. You obviously know what to do from there.

    What I like to do sometimes to eliminate boneheaded error on my part, is to click on the top link under "Previous Posts" to the right of the current blog. This will show the current days blog and comments for that day all on one page, that way I don't have to be so careful about my scrolling. Also I can refresh the page to see comments which were posted just recently. I suspect refreshing the blogger window to check new comments messes with the Blogger software's word verification system which results in legitimate posts getting lost, going unposted or requiring multiple attempts. Of course, I am a true computer idiot and that is pure speculation.

    Hope to see you on the current days blog, and keep shooting!


  69. I'm trying to fined out how long I can store my Benjamin Marauder (25) at 3000 psi without causing any internal damage? Bill K.


  70. Bill K.,

    You should store your rifle full of air all the time. It will hold that way for decades. But if you store it empty for even a short time, there will be problems, because small dirt particles will get inside and cause small leaks.

    While 3,000 psi sounds like a lot of pressure, the valve seat is small, and there isn't that much force against it when the reservoir is full.

    So keep your rifle charged all the time — no problem.

    B.B.


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