SpudFiles

I know I'll get a lot of hootin' from Jack and others about how I should go PCP if I want to make a homemade airgun, (after all, that was what the first airguns operated off, right?), but I like multi-pump pneumatic rifles because of the variability. Not too great for accuracy, but they're fun, easy to buy/make, and simple.

Anyways, IF I were to make one, this is how I'd do it...

1.) The barrel would probably be steel tubing, of 0.32 caliber or so. I find 0.32 caliber a convenient size because I can get #00 pellets in buckets that size, copper coated...

2.) The pump is easy. The pump tube will be copper, and the actual piston seal will be a test plug, because they're easy to get and seal great. The pumping handle will probably be a piece of plastic pipe that is large enough to fit around the copper tube when cut in half to make a good forearm. The screw that connects the pumping rod to the forearm will stick out the other side, but that can be used to attach a sling or whatnot.

3.) The valve will, of course, be a hammer valve. I have the plans in my head, and the design I have will seal the air out of the action and direct it all into the barrel.

4.) The bolt will only load the pellet. Cocking of the hammer will probably be accomplished with a separate charging lever. It's too tedious to make the bolt cock the hammer.

5.) The bolt will probably be dowel rod, because it's easy to work and will seal reasonably well when an O-ring is added.

Any suggestions? I probably won't use this for any target shooting, but rather for hi-power plinking. If I can find a cheap 0.45 cal muzzle-loader barrel, however...

Sound's like a sound design...I think its good that you build you gun with the ammo in mind. It sucks when you build a nice gun and then you realize, "Crap now what can I shoot out of it."
How much pressure you plan on putting through it?

markfh11q wrote:I know I'll get a lot of hootin' from Jack and others about how I should go PCP if I want to make a homemade airgun, (after all, that was what the first airguns operated off, right?), but I like multi-pump pneumatic rifles because of the variability. Not too great for accuracy, but they're fun, easy to buy/make, and simple.

Actually, if you ask most airgunners to describe their perfect rifle, most will tell you it will be a single stroke pneumatic, combining the recoilless quiet action of a PCP with the portability and self-contained action of a springer so yeah, not great on the power front but otherwise, go for it.

Jared wrote: How much pressure you plan on putting through it?

That really depends. Like I said, the pressure will be variable because of using different pumps, so I will really only be limited by my selection of materials for the pump cylinder and reservoir. The pump cylinder I can make of type K copper, and the reservoir I can make of steel, so I'd say a sound limit would be 500 PSIG, (I can tell you how many pumps that will be once I finalize how long the pump cylinder will be, and what diameter). Another limiting factor is how small in diameter the pump cylinder is. I could have a pump cylinder with one square inch surface area, but only be able to get around 100 or so PSI before my handle snaps in half. If I make the pump's piston surface area small enough, I can easily get up to 500+ PSIG with a suitable mechanical advantage factored in, just in a larger number of pumps.

EDIT: Jack, like a described above, I can make the gun a single-stroke pneumatic by making a larger pump cylinder. This will increase cocking effort and decrease muzzle velocity, but the consistency will be much better.

I love our single-stroke match rifles for ROTC. I bought a cheaper entry-level variant, (Powerline 953), but I've modified it enough to get it nearing competition level.

The Parker-Hale Dragon was a single stroke pneumatic that could develop the full UK-limit 12 ft/lbs of muzzle energy, so you're not neccesarily looking at very low power.