50 caliber 28 Shot Breach/Muzzleloader QEV Air rifle

[mpmrla]

Homemade totally off the shelf re-purposed muzzleloader. It's being fired with 250 to 300 psi air from a good quality 250 psi stirrup pump or my re-purposed 30# propane tank with pod pop-off protection at 315 psi. The 300 psi air is obtained by piggybacking an R-22 compressor onto a 120 psi shop air compressor. The lowest pressure rated component in the system is the Alpha QEV rated at max 250 psi with a burst pressure of 2 to 3 times that. With a properly rated homemade piston valve the operating pressure could easily be quadrupled. . I use a .495" ball is just large enough to feed through the 1/2" opening in the receiver. The QEV is an Alpha 5UPH4. The trigger is a 1/8" push button vent valve used as a pilot valve. This gun is also a fine arrow launcher and conical bullet muzzle loader. It makes a pretty decent shotgun at 10 to 15 yards with a 184 to 552 grain shot load. i have added a CO2 system and am firing it at 400 psi now. You don't have to use a schrader, foster, quick connect or ball valve on the supply air to the QEV if you use a small orifice in that fitting. The orifice will prevent the supply air from interfering with the venting of the 1/8" vent valve since it slows down the pressure build up to the accumulator tank which allows the vent valve to stay ahead of any pressure buildup on the pilot side of the QEV. This gun also has only three moving parts to keep it simple reliable and easy to build. It is reminiscent of the the Red Ryder gravity fed bb guns. Remember if you add a spring a large portion of the magazine is wasted. Also since you have to wait a couple of seconds for the accumulator to recharge anyway you can use this time to tip the gun and gravity feed a round. Just keeping it simple.

You can see the gun in operation on my youtube channel at

http://www.youtube.com/user/mpmrla?feature=mhee

Here are a few photos and two build drawings of the gun

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[wyz2285]

I loved that video, smooth action! :thumbright:
The chamber looks kind big, make it smaller may look better without significant power lose.
Is the bolt action o-ring sealed? not a big deal if it isn´t but would be really nice to do that.
Congratulations!

[jackssmirkingrevenge]

very nice, what Girandoni would have done if he had a home depot around the corner

[mpmrla]

The air chamber on this gun is only 1-1/4" diameter by 10" long.
It is shrouded with 1-1/2" PVC to give it more comfort against the
cheek when using CO2.

[mpmrla]

The annular space around the bolt is so small I had to sand the bolt down
for a smooth fit and the stainless steel tee has a smooth and consistent diameter throughout. Also the volume of air in the chamber overwhelms
the tiny amount of leakage around the bolt. I actually shot a single shot with
the bolt out and the receiver hole plugged tight and didn't get a noticeable
difference in performance. The tiny amount of air escaping there also helps
to keep the tight fitting bolt clean. I guess this wouldn't work too good if the
gun was using 3000 psig air and only burping out a few cc's of air by hammer valve action.

[Gun Freak]

Sweet! I like the bolt action. You should add a spring so you don't have to tilt the gun back to load it, that way you could fire a lot more rapidly!

[Lockednloaded]

Cool loading mech, with some modification and rotation you could easily make it lever action with an under barrel mag tube

[mark.f]

Cool loading mechanism, like others have said. I don't think you need to add a spring since, as you said, it takes some time to fill the chamber anyway (could be solved with a 3-way valve), and tipping the gun up isn't that big of a step.

Also, it looks a little blue in the video... what color is it?

[mpmrla]

This one will be flat black when all the painting is complete.

[mpmrla]

A spring in the magazine just adds more difficulty in constructing the gun
since you would need a heavy spring to push the 3/4 lb of lead that 28 balls
makes up. You would also need a very long spring and several inches longer
magazine tube. I am trying to make it as simple and reliable as possible.
You need about 2 to 3 seconds for the chamber to charge up to 300 psig
anyway so why not use that delay to tip your gun up and re-aim. Remember
the old gravity feed bb guns.

[Gippeto]

A bang up job (that means GOOD where I come from ) IMO. 8) Rate of fire is fine too.

A 20oz co2 tank and palmers reg would give good portability ....that's a hint....I've never been accused of being subtle.

I think you're well prepared for the zombie apocalypse everyone is predicting. :thumbup:

[mpmrla]

Yes! Yess!
when i am not video recording or testing i use the 20oz co2 and high pressure stabilizer set at 400 psig for shooting. The setup in my 1st pic above.

[Gippeto]

Well...face palm for me then.

[Brian the brain]

Seen it on youtube before.I asked you about showing it on SF.
You said you already had.

Must have missed the earlier version
Anyway...as I commented on youtube:
I love this thing!

[mpmrla]

I made a few corrections to the parts list for this cannon