The Joys of Being Back- .25 Cal QEV Long Arm

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
thedeathofall
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Sun Jul 25, 2010 11:42 pm

So it has been a while... A long, and somewhat painful while without being able to build. But its summer again here and I am at home again with full access to weapons building tools and a larger bank account due to an actual job. After a day with an old friend who wanted to plink a little, I realized that I needed to make somthing more reliable than what we were using at the time.

This is a simple QEV launcher. 1/4 inch npt valve, with a 33 inch barrel of .25 inch ID brass tubing. I shoot 1/4 inch chrome steel ball bearings and airsoft bbs. An old 3/4 inch npt piece of pipe I found that belonged to an old pipe threader makes the chamber. Simple right? But then I had to make it look purty :roll:

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Yes that is a rail on top, and a M15 A4 Carbine butstock from an old airsoft gun. Ive been having trouble with sighting. This thing shoots extremely high (about a foot high at 45-50 feet), but is really, really, powerful. This packs more punch than my .177 cal single shot pellet rifle. I had a rifle scope on it at one point, but due to the problem with the accuracy, it was unusable.

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"I'm spending time without a gender for tax reasons. It's great if I get hit in the groin, but a total nightmare in the bathroom."

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caz259
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Mon Jul 26, 2010 12:39 am

That is very Sleek :o, does the chamber run along the top of the gun and also into the stock or is it just one? What kind of range are you getting and some damage pictures would be amazing
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jackssmirkingrevenge
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Mon Jul 26, 2010 4:53 am

Looking good, what pressure are you running at? Looks like it will happily take a couple of hundred psi.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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lozz08
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Mon Jul 26, 2010 6:02 am

really nice job, looks like it could take down a rhino! (well, maybe with larger ammo) you could try making a somple hopup by drilling a hole in the top of the barrel and inserting the rubber from the back of a pencil. that would help accuracy a fair bit i would think. seal it with silicon glue from a hobby store because it will give a good seal but be removable for when the rubber runs out.
thedeathofall
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Mon Jul 26, 2010 4:25 pm

Hey guys. First of all Caz, the chamber is actually under the barrel. Its the shorter tube. The stock is not part of the chamber, and does not need to be.

I run it around 110-120 psi only because I dont not have access to any high pressure source. I have been thinking about making a smaller bore pump, but havent gotten around to it.

Lozz, I dont have a problem with accuracy per say, its elevation of the BB that is getting me. It simply shoots really high. Putting backspin on the BB would only increase this problem. As is, the BB is can shoot fairly straight and even for 300+ feet without dropping and at point blank range will go through the tops and bottoms of 4 aluminum cans (pop cans not soup tins).

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Well It hasnt even been 24 hours and I am already messing with this thing.I cut off the barrel and it now resembles a police shotgun. This actuall helped with the accuracy because the last 6 inches of the barrel was bent upward... go figure.

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This is a 1 shot 3 round buckshot group at 25 feet
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And the cans were individual shots from same distance

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"I'm spending time without a gender for tax reasons. It's great if I get hit in the groin, but a total nightmare in the bathroom."

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jackssmirkingrevenge
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Tue Jul 27, 2010 12:24 am

thedeathofall wrote:I run it around 110-120 psi only because I dont not have access to any high pressure source. I have been thinking about making a smaller bore pump, but havent gotten around to it.


Shame because with small bores, pressure really counts for good power.
As is, the BB is can shoot fairly straight and even for 300+ feet without dropping


No gravity in your area then :wink:
hectmarr wrote:You have to make many weapons, because this field is long and short life
thedeathofall
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Tue Jul 27, 2010 2:32 pm

No gravity in your area then
You sure it's just my area? I thought everyone ate breakfast on the ceiling... :roll:
"I'm spending time without a gender for tax reasons. It's great if I get hit in the groin, but a total nightmare in the bathroom."

-Rag


Obsequium parit amicos; veritas parit odium.

-Cicero
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