Hey guys, I was interested in building my first copper gun (ideally it will be pretty small, compact, have a breach-loading or interchangeable barrel system, and probably will shoot marble sized projectiles) because it can be pressurized to higher PSI's than regular PVC. The only thing that I worry ...

Wow, people actually replied to this.

So Im guessing you frequent nerf haven?
Ah, i used to back in the day. I don't actually any more, i'm long past nerfing and essentially have just upgraded my interest to pneumatic spudgun building.

The only nerf gun I ever had was a Lock and Load, which now ...

Just out of curiosity, i was wondering if anybody on these forums ever modified nerf guns? Me and my friends used to do it in about 8th grade, and actually we were able to get them equally as powerful as paintball guns (granted, we made our own foam ammunition since regular nerf darts would blow ...

Ah, true. I think it is still large enough actually, but in the event that it is not i do have multiple ones of the rubber flap sink/tub plugs i mentioned before.

Hmmm, ok. My bumper is dope. I'm using a combination of 4 6" springs, plus a 3" rubber end cap upon which a 2" rubber endcap is going to be glued, to absorb the shock. Not sure what Hooke's constant on these springs are, but they're really good.

Just in case you were interested... I actually found ...

Sure, that's basically the idea i was going for. I was under the impression that a threaded adapter and threaded endcap were actually the cleanout plug and threaded female adapter i was using... oh well. I'm not sure if they make them at 4" but i'll look around. So these threaded adapters and ...

Oh, well then, that explains a few things. That's really unfortunate as well.

Thanks Novacastrian, useful as ever.

Clide, i'm definitely not worried about this valve being compact, however i agree that it does not seem to be a very safe method of securing the pilot chamber. Unfortunately the only ...

Wow, i didn't know that this could possibly have that much recoil actually. I'll definitely be sure to reinforce the back of the gun before i do any sort of test shot, even empty.

I just thought i'd let all of you know i've come up with a pretty sweet mechanism to absorb the recoil of the piston. I ...

Haha thanks for the support, i'll definitely check that gun out.

And yes, it will be an over-under and i definitely will be including much support between the barrel and the chamber, that was clearly going to be necessary with a cannon this size.

hmmm, ok. I think the steel rod is actually smaller than 3/4" but yes the piston in its entirety is has a significant weight. I figured that when the pilot air chamber is released, that since the air escapes more slowly than the air in the regular chamber there would be a small "cushion of air" to ...

By the way, if you want to know how i'm constructing my piston i've attached two plumbing test plugs such as this: http://www.tooled-up.com/artwork/ProdImage/TB28377.jpg to opposite ends of a threaded steel rod (by removing the middle bolt which you can see in the image, and sliding them on to the ...

Eh well, i'm ambitious and bored.

I dont think it should damage its self though. The only way i could see it doing that is by the back of the piston slamming into the endcap of the pilot chamber, and thus that repeated shock causing eventual deterioration and ultimate failure. But i'm going to be ...

Petroleum Jelly? As in vaseline? That stuff is pretty thick, i've used it on some valves in the past and it doesn't move too quickly, and from my experience the seal was inconsistent.

I've bought some plumbing lubricant actually, it seemed to be what i was looking for, but i haven't tried it out ...

... seriously?

Also, i forgot to add this, but i was wondering if some lubrications work better with different kinds of rubber?

Hey, i'm new to these forums but not so new to the world of pneumatic spudguns. I'm currently building by 3rd spudgun, and so far its going to have a 4" by 10' barrel and a chamber maybe twice the size.

However, since i'm looking to maximize power i figured that it would be necessary to build a 4 ...