SpudFiles

Quick exhaust valve BB gun

This gun has some serious damage for its size (chamber wise). With 180PSI I can get a BB stuck all the way in my wooden garage door and wit only 140PSI BBs will go through thick tin (picture).

I got the barrel attatched by wrapping it in electricians tape and then wedging it in between the QEV exhaust and the lip inside the reducing coupling.
Specs.
Barrel: Car fuel line (6.something mm ID)
Chamber: 15mm and 28mm copper pipe.
Valve: 12mm QEV IIRC
Exhaust/trigger: Brass blowgun

The main gun:


The fill/trigger setup:


Damage to a tin biscuit lid from about 6 feet away:

Sorry for the crappy last pic. DC cam died on me as i was going for a less "shiny" picture.

Comments/suggestions welcome.

look nice but ware is the damage to the tin can? and that blow gun is sweet.

The damage picture is sorted, sorry about that.

The blowgun was picked up by my dad from a "Carboot sale" for about £0.20 ($0.40 to you Americans) and it looks/feels WAY better than the standard ones.

I wish I had a blowgun like that...
What size BBs are you shooting?

I was thinking about making one of these, now i think i will! Very nice job, by the size of the barrel, damage id say that he is shooting .177 bb's, correct me if im wrong.

Yeah they are the standard 6mm BBs I do believe. I just bought a lot of 4k from eBay for $20. Pricey I know, but hey, the only price I could get decent, seamless ones for.

why not buy them of an airsoft site? i got 5000 .25g seamless for $15 and it was one of the more expensive sites (i was saving money on shipping)

thats nice i like full metal pneumatics. when i get enough money i will make one.

A smaller pilot volume and larger chamber would give a noticeable boost to performance, which you will need to discourage people from sniggering at your two-tone socks

What do you think of changing the copper pilot area for a threaded tee and a check valve?

It would automate the ballvalves duty and reduce the pilot volume.

jackssmirkingrevenge wrote:...which you will need to discourage people from sniggering at your two-tone socks

I concur - mastery of the crop function is scarce today.

@ IM: Haven't seen you around for yonks! How's it going with you these days?

For plastic BBs, that's a lot of mess. I guess that lid's in the region of .5 mm thick?
I have difficulty getting high density pointed ammo through more than about 1 or 1.5 mm steel (but there is a square law involved...), so I'm at least partly stunned at what a plastic BB can do to .5mm.

Kudos to you.

Well, I'm realy pleased with the opening times with this gun, and it doesn't matter as QEv's have NO backwards flow of air, so even if the pilot was 100cm2, it would still be just as powerful, just make 2 wooshing noises.

I don't want a bigger chamber, as it would be wasted. As is, I believe my chamber is still bigger than needed, and increasing the chamber would mean it would take WAY more pumps to get to 250PSI with my shock pump.

Joanna: I never left, just didn't bother posting realy. I've been keeping a keen eye on all the guns posted through out the year and all so i've been lurking. I too was stunned to see the damage done by the BBs. They do a huge deal of damage close range, but because of their feather light materials, accurace is lacking with this at distances over 10m.

joannaardway wrote:For plastic BBs, that's a lot of mess. I guess that lid's in the region of .5 mm thick?
I have difficulty getting high density pointed ammo through more than about 1 or 1.5 mm steel (but there is a square law involved...), so I'm at least partly stunned at what a plastic BB can do to .5mm

Don't forget that it's a biscuit tin, not rolled homogenous armour, metal quality is as important a factor as thickness when it comes to resisting penetration.