SpudFiles

Alright, here's the first gun I've made in quite a long while. It's given me lots of trouble and is probably the most work I've put into any size of launcher. Instead of just cutting pipe and cementing it together correctly, this thing took lots of hacking and test firing and adjusting and test firing and smashing my thumbnail and test firing and scrapping lots of parts and then some more test firing.

<a href="http://www.spudfiles.com/forums/need-so ... html">This topic</a> didn't end up mattering at all because I ended up ditching a blow forward or blowback bolt, after the blow forward didn't work, the blowback didn't work, then the blow forward worked but broke itself. <a href="http://www.spudfiles.com/forums/qev-dif ... html">This topic</a> was helpful, however, so thanks to everyone who gave some advice. The blow forward bolt broke itself but the gun still works as semi auto with no moving parts, just an airtight hopper.

OK, specs:
1/2" x 7" galvanized steel chamber
1/4" QEV piloted by modified blowgun
9/32" brakeline barrel, 30" long

So basically this is meant to be a gun that I can shoot my friends with when we have airsoft fights. I have a propane tank strapped on the gun for a power source and to use as a stock. I also have a regulator, which is absolutely necessary for any homemade launcher which is intended to be shot at people. I can adjust the pressure from 0-120 psi, 120 psi being able to shoot through both sides of a can and 35-40 psi as the normal running pressure.

To shoot, you unscrew the 1/2" plug in the hopper, pour in some BBs, screw it back on, and open the ball valve which is right next to the propane tank. This runs propane to the regulator. Then you set the regulator's pressure. After that you just open the other 1/4" ball valve, close it, shoot, open, close, shoot, etc. Sort of semi auto. The gun can also shoot as a normal semi, but that wastes huge amounts of propane out the pilot valve, so I prefer not to. Also, opening and closing the 1/4" ball valve every shot makes the gun less "cheap" to use against my friends (who use my only actual airsoft guns: 2 spring pistols).

I chose not to paint it because I like the way it looks now. Don't criticize that aspect of the gun. Also don't criticize the slight angle on the propane tank. I don't care. This gun was made for functionality, not aesthetics.

I spent loads of time on this thing. Assembly of the launcher was easy, but putting together the blowgun handle, the front grip, the barrel, the hopper, the T with hopup/detent, and everything else took hours and hours.

EDIT: I messed around with it and did what Poland_Spud suggested, and now it feels pretty much the same but looks a bit cleaner.

nice i think i found out what u meant are u gonna up the presure for testing or no?

I've managed to get a maximum pressure of 120 psi from the propane tank. There's no reason to up the pressure past 40 psi because I don't want to shoot holes in skin.

Nice work. definently not a bad gun, especially since you got it working with semi auto (I've tried doing it before but mine was crap)
The only suggestion i will make is parhaps you could fit it all in a large peice of pipe, so it doesnt look so... ghetto.
apart from that, awesome work!

If you think it looks ghetto now, you should have seen it before I attached the front grip and clamped everything together. It doesn't look too great but having the pipes and hoses running around all over it makes it look complicated or something. I like it.
It is also very comfortable to hold and shoot, regardless of what it looks like.

I like but seeing as its chief merit appears to be functionality, a video would be nice

I would love to have provided videos for all of the strafers and launchers I've made, but my mom's camera doesn't take videos. Also a video of this wouldn't be all that impressive, it's just a low pressure, low velocity airsoft gun.

Looks a little ghetto but that makes it look complicated it kinda looks like a hybrid. About the bent propane tank i think it looks better that way because it acts a bit like a stock.

first off all, there are things I like about this launcher and some I don't

I like that fact that it's fully self contained - you used propane which is a really good idea

I don't like that blow forward part of the gun - as I suggested earlier (and as you realized yourself) these things are real PITA to build...

now it seems that you can either build a proper T for loading or add an air cylinder to cycle ammo... the latter might seem to be more difficult but in the end you'll have simpler and more reliable construction

I think that some 3 way valve (even a slide valve would be ok) would improve the design a lot... while these things seem expensive at first they can be used in your future projects.. so consider that

also overall aesthetics would improve if you manage to attach all the parts via threaded fittings... you know, so that malleable iron pipes and fittings would hold everything together.... that would require some work but (no offence) now all the parts seem to be barely holding together


sorry if you find my post depressing...I can see that you must have spent hours working on this but I wanted to write something constructive, not just another 'nice I like it' post...

Poland, thanks for the post. Yes, it may have been a little depressing but it's not too bad, and certainly helpful.
I don't know if you missed this part, but there is no blow forward in the gun right now. There are no moving parts at all. The loading system is just a block of HDPE drilled out to make a T, with the hopper coming in the top and a toothbrush bristle on the barrel and valve side of the "up" tube of the T. These act as a ball detent; I can aim straight up or straight down and the BB won't roll out, but the bristle can easily bend out of the way when pressure is applied.
Since I don't have an "actual" feeding system, it shoots double feeds probably a quarter of the time, but that doesn't bother too much.
Overall aesthetics are the way they are because the only things I bought for this project were hopper parts and teflon tape. The gun itself looks more like a QEV BB gun without the hose clamps, but then the propane tank and blowgun handle just dangle around on air hoses. Strapping everything together was the only way to fix that aspect.
However, I may still use some larger diameter ABS pipe to sleeve parts of the gun so it doesn't look as exposed. I'll make sure to see about that today.

uhmm sorry I though that you had a blow forward on this gun, it broke down and either you didn't remove it and works as a simple T with an airtight hopper or that you removed blowforward bolt and slightly modified the loading mech to work as a simple T

is it possible to join all the main parts (including the propane tank) together via threaded fittings ?? since you need to reg propane down you could use threaded fittings just in order to attach the tank.. they can really take a lot of stress...

I might be able to attach the propane tank with threaded fittings but I'm not sure.
Just checked, and yes, I could. It would be very easy to do but unfortunately I wouldn't be able to use it as a stock if I did that. I could simply get rid of all the hose and attach 2 street elbows instead. But that would mean the propane tank would be facing the other way and I wouldn't be able to use it as a stock.
I'll see about it anyway. I'm sure I could make a simple PVC stock which could be attached solidly to the street elbows. I think I'm probably going to keep it as is for at least another day or two.

How much shots can you get from your gun at airsoft velocity ?

nice. If you acquired a 3 way push button valve, it would be a true semi auto, and it would be much more ergonomic.

here