USAS 12 AEG

[renegadecow]

Having too much time with me being sick and all and practically glued to the net all day (I've coursed through at least 4 episodes of Black Lagoon just for today) I was looking around for a new project gun. And the ugliest, most ungainly weapon in the world had to strike me the most. There are a lot of things in building this gun which makes it very impractical, mainly that it is a shotgun and one that has full-auto. And its also freakin HUGE! Now, I list down my problem areas and hope you guys can help me brain storm.

 

Full-auto buck shot: I only see two ways in going about this and one is having an extremely high rof to simulate having a lot of rounds fly out at once, or rig it so that it shoots more than one bb at time. The problem with two or more bbs leaving one barrel is that only one bb will exhibit hop. The other or the rest will have no hop. This will be a cqb gun anyway so having no hop on some bbs won't matter much, but the problem is how do I get more than one bb to chamber? I can only think of putting a second nub on the sector gear so that the tappet plate will be forced to load 2 rounds per cycle. This would mean that I need to have sub 600rof though or I'm bound to break something.

 

Barrel orientation: It sits higher than on a regular M16 receiver. That said, I'm building it over an M16's lower receiver. The only thing I could muster is to bring the barrel down, making it easier for me not to mention improved ergonomics. But the look of the gun will no doubt dramatically change. Whats easy though is that the outer barrel will just be a long section of steel pipe.

 

Magazine well: I've been looking at some close up shots and it seems to be similar to how old-school guns keep magazines in (Thompson, PPsh) where the mag is not fully enclosed. I'd have to fabricate an entirely new mag well to copy this which will be crazy hard. So how does using the typical M16 mag well design sound? If I equip it with a drum mag, nobody will know anyway.

 

Upper receiver, butt stock, foregrip: Not really much of a problem here. I could make the reciever out of PVC and the butt stock out of wood same as with the foregrip.

 

I'm a bit skeptical on this project myself so I need lots of input and alternatives which could be crucial for even starting this thing.

[Octopus]

For your shot, you could consider a super high rate of fire and a burst limiter like the Airtronics burst unit. According to the FAQ they can cope with some pretty serious upgrades. If you use one of those, a normal spring (As you said its for CQB) and a high voltage battery, then you could have bursts of 3 going out at incredible speed.

[Crimson]

yes use a systema hi speed turbo motor that should help too

[Stealthbomber]

Oddly enough, MDK Marshal suggested a very similar thing recently and I was forced to shoot him down in flames.

 

Anyway...

 

Your biggest problem with shooting more than 1 BB per cycle is the nozzle.

It moves a specific distance and it moves that distance because it's pulled backward and forward by the tappet plate which is, in turn, controlled by the sector gear.

 

To get more than 1 BB into the hop-up at a time you need 2 things:-

1) You need room in the hop-up for them.

2) You need a nozzle that can move backward and forward far enough to accomodate more than 1 BB.

 

These 2 factors are closely related, as you probably realise.

 

If you have a sufficiently sloppy hop-up you can get 2 or 3 BBs to load into a standard AEG. The mag forces them up into the hop-up and they just sort of roll forward into the barrel, one behind the other, before the nozzle returns forward to seal them in.

 

Unfortunately, if you wanted to specifically design a hop-up designed to chamber 3 BBs at once then the nozzle would need to move backwards by at least 4 BB diameters and, probably a little bit more as well. That's an inch!

 

I'm not saying it's not possible but it'll require a lot of playing around and it'll probably produce all sorts of dodgy shots.

 

Also, I dunno if you've ever tried anything similar, if I pump my DE shotty a couple of times, to chamber more than 1 BB, and then shoot it I find that one of the BBs will very often shatter spectacularly.

This might not be the safest thing to have happen.

[MDK_Marshal]

Indeed i did get shot down in flames. It was rather pectacular

 

It MAY be possible to rig something up with a three-barrel affair - some kind of custom cylinder head may be able to do it. Expect to lose a lot of power, though, and have some HORIFIC jams.

 

Basically, fuse the front of a marui shotgun with the gubbins from an AEG. That's the only way I can think of to get more than one round fired at a time - well, the only way that may just possibly perhaps maybe have the faintest chance of working.

[renegadecow]

I think the case of the shattering bbs in multi-pumping cheapo shotties is that the first bb will tend to roll out ahead of the rest. By the time the shot is made, bbs in the back hit the one up front and cause it to break. This is also plausible as their barrels are ######, having leaks everywhere so shooting with a number of bbs in it doesn't mean they all move along leniarly. If I try multi pumping a shottie and shoot it slightly tilted upwards, it works fine. And Maruzen shotties send more than 1 bb out a single barrel without fail, so its really more on making the bbs leave at the same time. Which means I'll need to relocate the hop bucking/chamber forward to have space to keep all chambered bbs together.

As for the TM shottie plus AEG, I'm afraid I'm reluctant on chopping my precious Tactical Launcher, although I do know of a TM M203 being sold for $60... Anyhow, theres also a problem there as the trasfer bar on the TM shottie system also controlls the feeding arm. The movement on this is pretty long and cannot be possibly performed by anything moving in the gearbox. I'd have to somehow rig that arm on a high gear ratio to the gearbox (and externally rigged at that) which would be way out of scale for this project.

I'm inclined with Octopus' suggestion. Super fast 3 round burst for semi using a burst chip and maybe I could have a second chip made that gives small pauses between every 3 rounds as my simulated 600rpm full auto. It'll sound more like a prolonged thunder than one magnificent boom though. But at least the feeding issues here can be solved with conventional methods.

[dismemberd]

the ugliest, most ungainly weapon in the world

<{POST_SNAPBACK}>

[MDK_Marshal]

Renegadecow - I never said my AEG/Shotty hybrid plan was practical, I have no idea how the damned shotty's work - I honestly have no clue as to how they reliably feed all three rounds to separate hop units. But, I guess they do somehow

 

Three round burst could work, but bear in mind you'd probably need at least a 10.8v battery to make it plausible, probably a 12v. and high speed mods and the like... some of the mods are simple, some not so much... IE< polishing the rails in your gearbox is simple, but swiss-cheesing your piston and short stroking your sector gear are nowhere near as easy, and can destroy large amounts of your gearbox if done wrongly.

 

So, if doing the uber-high speed mod, proceed with caution, and do your homework!

 

Slightly unrelated, but this could be a good way to build a replica of the HK G11! You know, the caseless rifle they made...

[doopydoo]

I had a AEG shotty. I took my UTG MP5 apart and I guess I timed the gears wrong, something bad happened and it would shoot 3 bbs on semi every time, without fail. I took it apart and did it right, now it works again. So I just suggest screwing with your gearbox, mess up the timing, something's bound to screw up somewhere, and voila, semi auto shotty.

[MDK_Marshal]

That'd be a good idea, if it weren't for the fact that gear timing is a myth.

 

Let me say that again. Gear timing in the gearbox IS A LOAD OF COBBLERS!

 

The ONLY gear timing you can do is to make sure the sector gear isn;t engaging the tappet plate or piston when you put it together. Why? Well, it won't cycle properley for the first shot if the sector gear is engaged with the piston, and you run a small risk of borking the tappet plate.

 

But that's not gear timing, that's the initial position of the gears.

[blasterbob]

true tis nowt but a myth Im afraid

[doopydoo]

That's what happened... the little notch on the sector gear was in the wrong position with the tappet plate. Try messing that up.

[renegadecow]

yes, but after the first shot it would go back to normal again wouldn't it. I'm guessing that what happened to your mp5 was that the chamber wasn't fit snug enough against the gearbox, leaving a larger space for more than 1 bb to get into. Doing this though would give me a massive air leak.

[doopydoo]

It shot decently far... not as far as normal, but enough for CQB. It would shoot on semi 3 shots always, but on auto it would shoot 3 then the rest of that burst would be normal. If you want a semi only one, that would work.