Ideas wanted: Browning M2 Reciprocating barrel

[Pkekyo-Nor]

I'm in the progress of building a Browning M2HB that will run on HPA.

The machining is fairly simple - just CNC steel and some elbow grease.

 

However, the HPA system is giving me pause. I have little experience with HPA, and no experience designing the actual mechanisms.

The intent is for the weapon to not only shoot 6mm BBs, but also have a reciprocating barrel.

Thus, I was hoping to get ideas on how to achieve the latter from you lot.

 

Thank you for your time.

[Danke]

You would need to make a copy of the real deal. The outer barrel would need to be attached to an inner carrier that you'd cycle back and forth. I'd guess a cam would be the easiset way to do that.

 

Think like a piston on locomotive drive wheel.

[Sallinen]

Escort system to the rescue!

Design wise I think this would be "fairly easy" thing to do on the Escort system.

For example AK engine is just an engine that, when pressurised, cycles back and pulls the bolt along on the way. The bolt could be easily changed for some sort of attachment to pull the barrel a bit and how much it pulls is just a matter of adjustment.

 

I'm sorry that I dont have better images but I hope these help:

This one is the part that pulls the bolt back: http://imageshack.us/photo/my-images/855/dsc04629.jpg/ note the lip.

Heres the whole engine: http://imageshack.us/photo/my-images/18/dsc04634th.jpg/

 

Also:

http://classicairsoft.org/forum/showthread.php?8408-Sun-Project-M16

Here's a nice gif of how the system works.

[Pkekyo-Nor]

So in theory it's simple - manufacture a sleeve that goes over the barrel and attaches to the piston... Right?

What was giving me pause was really that I have no idea how much of a strain I can put on the mechanism.

The idea is to have it capable of 450FPS at a respectable ROF with realistic recoil. I don't know what the weight of the barrel will be yet, however.

 

Allright, the goal is set then. Still, I am somewhat uncertain.

I will be retrofitting a HPA kit for an M60 that is being given to the project for free by a friend that's had it laying around for ages.

Can't for the life of me remember who made the kit though.

 

Will report back here with the brand sometime tonight, in case that changes anything.

[Danke]

At the receiver end picture a box inside a box. The outer box is where you have the charging handle, sights, feed cover etc and that stub of perforated air jacket.

 

The inner one would have the mechbox and feed fixed to it along with the outer and inner barrel. Yould have a cam that you'd drive by bleeding some of the air from the HPA kit. That cam would mover the inner works back and forth to simulate firing. You'd need to do some trial and error to syncronize the motion to the actual firing.

[Stuey]

A user on here called Catman and his mate from the Manx airsoft club made exactly what you're describing - a HPA powered M2 with a reciprocating barrel. They ran it off a scuba cylinder and eventually mounted it on a Land Rover, was awesome. Sadly their build log website is down (it was quite a few years ago now) but I think there might be a thread on here somewhere...

[Pkekyo-Nor]

Apparently, the M60 HPA kit was manufactured by Escort, so I figure it should come together relatively smoothly.

Thanks for sharing your knowledge, and if anyone else has some input I'd love to hear it.

[renegadecow]

Catman, classic Catman. Haven't heard from him for a long time now, but you ought to contact him in any way you can.