9mm bolt carrier that doesn't require a buffer tube?

[keyhole]

Title says it all. I'm looking for a 9mm upper that doesn't require a buffer tube (receiver extension). In other words, a bolt carrier that's cut in half and operates off of some sort of spring that's held completely within the upper.

My google-fu is weak on this one.

[Mad Machinist]

Your Google Fu is not weak....such a critter dosen't currently exist. DI guns with out buffers have been done......but unfortunately 9mm does not lend itself to DI (I built one and have experimented with it). The problem with a bufferless blowback 9 is retaining the mass of the bolt........unless you can do that....then you run a serious risk of out of battery discharge. I KNOW how to build one but the weight will have to be shifted forwrad of the chamber encircling the barrel.....and the reciprocating mass under the handguard would peobably make shooting it like trying to hold on to a pissed off squirrel. A far simplier solution would be a custom upper and lower designed to accomodate whatever AR parts you want to use. Increasing the diameter of the upper receiver allows the mass of the bolt to be increased to the point of practicality.

[keyhole]

After posting this, I came across RRA's LAR-PDS. It's exactly what I'm looking for, but only comes in 223. I've read comments from people who work at RRA, and they say it is not compatible with a standard lower because it causes damage to it. But I'm wondering, if it's converted to blowback 9mm, maybe the weaker round will not cause damage?

[Mad Machinist]

Weaker round....but significantly higher mass required for the bolt and significantly more stress on the action because of the required reciprocating mass.......unless you have a locked breach you MUST have the higher mass of the 9mm blowback bolt and buffer......and 9mm just dosen't run worth a damn in a DI system.....I built one and It just isn't commercially viable....and I build pistol cal AR's for a living......I've built in 45 ACP, 10mm (both DI) 7.62 x 25 Tok (DI) 40 S&W (DI and blowback) and 9mm (DI and Blowback).
The requirement for the mass of the bolt makes it very difficult to build what you are looking for....can it be done....yes....will it be a satisfactory result.....never know till it is done......but my guess would be a muzzle heavy jumpy critter that might have reliability issues. If you want a folding stock 9....AK is a better platform.

[MarkG]

....and I build pistol cal AR's for a living......

Really? I think there is a requirement that your signature block include the name of your company and such.


I've built in 45 ACP, 10mm (both DI) 7.62 x 25 Tok (DI) 40 S&W (DI and blowback) and 9mm (DI and Blowback).

Video and pictures are mandatory, or you know... they don't exist.

[Mad Machinist]

I was waiting review all the rules and make sure mentioning things like that weren't prohibited.......
I focus on DI 45 but do a significant ammount of blowback work in 9mm and 40 S&W......shoot me an email to rudyk@maconarmory.com and I'll be happy to help you anyway I can......and I'll try and get some videos up soon....hows this for a teaser....

https://www.youtube.com/watch?v=1AyOPATXW7Y

This is a DI45 upper and we can run it on a standard lower with adaptor, CNC AR45 and Bazooka Brothers dedicated greasegun lowers, GWACS Cav Arms lower with Hahn magwell adaptor and greasegun mags, and the QuarterCircle (formerly DDLES) large frame glock mag lowers. I have another option in preproduction....but it'll just have to wait for the formal unveiling....still have to finalize and beta test it.

Dug up the video of the original DI 45 prototype I did years ago.....
http://i368.photobucket.com/albums/oo121/MadMachinist/th_MOV03327.mp4 (http://i368.photobucket.com/albums/oo121/MadMachinist/MOV03327.mp4)