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Mr.Poopypants
10-14-2009, 12:15 PM
Assuming someone wanted to use an exceptionally short buffer tube, what's the shortest length that would still allow the rifle to cycle properly? I'm not talking about buffer tubes currently available, but rather trying to figure out how short of a length one could craft in order to make it work properly?

I know that 9mm ARs can use shorter buffer tubes -- in fact, if I am not mistaken, a 9mm AR doesn't need a buffer tube. I also know that .22 conversion ARs don't need a buffer tube, as the recoil mechanism is housed in the bolt itself.

I also know that .223/5.56 ARs can use different length buffer tubes, buffers and springs, but I don't know if what is currently available is based on the need for a stock and subsequently using the space in the stock, or if stock or not, the usual length buffer tube is absolutely required.

I presume that the factors one would have to take into effect are: the distance the bolt must be able to travel in order to eject a spent casing and load a new round, and the space required to have some sort of buffing mechanism to reduce the recoil of the rifle.

Anyone have any idea of what is possible using a standard BCG?

technique
10-14-2009, 12:26 PM
I don't know...for a centerfire you still have to maintain the 30inOAL (26in with rimfire)

I can't go any shorter personally (well actually I can 26in is fed law for me)
But my AR with 14.5 barrel perm welded FH = 16.1in, the OAL of my AR from buffer tube to flash hider is 30 1/4in....

It would be hard to cut 4 in off the buffer area....Gunsmoke Ent. makes a tiny buffer system for pistols you might be able to modify and put a stock on?

munkeeboi
10-14-2009, 12:31 PM
9mm need the buffer tube.

Mr.Poopypants
10-14-2009, 12:43 PM
I don't know...for a centerfire you still have to maintain the 30inOAL (26in with rimfire)

I can't go any shorter personally (well actually I can 26in is fed law for me)
But my AR with 14.5 barrel perm welded FH = 16.1in, the OAL of my AR from buffer tube to flash hider is 30 1/4in....

It would be hard to cut 4 in off the buffer area....Gunsmoke Ent. makes a tiny buffer system for pistols you might be able to modify and put a stock on?

Thanks for the info. I'm using it to play around with an idea of making a bullpup conversion with a long barrel. I don't have an AR on hand to measure the length of a bare upper and lower, so I can't say if a 20" barrel and a upper/lower with no stock would hit 30", but I figure that if it's a couple inches short, the needed inches could be used to house a short buffer system. Just trying to figure out how short a buffer system needs to be in order to allow it to cycle.

Mr.Poopypants
10-14-2009, 12:49 PM
Ok - thanks to Technique for the Gunsmoke Ent. info. They sell a 4" buffer system. Looks to me like the receiver assembly is roughly 8". Combined with the buffer, and an 18" barrel, the OAL would be 30".

Thanks!

munkeeboi
10-14-2009, 1:20 PM
but then, you would have a rifle with no stock (unless you chopped up a regular size stock to fit over the GSE tube) and it would have a considerably short LOP since the magazine is still in front of the pistol grip/trigger assembly.

I think most bullpups have the magazine and trigger assembly swapped for this very reason. better weight distribution and handling. An AR receiver with short stock and an 18" barrel will be extremely front heavy.

technique
10-14-2009, 1:23 PM
but then, you would have a rifle with no stock.

But he is attempting a Bullpup design...

Perhaps he can mod an A2 or a RRA entry stock and shorten them up, open up the buffer tube hole to fit over the GSE buffer....Use your imagination:)

Mr.Poopypants
10-14-2009, 1:31 PM
But he is attempting a Bullpup design...

Perhaps he can mod an A2 or a RRA entry stock and shorten them up, open up the buffer tube hole to fit over the GSE buffer....Use your imagination:)

I've actually got what might be a fairly solid design idea. Consider two areas of a flat top AR - the upper receiver rails and the breakdown-pin holes...they are the crux of my design.

Dirtbiker
10-14-2009, 1:31 PM
The GSE (Gun Smoke Enterprises) pistol system is the shortest I've ever seen. I'm going with one for my AR pistol.

Unfortunately it won't work with a 9mm upper due to the design/weight of the bcg.

CSACANNONEER
10-14-2009, 1:49 PM
How about NO buffer tube and a gas piston upper instead?

jchen76@gmail.com
10-14-2009, 2:02 PM
From a recent post -
http://www.thefirearmblog.com/blog/2009/09/21/dsei-09-new-design-hk416-sub-carbine/

I wonder what buffer system is on this prototype.

NSR500
10-14-2009, 2:34 PM
The shortest an AR can get is without a buffer tube. That would only apply to the .22rimfire, and any AR caliber capable of running with a Delayed Impingement gas system like the ZM Weapons/Para found here:
http://www.defensereview.com/para-tactical-target-rifle-pttr-clean-running-tactical-ar-15-carbine/

http://www.zmweapons.com

http://zmweapons.com/LRs.jpg