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View Full Version : DI lengths & piston lengths



AlcoholicSanta
03-28-16, 11:17
alright so, I recently saw a ridiculously short upper on a registered FA lower that had a 2" barrel and a really short gas tube.
The bullet tip actually stuck out of the barrel but, it functioned in both semi and full auto.

Now I know that the length of the gas system and the length of the barrel dont really matter or go together.
Theoretically you could have that ridiculously short gas tube on a ridiculously long barrel.
Leading to, presumably, a ridiculous cyclic rate and ridiculous wear & tear on the rifle.

So i've seen Krinks & Krink'd ARs.
Many.

What I want to know is, how long could a piston be?
I mean I see rifles with pretty long ones.

Noreen's .338LM is also something like a DI/piston combo from what i understand.
The piston doesn't go all the way to the gas block and instead it's rigged to a tube.

I've also seen the AK .50 bmg concept.
Which could work pretty decently with heavier bullets, slower burning powder, lower pressures, yadda yadda.
The russians also made what is essentialy an ak in their own iteration of a .50 caliber anti material round

so yeah, after seeing how short they could be (and also seeing functioning ARs with the barrel cut to sit flush with the gas block) what is the ratio of the gas system length vs the barrel length?

I personally want a mostly polymer/carbon fiber rifle in something beyond 308 but I plan to suppress it and while I like how short gas systems look combined with long overbarrel suppressors, I don't know if thats how I should go about it.

What has come close is RND's piston driven magnum precision rifles & some of NEMO's stuff.
but those are 15lbs+ unloaded.
which i do not mind per se
unless I'm in a building, all that matters to me is velocity & maximum range.

I know I'm going to do a mostly custom and therefore progressive kind of build, same way with a computer, as I can't afford to drop 30k at once on literally anything.

This is something I want to know, though.