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11/20/2019 5:07:11 PM
Posted: 10/30/2006 6:59:24 AM EST
I have a Bushmaster M4-gery that has a 16" stepped barell, is this a "mid length" or a "car length". Is this definition barell or gas port dependant? Sorry for the crappy spelling ~lol~h.gif
Link Posted: 10/30/2006 7:06:20 AM EST
well, i dont believe that bushmaster makes a middy yet, so i'll say its a CAR length that you have

the "stepped" part has nothing to do w/ the gas system length; "stepped" could refer to a couple of things, but usually to either: the stepped down portion on an M4 bbl (the cut out) for attaching an M203 or the stepped down cut on the muzzle for a propper crowning

got a pic of the bbl?
Link Posted: 10/30/2006 7:08:09 AM EST
Bushy m4 style barrel is CAR length

CAR length and midlength are gas port dependant.

Link Posted: 10/30/2006 7:18:47 AM EST
[Last Edit: 10/30/2006 7:19:30 AM EST by engineer2001]
Yeah - "mid-length" refers to the fact that the gas port is at 8.5" down the barrel instead of 6.5" like a CAR or 11.5" like a rifle.


Any profile barrel could be considered "mid-length" if it had a gas port at 8.5" (HBARs, M4s, lightweight, etc).
Link Posted: 10/30/2006 7:20:02 AM EST
Its for the use of a 203 im sure, but then again im a newby so I wont say that ~lol~.

Link Posted: 10/30/2006 7:21:44 AM EST
[Last Edit: 10/30/2006 7:22:01 AM EST by ALPHAGHOST]
Link Posted: 10/30/2006 7:23:19 AM EST
Thanks loads for the info, sorry for the FNG question...
Link Posted: 10/30/2006 7:40:50 AM EST
No problemo - we wouldn't be answering if we minded the questions. How else are people supposed to learn?

Welcome to AR15.com, by the way. I haven't seen you around before now.
Link Posted: 10/30/2006 8:24:19 AM EST
Well ive been a "lurker" for some time, but after my detent spring went ~pflllliiiinnnnggg~ across the room somewhere I figured id ask about that, and everyone was so helpfull I figured id ask another ..opened a whole can of wormes for yall ~lol~
Link Posted: 10/31/2006 1:14:05 PM EST
I am a noob too! Great writeup on the AR operation and gas factors on ejection. Taking a barrel and putting the gas port in different locations would affect the rifle timing, the way I undestand it.

I have not bought my upper yet and I am looking at building a tactical build for a first time.

Does it matter to me where the gas block sits on a 16 inch barrel at this point?

Link Posted: 10/31/2006 2:38:34 PM EST
[Last Edit: 10/31/2006 2:39:53 PM EST by engineer2001]
I'd go mid-length just for the lower pressures meaning (most likely) longer bolt life, smoother cycling, and less recoil. The only reason to go CAR-length is to get the wider assortment of accessories that fit them and the (usually) lower prices. In addition, a 16" middy can use a standard M7 or M9 bayonet, and a 16" CAR cannot. The "timing" issue (assuming you mean dwell time and such) is fixed by opening up the gas port wider for less barrel past the gas port.
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