Mid Length 16" AR vs. Carbine Length

[Abraham]

A helpful person sent me the following: The seals have a special made rifle given to marksmen that has a 16" barrel. It is the RECCE rifle, and it's an 'accurized' 16" rifle. It's like their version of the SPR MK12.

I did a little further research after receiving this info and found it used a C.L. gas system.

Interesting...

[gljjt]

How can you tell what you have? Measure from chamber to gas port?

If you have a carbine length barrel, unless you paid a slight premium for a ML gas system and it said on the packaging somewhere that you had a ML system, then you have about a 99.9% certainty of it being a carbine length gas system. You kind of have to go out of your way to get a longer than normal gas system for your barrel length. So.... If you have a 16" barrel, you most likely have a carbine length system. If you have an 18" barrel, you most likely have a mid-length system. And if you have a 20" or longer barrel, you most likely have a rifle length gas system. A mid-length system on a 16" barrel would fall under "custom features".

The fact that my 18" DMR barrel has a rifle length gas system is part of what makes it a "custom" barrel. (....the Wylde chamber, 1:8 twist, and stainless steel being the other "custom" features....)

Actually, I believe the Bushmaster is a 14.5" barrel with flash suppressor pinned and welded to bring it to just over 16 inches. The DPMS I have is a 16" barrel plus flash suppressor. Seems like from discussion here that for the weekend hobbyist shooter, carbine vs mid makes little difference if any for all practical purposes. However, perhaps the Bushmaster is correctly sized with a carbine length system with a 14.5" barrel plus permanent flash suppressor. I suspect the flash hider acts like somewhere between a barrel and open space for the length of the device in terms of gas pressure/release/etc. Doesn't really matter though, it is what it is.