AR15: Replacing upper with...good or bad?

[gunderwood]

would the

WTS-AR-15 Match grade upper-NIB $550

Postby kamikaze

http://vagunforum.net/firearms-for-sale ... t6863.html
in the marketplace of this board be of use. You did say mid and "It is a 20" free floating heavy barrel, detachable carry handle, hooded rear sight shaved front tip.""brand new bushmaster competition A3 upper reciever"

just a thought,

Mid in this context means mid-length gas system. What you referenced is a rifle length gas system and is longer. The mid-length gas system is designed to fix the timing issues of cutting down the barrel and moving the gas port closer to the chamber on a 16" carbine. The government uses a shorter system for their 14.5" barrels which is commonly called a carbine gas system. Above 18" or so the mid-length gas system is inappropriate and you should use the rifle version.

IIRC, there was only one major manufacturer who made mid-length gas systems on rifle barrels...Bushmaster Dissipator and they did not have a good reputation.

[gunderwood]

For clarification:
http://cheaperthandirtcom.blogspot.com/ ... guide.html

I will disagree with them on their suggested barrel lengths though. The carbine gets to be too much around 16" and the mid-length around 18" IMHO. The gun will usually work, but guys who run long barrels on carbine gas systems tend to have more trouble shearing off locking lugs.

Edit: IMHO...

Carbine: 12-14.5"
Mid: 16-18"
Rifle >=20"

Good link: http://www.ar15barrels.com/prod/operation.shtml