This is my first carbine build,  I shoot the 77 gr and 69 gr bullets more than the 55's.  I like the idea of the chrome lined 1-7 twist barrels.  My question is;   am I going to have problems shooting the heavier bullets with the short gas system?  I.E.  ripped off case rims as I have seen with some carbines or is that some other problem with the gas system?   I am looking at the mid length 1-8 twist RRA barrels also thinking the extra two inch gas system might be the way to go - but then - the chrome lined barrel would out last the SS barrel.   Any ideas?   Maybe a 14" barrel with a perm installed flash hider?   think that would work better?     I want at least  1MOA from it ,  I get that with all my handloads through my 20" barrels w/1-7 twist - free floated