Re: Upper receiver effect on accuracy?
SOME are truer (tighter tolerances) than others but any good smith
can true the threads and face. I have used Larue, Mega, and Vltor with good luck as they are built a bit thicker and heavier in some areas to better support the weight of a heavier barrel. Raineer also has a match grade 1 I intend to try also---For all the combat,
3-gun, door kickers and such I have used any quality upper such as
Yankee Hill, Rock River, Bravo, Daniel Defense, Spike's, to name a few. I buy LOTS of stripped uppers and hand match them to a lower for a perfect fit--I am certain that all the quality parts
help accuracy, but I am of the opinion that the barrel, bolt, and trigger are the most important for utmost accuracy---Out to 500 yds my own barrels (cut-rifled and/or button rifled) have been equal but beyond 600 the cut-rifled seems to win out. Again these are just my personal evaluations--there is always the exception--2 recent builds without expensive match grade barrels are giving them a run for their money--1 is a Colt 20" gov't 1:7
and the other is a DEZ Arms 16" barrel---both exhibit sub-moa groups at 100! One day I intend to build a "cheap" AR15 and see
how accurate it can be with the least expenditure