3 year Study results of QCB Upper & Grendel

[LRRPF52]

After working with my 16" AA barrel/bolt combo in a Gen I MGI Quck Change Barrel Upper, I have made the following conclusions:

Finding sub-MOA accurate loads was an exercise in futility with the barrel mounted in the MGI Gen I upper, which I bought used in 2006.

I thought I had a mediocre barrel, and was only able to get one barely MOA group with 120gr SMK's.

After seeing that I was able to shoot a 6 or 7 round group with a .5 MOA vertical spread last week with Precision Firearms 123gr Scenar loads, but the horizontal spread was like a duckbill shotgun, I knew something whacky was going on.

I decided to drop the barrel in a standard AR15 upper, slap a rifle-length float tube on it, and take her back to the range.

After my trip to the range today, the first group out of the pen was .792" for 4 rounds, no flyers, no cherry-picking, just a nice sub-MOA 4-round group. The gun is extremely light, and very difficult to keep on-target, but it is a shooter.









My interest in it was more as a nice little hunting carbine, which it was capable of with 1.5-2.0 MOA accuracy, but the little ER Shaw AA button-rifled pipe can spit pretty tight for a $269 barrel/bolt combo.