Well, I've finally given up trying to get my AR15 to shoot anything close to a decent group. The best group that have been able to attain was with 25.3 grains of H335, CCI primer and 55 grain Hornady soft point. It measured 3" at a range of 75 yards. I had mounted a Leupold Mark 4 scope and I couldn't even get the scope sighted in because of the inconsistency. Factory loads spread about 8"+. So, sadly, back to Bushmaster it goes. The sad thing is that my brother-in-law has the same rifle and my hand loads using 62 grain Sierra bullets group sub-MOA at 100 yards.
I just wanted to thank everyone who has provided both encouragement and input over the past couple of months - I truly value your experience and willingness to share your knowledge. This site has been an awesome experience!
Thank You
Paul