I have a Predator pursuit with a 20" barrel and have gotten (IMO) decent results with my hand loads from it. I've gotten 1/2" groups at 100 yards with most of the stuff I've tried, but I'm still looking for that load that every hole touches and is tighter than a half inch. Not sure if I'll ever get that out of an AR but I'm [beeep] sure gonna try! Never heard anything good or bad about stag so I cant help ya there, but I have heard a lot of good about rock river which is why I have one. My dad always told me to always save my money for the best it can buy, and after the research I did before I bought mine, rock river seemed like it was one of the best in the business next to LMT which I did not find out about until recently. Keep researching each brand but really consider the rock river. I have not been disappointed in how it operates (other than my own hand loads) and I'm sure you would be either.