This involves the stock MP-15 Sport II AR I bought a couple of months ago for $623. The first thing I did was mount an Leupold Mark AR Mod 1 3-9x40 mil-dot scope on it with a 1 piece Leupold mount. The handloads were benchrest quality with less than 2 mils of runout on the finished round.
The target below shows the results from the bench at 100 yards, and this is the best I could do with the stock rifle. For right out of the box, 2 MOA isn't half bad.
While the S&W stock trigger wasn't absolutely vile like most AR's, it was a stock AR trigger at about 6+ pounds, and there was clearly room for improvement. As such, I sent the lower in to JP Enterprises, which is local, and had them put in their "Original JP trigger", which is not as good as their full match triggers, but it's better than 95% of the match stuff out there. The cost installed was $220, and they individually grind the trigger and sear to be dead nuts perfect. (That's why I did NOT try the cheaper DIY trigger kit!!! :banghead: )
The target below is the final convergence on the bull with the scope dials, and after I stopped fiddling with the scope the single hole group is what I shot. Looks to be 1 MOA straight up!!
This target is 20 rounds fired after that, and apart from the three fliers where I thought of Hillary and damn near barfed on the gun, it's a solid 1 MOA group. A few days ago I was talking to a "real gun junkie" who had Class IV ATF rifles (in wildcat calibers, no less!) and he had mentioned to me that upgrading the trigger on my stock M&P would be a huge improvement.