Like others have said, a good trigger and barrel are essential if you're serious about competition shooting. 16" barrel is plenty for 3 gun.The ALG trigger is best solution unless you're a benchrest shooter. Couple it with a Blackhole Weaponry barrel and you are on your way.You can buy a BHW barrel from SAA and they will give you a stripped upper.I've built so many for myself and others, I've lost count, but the upper you build will outshoot the upper you buy if you do it right. My favorite build has made believers out of guys at a range near me when they challenged me at 25 yards for accuracy. I told them I wasn't a shooter, but my rifle was and after they each (3 of them) put 5 rounds each into a target, I dumped 2- 20 rd mags into one 2 inch hole using a red dot-silence ensued.The BHW barrel is key.Installing it with a reaction rod also makes a world of difference as you don't torque load the upper (kinda' like warping it) so your rifle repeats placement, less fliers. Aero Precision makes good parts as does PSA and others. Used lots of both, and current rifle is a PSA limited run actually done by FN before they went commercial. Only made about 500 of them. Other favorite was an Umbrella Corp SPR build and of course I named her "Alice".Good luck on your build, need any help or info, yell out.