Man there are alot of different manufactures out there! I bought mine a few months ago!I picked Bushmaster!!A shorty with a 16 inch Heavy Barrel and with the A1 upper for simplicity! Plus I just dont care for the A2 sights!!I have shot over 700rds out of her,I use thermolds and USGI Mags and all types of ammo to see what she likes! My Rifle has never had a FTF!! Its Perfect!! Plus the accuracy is outstanding !! That made me to decide to buy a 20 inch N. M. Target Barrel with a A1 upper to switch back and forth!! Had a Burr that needed to be ground off but other than that This Upper is VERY VERY ACCURATE!!with M855,SS109 Lake city and Santa Barbra it shoots all Three rounds Touching at 100 yards with NO SCOPE!! out of the 55gr. FMJ'S Wolf,PMP are the Tightest shooting than Q3131, American Egale,S&B,PMC!! I havent tried any JHP yet but I do have some 69gr.BTHP and 40gr. Ballistic Tips I will try next time!I'm very happy with BUSHMASTER and the Custermer Service is Outstanding!!I still cant get over how good the XM15 realy is!!