I probably will keep the Capco/"PA" marked A2 upper just in case, but for now I will covert it to A4 configuration because that is the what I like now, but my question, all the other parts looked to be USGI issue, such as buttstock, grip, handguards and the bolt carrier was a old Colt smoothside and the bolt itself was FNMI marked. Now was this possibly one of the A2 upgrade kits that was surplused out sometime in the past on somebody put this upper and stock/grip on a commercial receiver? I took a closer look at the fire control components and the trigger, disconnector and the hammer were the burst configuration, the hook that normally contacts the auto sear was ground off. The burst cam and spring were missing, and a standard run of the mill semi-auto safety was installed. I have replaced the fire control components with a set of used Colt AR15 ones I just purchased at a gun show recently to get the burst control parts out of the gun.