I just finished building one yesterday with a Armscorp receiver I purchased some time ago, will shoot it tomorrow for the first time if the wind cooperates. Armscorp are not perfect but it wasn't bad, only had to do a little stoning in two places and ream the hole for the follower rod catch for proper fit of the parts. Barrel is 6 groove 1 in 10 mid weight match from the CMP, stock is from Fred's, bolt is Springfield Inc., Oprod and gas cylinder are Smith Ent. (SEI) new offerings. Most of the parts I bartered/traded for so I don't have a lot in it. My flash hider is Calif. legal type (I don't live in Calif) so still looking for a GI flash hider but this will do for now. At last minute found my metric elevation knob is cracked, always something, will use a M1 knob for now.