Needs some work with a file - Lantac LA00221 Advaced Receiver Multi-Caliber

Had to file both the top lip of the ejection port and the forward assist. Tried multiple mil spec and aftermarket parts. Detent for ejection port couldn't articulate until after I used a round file. Ended up using a fcd epc. The forward assist took more work. Teo different mil spec forward assist, two different roll pins. Both would bind to the point they werent functional. If i had the 3/32 punch through in place of the roll pin it would work just find. Had to file down the yhe retaining face of the forward assist unil it wouldn't bind any more. Seems like the hole for the roll pin was drilled too close in to the center of the forward assist. Overall it looks good, but I wouldn't recommend this. Both the vltor billter upper and silencer co billet upper are better options.