Hello all,
I'm not new to shooting but am definitely new to building AR's... this is the result of my first attempt, and I think I have a problem. I need some advice.
I just assembled a PSA LPK into a brand-new Aero Precision lower, and after I finished I noticed what appears to be a small crack along the edge of the forward "ear" that holds the roll pin for the bolt catch. I know this was not here before assembly as I inspected the lower very thoroughly at the store (Surplus Ammo & Arms in Lakewood WA). When I put the lower together, I secured it in a magazine well vise block and used a standard pin punch along with a small hammer to install the roll pin. I initially tried using the "vise grip" method but wasn't having luck getting the pin started, so I changed to using the hammer and punch. I have a factory-assembled BCM that I used for comparison throughout assembly and also consulted a pictorial instruction set I found on Arfcom.
Both ends of the roll pin looked the same to me, with neither more tapered than the other. I drove the pin in starting from the rear of the receiver. I'm not sure if that makes any difference but I've seen photos of it being done both ways. The pin was hard to get started, went easily through the bolt catch, and then became hard to drive again as it went into the opposite "ear" of the lower receiver. I thought I did fine as I put no big scratches in the receiver and the bolt catch functions properly. And then I saw the crack.
I know I must have done something wrong. Do you think this is a superficial "finish" crack, or is it going to propagate until the bolt catch "ear" eventually breaks off? Is there anything I can/should do about this? What did I do wrong, and how can I avoid this on future builds? Thank you all for your time and help.


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