In 31.5 years of AR15 ownership, assembling, shooting, and trading (I've had a remarkably high number of ARs pass thru my hands) I've have yet to see or experience a single lower receiver failure. I did have an EXTREMELY low quality cast lower in the early 1990's that was grossly out of spec....but it still worked.

This is why I've sold my extra complete rifles. I bought two spare LWRC uppers as replacements for the couple of complete rifles I kept. I have no worries about wearing out the complete rifle lowers, but the uppers I could eventually wear out.

JYD #123 The great one formerly known as Architect.

I am now a fictional British television police officer (currently a Detective Sgt) at Thames Valley Station. My governor is Detective Inspector Fred Thursday and it’s 1969.