I'm an idiot; so, here's a quick video on how to replace the magazine catch on a Foxtrot Mike Products .45 ACP lower. FYI, Foxtrot Mike has awesome customer service!

Assembling two AR pistol lowers. One of the lowers is the Foxtrot Mike Products .45 ACP FM-45 lower receiver, and the other is a "standard" AR-15 lower receiver I picked up from Palmetto State Armory.

A quick look at the Foxtrot Mike Products .45 ACP stripped lower receiver. I do a quick comparison to a "standard" AR-15 lower receiver and cover a few of the similarities and a few of the key differences.