Well...not exactly today, but recently I stripped my new DPMS BCG to clean and lube it, and then couldn't get the stupid firing pin retaining cotter pin back . As nearly as I can tell, it takes a 5/64 cotter pin to fit exactly...and those don't appear to be available anywhere at Rona or Home Depot. YESTERDAY I got a proper pin [not a cotter pin] at the big gun show...
And it's perfect. Gonna order a couple more.
TODAY: I picked up some Magpul XT Rail Panels to put on my DA556. Man, those suckers don't go on easily.