Pmags  . my lancer  died.   ??

I've run both M2, M3 and Lancers; my observations were the Lancers seemed more OAL-limited when shooting anything other than M193 or 55gr .223 FMJ.  I loaded some Black Hills 69gr OTMs in three of my Lancers to test about a month, which caused some hang ups with a speed loader if the rounds weren't completely pushed against the back of the mag.  The leading edge of the bullet would catch on the front lip of the magazine if not.  Haven't tried any 75 or 77s to see if the issue occurs there, but I know my PMAGs took all of those rounds without incident.  Two weeks ago, loaded 55gr AE .223 and Black Hills 60gr VMAX rounds without incident in one of my Lancers without any issues.  Other than that, no feeding or cycling issues to report on the Lancers.  

All told, I think Lancers are a little less forgiving with regard to internal space than PMAGs.