WE MSK/PMAG compatibility
 

Interesting compatibility test video by RA-Tech, shows results of testing different WE mags in the MSK & PMAGs in other WE guns.
Looks like 4168 owners wanting the PMAGs may have to do some filing to get them to fit
we msk mag compatible test - YouTube

I think it might be because the Pmag is a copy of a gen2 Pmag and not a gen3. The real steel have the same problems, one of the reason for the gen3 pmags.