Being some guns(NEF) need to much work
to fire bmg primers, it easier to
do the following with adapter bushings.
Here is picture of cases for primer
comparisons.1st is regular bmg
primer. 2nd is adapted to a shotgun primer.
3rd is adapted to large rifle primer.
Of the 2 adaptations, large rifle is
easier to do, just ream out pocket, thread in adapter, but adapting shotgun primer
you have to deepen the original primer
pocket a little, then thread and screw in
a bushing.These two primers give about
100 fps less than bmg primer.Ed.