Here is picture of the bolt for my big gun, the 700HE.
It is holding a 700HE long case. The caseholder extraction system
can headspace a BMG rimless case,no belt, so you could
put on a 12ga barrel, straighten case more, from .700 to .729"
and have the rimless 12ga. Could straighten case for a
.750" bore, even to 10ga(.775") with a little thinning of the
top one inch of the case. Experimenting is interesting
to say the least. 700 slugs in pic are 1000gr Woodleigh,
1000gr PA, 825gr Copperhead Custom(CC), 770gr FP CC,
1000gr HP CC, 825gr HP CC..Ed