The 300 Varmiter is just a hot hot loaded 300 WSM , I think their maybe a little freebore or some other nonsense , if you have one that will shoot a 125gr BT to 4000fps , that same bullet will drop right into a TC Encore (which by the way should never be chamber for the WSM anyway but some companies will) and if that round is set off in the Encore some realy bad things are gonna happen !!
I know a guy (No names here) that can get a 180gr Berger to around 3600 fps out of a 7mmx338 Lapua , well once anyway
just gotta use a good powder like those used in 6mm PPC cases and filler up
you know you'll never live that down !!!