They'll work just fine, especially at 100 yards.
Here's everything "wrong" with what you're doing:
- your rifle's twist quite a bit faster than it needs to be
- they're probably not good hunting bullets
- they're probably not match-grade target bullets
- they'll be blown about by the wind more than a 150+ grain bullet (a 10mph wind that blows a 165 grain Hornady Spire point bullet 0.9" sideways at 100 yards, will blow a 100 grain Hornady bullet 2.4" sideways; not a big deal either way, especially since 10mph is a lot more wind than it sounds like!)
- the throat in your rifle is almost certainly "too long", in that you won't be able to load ammo so that your bullet is touching or nearly touching your rifling.
But if none of these is a deal-killer for you, have at it; they'll all safely go "bang", and zip right through whatever target you staple up at 100 yards
(BTW ".30 BR" is a benchrest cartridge, used for short range benchrest shooting for score. Picture a 2/3-length .308 Winchester).