Anyone out there ever have trouble getting the 187 BIB to the 1K target?
Yes, with a 10-twist, when going over about 3,100 fps. It's heat that does it, so you might get 3,150 with a smaller case, but no guarantees
Never with a 12+ twist -- at least, with a .300 Ackley at 3,200+. Believe Charles Bailey hit 3,400 using a 13-twist in his 300 Ackley & 34- (maybe 36-) inch tube.
What are you pushing them with & through?
Edit:
Since I bought his rifle, I have Joel Pendergraft's notes for his (now only IBS) record 10-shot target:
32" 12-twist Krieger barrel chambered in .300 Ackley,
a hefty charge of Rel-25,
Norma 300 Weatherby case w/ belt turned off,
Fed 210 primer,
187 BIB, using .020 bullet jump,
3,285 velocity at 15 feet instrumental.
This is essentially Alvin Johnson's .300 Ackley reamer (available from PTG), but without a belt