I use, like and swear by BT's, I run 140's out of my 7 stw at 3550 fps and mostly get an exit. I do stay off the shoulder at less than 100 yards. I also shoot the 115 gr BT in my 25wssm at 3000 fps, it exactly duplicates the performance of the 110 accubond at 3075 fps.
Guys years ago the BT's were all just thin skinned varmint bullets, then nosler revamped them, they made them exactly the same as the nosler solid base boatails, except they retained the polymer tip in the weights for med. game, how do you know if they are varmint bullets or game bullets, look on the package, game bullets come 50 per box, varmint bullets are 100 or 250 per box. Back in the day when the 7mm 140's were packaged 100 per box I had a couple failures. Have had nothing but good results since the bullets were changed.
RR