Last week we looked at the Black Hills .40 S&W load using the TAC-XP. DoubleTap's load has a muzzle velocity that's only 31 fps slower than the Black Hills offering, but this small decrease substantially changed the terminal performance of the bullet. This is unusual. Generally, it takes a much larger velocity variation to result in so great a difference. In this case, however, a reduction of 31 fps actually caused the bullet to have greater expansion, while penetration was 2 inches less. Depending on the velocity and the bullet, you can reach a threshold where a few fps indeed cause a large variation in terminal performance. Regardless, the TAC-XP, whether loaded by Black Hills or DoubleTap, is a solid performer in .40 S&W.