Bramble,

Sorry to disagree with you, but any and all BP load would be already quite a long while subsonic before getting to 900... Typically, even the best and fastest LR BP loads will go drop through the sound barrier before getting to 300 meters, and most even before the 200 mark (remember, 1120fps), and that might even be stretching it for a 45-70. Typically, bullets arrive at 1,000 around 800-850 fps.