One word of advice. I have a Knight .50 cal. Bighorn. The rifle wears a 22" barrel and is amazingly accurate at 100 yards. My standard load is a 250 gr. Hornady SST and 100 grains of 777. I sighted the rifle2" high at 100 yards. I moved the target to 150 yards and I was approximately 9" low. At 200 yards I was amazed I was shooting 19" low. Just as a trial I tried 150 gr. of 777 and it only decreased my bullet drop by 2" at 200 yards. I didn't try it at 150 yards. Your rifle has a barrel 6" longer than mine and that should help with velocity. You might look to the T/C Shockwave in 200 gr. with 130-150 gr. of powder if you are truly considering shooting 200 yards with you rifle. Make sure you actually shoot your rifle at 200 and don't rely on any ballistic tables you run across.