650 shouldn't be too hard with a 20" not sure, but I haven't done the math. I'm pretty sure a 20" will keep you super sonic out to 650. But if you are talking about 800, there's a lot of special considerations when you get to those ranges. Bull barrels would be better, as would longer barrels for more velocity. Also when you start talking about 24" bulls, you make need to look into a stronger upper reciever to handle all that weight. Also handloading 77+ grain projectiles would be key.
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