It's like 1:23 or 24. It's a bit slower than the Mode 500. I know Big Horn Armory proof tests the rifles at 90,000 psi, but that doesn't mean that can regularly handle that kind of force.
The AR doesn't have a cylinder gap to relieve some pressure though I think that when guns go boom they over pressure before the bullet has even left the case so that's probably neglible.
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