I believe the 500 grain bullets are Hornadys and designed for the 458 Win Mag and the Lott, twice the velocity plus. Going to hand loads and a softer bullet should give better results. Hawk Precision bullets are notoriously soft at normal velocity and available in thinner jackets.
The hard, heavy Hornadys are also a ricochet hazard and the lighter bullets would be safer, especially at night.
Other solutions may not work well in a semi automatic rifle. I shoot a subsonic 45/70 Encore and have good results with wide flat nose and pure lead paper patch bullets, neither likely to feed in an AR.