I’d rather use my specialized AR-10 on the deer, and the tricked-out/accessorized Beowulf .50cal on the wild boar.
Sounds like the Bow Mag is a cute novelty, but i it didn’t ‘work as advetised’, you might be trailing that wounded animal for a while, to finish the job.
The AR-10 lower is different than the AR-15 lower. Colt does make one that will do 5.56 and 7.62x51 but they are the only one that I know of.