Militia use is not the same thing as hunting use.
I think this weapon's normal rifle round is inadequate for large game, and the shotgun and grenade launcher are inappropriate for hunting game(as you recognized and noted.)

I like it, while creative I found the "not man fireable" demonstrates little imagination.
The rifle/ Granada launcher combo is also a little mysterious. Do you need a rifle? Or a grenade launcher? Rarely have I needed both. I mean I want to take down the deer not blow up the forest.

Well hey, it's a beautiful day, get out there and have some fun!