Welcome to the forum Schick! A 16 or 18 6.5 Grendel AR-15 makes a handy size. I also have a 12 pistol build which could be used for hunting in dense terrain. The high ballistic coefficient bullets helps a lot with the 6.5 Grendel. The 129 grain Nosler AccuBond Long Range (ABLR) expands down to 1300 FPS and has been used effectively in hunting. Nosler and Precision Firearms sell ammunition loaded with this bullet or you can load your own.
Nosler list the 129 grain ABLR at .530 G1.
https://load-data.nosler.com/load-data/65-grendel/
Nosler list the 129 grain ABLR at .530 G1.
https://load-data.nosler.com/load-data/65-grendel/