Well, I'm not a TX Hog Hunter, but I do hunt them in Arkansas... About the biggest we see here is 250-300#, generally they are around 150-180ish.
I have a 7.62x39 AR Pistol with a 10" barrel that I use sometimes. The 7.62x39 takes it own caliber specific magazines.
I load the 123 Barnes TAC X and get sub 1" groups.
I also have a Ruger AR556 in 450 Bushmaster with the 18 5/8" barrel. The 450 uses a single shot follower in a standard mag, or you can just buy 450 magazines.
With Hornady 250 FTXs this thing is scary accurate.
I have had some success with cast in the 450 with the MP 45 Ruger Only Powder Coated.
I have Tromix Linear Comps on both of them that really helps to control the muzzle blast.
The 300 BO barrels have a 1:7 twist I believe.
The 7.62x39 barrels have a 1:10 twist
Not sure on the 300 Hammer
Hope this helps.