I have the Winchester SX- AR
It's the same basic gun, 20" heavy barrel, 10 round mag. I use Hornady 150 grain SST. Works great on deer, pigs, coyotes. It's such a soft shooting gun, very comfortable and its becoming my go to gun for hunting.
The SSTs group really well in my gun (1 moa). The only things that has grouped better is Hornady 178 grain Match.