180 grains of 2F--why?
Assuming a .610 RB at 340 grains that's 520 grains of mass exiting the muzzle at what? 1800-2000 fps? No bloody wonder you hurt. Shorten your loads to about 1000-1100 fps and hurt the target, not your self.
If you insist on heavy loads such as that, consider a Jeager with a shotgun style buttplate.
I was taught to shoot by my insane uncle, a WWII era Marine DI. If he had ever seen my right elbow fall below shoulder level while shooting off hand, he'd have knocked me half silly. Same if he saw my left elbow anywhere but directly below the fore end. (He was kind of like R. Lee Ermy except not so wussy.)
Just sayin' is all.
Three Hawks