I have a 7x65r and 16 bore combination. The 7x65r will do pretty much anything that a 30-06 / 270/ 7mm R.E.M. Mag will do. I have used it to take red and roe deer out to 200ish yards. I have shot it out to 350 and was repeadidly hitting an 18 inch sized rock.
A 16 bore slug certainly will act as a good stopper, but so will the 7x65r.