I don't deer hunt anymore but I've used 1 oz. Remington Sluggers in the past. If you want a little more knock-down power, you could go with something like Federal Power-Shok 1 1/4 oz. Magnums. To minimize the stress on your muzzle, I wouldn't go any tighter than IC with slugs.
Btw... In case no one's mentioned it yet, you're a disgrace to the bird-hunting community and I hope your dog disowns you.