Slugs have come a very long way and I would not hesitate one instant using one out to 100 yards on anything up to and including elk (150 yards on deer sized critters). We have 7 setups (5-12 ga and 2-20 ga) that all shoot less than 2 MOA (a few are much closer to 1 MOA and cloverleaf groups are not uncommon) at 100 yards. Muzzle velocity is 1700 to 1900 fps (20 ga and 12 ga respectively). We have had outstanding luck with Barnes Expander slugs made by Federal (now replaced by Trophy Copper by Federal). IMO I wouldn't trade my 12 ga for a 30/30. They are not 30/06s, but they have come a long way. Also on the plus side, one may be more adept at shooting a shotgun than a rifle if you are a bird hunter or clay shooter. YMMV
