how well would a 12-gauge solid slug work, and what's the effective range on those?
Depending on the design of the slug and the range at which they impact, body armor can stop a 12 gauge slug. However, the recipient of the shot will be hurting for sure. Even if one's body armor stopped a slug, the blunt force trauma would be tremendous and it would be normal to expect broken ribs or internal bleeding....again, all depending on slug design, powder load, and the range involved.
There are some who will disagree with me but I consider the absolute maximum effective range of 12 gauge slugs to be 100 yards because they don't hold accuracy past that unless you are using a rifled slug barrel. Some deer hunters take longer shots with specialty slug guns. Slugs are phenomenal for work inside 50 yards. They are extremely effective in
CQB/CQC. The beauty of shotguns for tactical work is that a well-trained operator can select the right shell for the right job. You can breach doors using your breaching rounds (powdered lead or even birdshot in a pinch) and then top off with buckshot or slugs before continuing with clearing. Most trainers advocate the "shoot one load one" approach to shotgun usage in a tactical environment.
The Benelli M1 Super 90 is one of the best semi-auto shotguns available. It allows for selective shell loading and it has an incredibly fast and reliable action which will load and fire many different kinds of loads. It remains one of the preferred shotguns for 3-Gun matches (which is what I use mine for) and it can also be fitted with a picatinny rail on top and a small red-dot sight for fast sighting and accurate slug placement. Currently, the
Benelli M4 is the "hot" new model which has started to supplant the M1 Super 90. For semi-auto shotguns, the
Remington 1100and 11-87 are also very good as is the FN SLP. For pump-action shotguns, the Remington 870 and the Mossberg 500 series still pretty much rule the roost. Both are very good and extremely reliable I am not a shotgun guru but I personally prefer to use an M1 Super 90 for competition and a Remington 870 for duty....although I don't use a shotgun for duty purposes very often.
The
Wikipedia article on combat shotguns is actually very accurate.