12 ga slug is effective out to 100yds with the right combo of gun and bullet. But its definately not even in the same league for a deer cartridge as the 7mm-08, 270 win, 243 win, 30-06, etc. (I mention those 4 because those are the ones that I've had). I currently have a 44mag Marlin 1894, Ruger M77 in 270 win, and Rem 700 in 243 win. If you want a cartridge that will give you everything for a deer go with the 270, short, long, the 270 is a time prooven shot maker. And if you are concerned about recoil, remington makes a recoil manager shell that is comparable trajectory wise to a 130gr or 150gr standard load.