Bob:
First off let me thank you for your reply.
1) I do more still hunting and standhunting.
2) 75 to 150 yards would be nice
3) As far as cost goes, try to keep under a $1,000 or less perferably
4) threshold of pain well lets say I am not all that big.
But any adivce at all would be helpful.
Ed
Ed,
First off, I think you should lose the notion that a shotgun is a rifle. In Shotgun Only Regions across the country, hunters are not allowed to use rifles because of the range of the projectile (usually over 300 yds.). Shotguns using slugs, on the other hand, are most likely going to be limited to about 100 yds. Actually more like 75 yds. effective killing range. Now that's with a 12 gauge gun. When you step down to 20 gauge, you are cutting back on that effective range even more.
Next, I would NOT recommend that you use an auto loader. If you are waterfowl hunting, an autoloader is ideal, but not for slug hunting. If you are after the most accurate, hard hitting gun, then you want a pump or bolt-action. There are a number of very good modern pumps with permenantly mounted barrels just made for deer hunting. These guns have the rigidity, and rifled barrels needed to put the slug into an 1 1/2-inch or better grouping at 75 yds. You don't need to spend $1000 for a good slug gun.
Mossberg makes the model 500 pump w/ 2 barrels (one is a field barrel w/ screw-in chokes, the second is a deer slug, rifled barrel) for well under $500. Mossberg also makes a great bolt-action slug gun that is made for w/ rifled barrel.............. My favorite is the Ithaca M37 Deerslayer with a smooth-bore barrel that has the necessary sights and choke designed for foster-rifled slugs. Foster slugs are cheap...... about $3 a box compared to $10 plus for sabots.
Knock-down for deer is not better using a rifled barrel, actually the foster slug does that best. If you require maximum range, then you want 12 gauge/3-inch chamber with rifled barrel using sabotted slugs. Good Luck, and ask a lot of questions when you go into a sportsshop to check out the guns.