Not sure how much money your looking to spend.
I have 2 Rem. 1100"s and love them.
Not sure if they make one in 3" but I know you can get
an 11/87 in 3".
If they shoot anything like the 1100 ya can't go wrong.
I recently almost bought a Browning Gold Hunter 3 1/2".
After reading numerous reviews, many complained of
this gun not cycling properly.
So I couldn't warrant shelling out $600.00 for a used gun with that kind of rap.
To get reviews you can Google it.
Just enter the brand, model and type in reviews.
You will love having an autoloader! I have owned and used Remingtons, Bennelis, Charles Daly, and a Beretta.
All of them worked just fine.
My favorite is a Benelli M1. It just feels good.
Some people have whined about the Charles Daly, but my own personal experience has been very good. No problems. Cycles everything I put through it just fine. Plus, I have seen them used for us low as around $250.
Lets face it. You're buying used. You won't find many Brownings(except the old A5's) or any of the "new" style autos for that price. My advice, most any name brand, Win. Rem. Brown., is a good gun(depending on price). I have an 11-87 that the only time it's let me down is when I dropped it in a swamp. The only gun that wouldn't be on a "list" would be the Charles Daly. I know two people that have one and they both love it.
Here's a good idea for you. If you find a gun post up here before you buy it. I can't vouch for everyone, but most of us would give you an honest oppinion of the gun.
For the last 15 years I/we have used an 11/87 and that puppy is super reliable. Keep the gas piston clean, change the O-ring yearly, and change the recoil spring about every 5 years IF you use the gun a lot and you will have one of the best autos made. NONE of those things to do is mandatory but it is preventative maintenance. The gun is soft on the shoulder too.
For the last 6 years I have been using a Benelli M-1 and it runs everything I put through it without a hitch. Maintenance is less than the 11-87 because there is no gas piston to keep clean.
Either one would work from clays to geese and would serve you well.
You can pick up used 1100' and 1187's for much less than $500.
I have an 1100 my step-father bought almost 40 years ago to hunt deer with in Mississippi. Gun still looks and shoots like new. I did have to have the gas seal replaced once about 10 years ago.
I use mine very very little as it doesn't really suite my style of hunting. My gun has a plain fixed full choke.
My biggest complaint is the shear weight of it. If you did more shooting than walking it's a fine, but I'm the other way around. After about a mile or so it carries like a lead pipe. I carried it in a few miles last year on a grass road through the mountains for grouse (just wanted to get it out), and I was about ready to leave it where I turned around.
If you are a guy that will just toss it in the boat for waterfowl or carry it across a field for turkeys as semi auto will serve you fine.
I have had a Stoeger 2000 since they first came out. The only problem I ever had was it got dirty out in South Dakota while driving in the back of a truck on dusty roads and got a little sluggish...my Super Black Eagle also got dirty on the same trip and would NOT work. The Stoeger still worked...go figure. I actually think the Stoeger is a better design, keeping the recoil spring under the forearm, instead of the buttstock. Obvioulsy, Benelli thought enough of Stoeger's engineering and their copy of Benelli's rotary bolt design, that instead of suing them, they bought them. (google it)