Going to start the quest for a used O&U...

might be very hard to find something youd really want to own for 400.00

Agreed, add a "1" in front of the 4 and your options explode in many choices.

O/U's, like SxS's require more handwork than stamped out pumps and semis which is why GOOD one cost more. There are plenty of cheap ones around, and you take your chances on whether it will break sooner than later - the odds are for sooner.

The cheapest that has decent reviews is the Lanber from CDNN at around 600; there are some used possibilities that might be doable of your budget can stretch some more than your 400 figure. In reality, for 400, you are going to be hard-pressed to find a reliable used semi, let alone a reliable new O/U

Maybe if you tell us what's available for how much we can help you pick a good one. There are O/U's all over the price scales. Some aren't worth touching in all price brackets.

Instead of what to avoid I'll give you two maybes

I owned an American Arms Silver II for a few years and it was a decent enough gun, light enough for field work a I shot a bit of sporting clays with it.

If I was looking for a used o/u I'd look for a 70's era Miroku, I passed on one once and still regret it.