I just took a look at the Gunbroker ad. This is EXACTLY the kind of ad I would avoid at all costs.
First, he specifies the item is to be sold "AS IS. No refunds or exchanges." This position is indefensible when dealing with used firearms. Any, and I mean ANY honest dealer will not only agree to an inspection period, he'll insist on it to protect himself.
The first rule about buying guns on the internet:
NEVER, EVER BUY A GUN UNSEEN WITHOUT A MINIMUM 3 DAY INSPECTION PERIOD WITH A MONEY BACK NO-QUESTIONS-ASKED GUARANTEE. NEVER.
Second, he states the gun looks (emphasis is mine) new and unfired. If you're buying the gun for appearance only, that's just fine. But if you want it to actually work, the word "looks" is a big red flag; the fact that it only looks good means, by default, that it doesn't work good.
Finally, the caliber is mis-stated. There's no excuse for that. I don't care how many guns you claim you've sold, if you don't know the caliber, you don't know what you're talking about. Doc, you may have sold things you didn't know anything about, but you admitted it up front. This guy not only didn't admit it, he still claims he's an expert.
The A+ rating and 312 positive feedbacks is the only plus in the ad. I have to wonder how he earned them given the obvious clues to his dishonesty in the ad.
There are plenty of reasons in this ad to stay away from this seller. In the end, myankee took advantage of Sabot and should take the gun back, but frankly I'm hard pressed to say Sabot wasn't warned.