At the time of my writing, none had failed English proof -- and that is your warranty. The owner must be smart enough to shoot the shells the gun was proofed for. The guns are proofed under standard CIP pressures per the particular gauge. They are not lined.
Jim, there's your "warranty" information. People will stick 3" shells in guns clearly marked 2 3/4". Not much the manufacturer can do about that, other than to mark his gun properly. In this country, of course, we've now reached the point--due to litigation, I expect--that you'll see many guns marked "Read owner's manual before using." Well, as the kids used to say . . . duh.
You must've missed the Remington recall of either 1100's or 870's due to barrel failures. I can't remember which, nor when it happened, but someone else will I'm sure. Assuming the Baker barrel failure was due to either an obstruction or some sort of critical reloading error, such an incident might just as easily rupture a modern steel barrel in the same manner you see in the Baker photos. One of our "teaching tools" in our hunter education classes is a blown up side by side, about the same place as the Baker . . . only this one has steel barrels.
Ed's comment about mismarked ammunition deserves further discussion. I have a box of 00 buck 12ga high brass Winchester shells, came to me straight from Winchester. Only thing is, the box is marked "Winchester AA Light Target Load"--and it was one of a flat of AA's, the only difference being all the other boxes really DID have the proper contents. (I called Winchester and told them they might want to check that particular lot.) If I, like Ed, had been using those shells in a dark duck blind, then I too might've simply fumbled open the box and stuck them in the gun. An error more obvious than the one Ed encountered, and at least quite clear in the light of day. (I certainly would've caught the problem before I shot a round of skeet with them!) So such things do happen, but I think they're pretty rare.
