That ammo is bad. Not sure why, but it should NOT be deformed the way you describe.
Toss that stuff and buy some new. Being unable to chamber a round when you and yours are on the line is NOT a good thing.
Sometimes, if shotshells are kept a very long time in a full magazine, the mag spring pressure will deform them. Doesn't happen very often, but it does happen.
Or, those rounds may have been 'over-filled' with buffering material between the shot pellets, and when the shell was crimped, it pushed the pellets into the walls of the shell a bit too much. This doesn't happen very often, either, but I have seen it a few times in my 30+ years of shooting.
I do sort of very vaguely remember about 20 years back a box of #4 shot that was supposed to be 1-1/8th OZ. They were bulged and lumpy the way you describe. I cut open a couple, weighed the shot charges, and they were 1-3/8 OZ. I don't remember the brand now, but when I contacted the maker with the lot number, they sent me 2 boxes.