Shootum, that is funny, but its sad but true!! There is alot of variation on these shells from one box to another. Alot!!! I set my 12 gauge 11-87 sps-t up last year with a jellyhead .660, and with the same load, can get around 320 on average. My last 8 shots were over 300, anything from 304-324. I found out what the lot number of those shells were, and bought a ton of boxes from midsouth shooters supply right after I found the combo in the same lot number. Actually I bought every box they had with that number. Lot numbers on boxes are big with hevi-13, there is a big difference between them. I just counted, I bought 19 boxes, Haha!! I won't ever have to buy another shell for the 12 gauge. Good luck to you BigHooks, it's more than likely not the gun or choke, it is the shell deviation. It can be drastic sometimes. See if the lot number was different. And shootum is really on the right track IMO.