Shotshell Bulges

[Mr. 16 gauge]

How old is your data, and how old are your cases?

In my experience, one of the things I've found is that over the years shotshell makers change the structure of their shotshells. I have some older 16 gauge Federal hulls & some of the newer ones made recently. If you ask Federal, they are the same hull, and are made by the same process.....but the plastic on the older hulls is stiffer/thicker, and in some cases loads better.

I was working on developing a buffered bismuth & a buffered turkey load. I had problems with the cases bulging as you described on some of the hulls, but not on others. Closer inspection revealed that the shells that bulged were of recent manufacture; the ones that loaded up O.K. were older hulls or those manufactured originally for steel shot.

Just my experience, FWIW....