20 gauge 2 1/2 inch loads

[Bruce Day]

Mr Davis, Win and Rem 20ga expanded shells are 2 9/16 out of the box, not 2 3/4 as the box cover states. The shells meet the 2 3/4" SAAMI specification tolerance. The length designation refers to the maximum length of shot cartridges in that box, and not to actual length. The extra 1/16 won't make any practical difference in pressure. We get this question a lot and the solution is to actually measure an expanded shell and see for yourself.

I see no real reason to cut back AA or STS shells back 1/16 " , and I'm not sure that would be possible. Even if they were truly 2 3/4", the difference in chamber pressure is only a few hundred pounds, and that would not critical to any gun having acceptable wall thickness, when as you are probably aware, a common 20ga service load pressure is 10,000 psi.

When we teach shot gunning, this issue frequently arises. Some are convinced and have heard tales about dangerous overpressures from shooting longer shells in short chambered guns. While that can be true in extreme examples, the Sherman Bell series of articles in DGJ put that tired issue to rest for those who read the research. We often find gunners who have shot for many years who have never actually measured a shot cartridge and are surprised and learn when they do.

Many photos showing this issue have been posted here and are available using the search function.