One of the things to consider before you lengthen the forcing cones on any shotgun is to pattern it first with the loads that you intend to shoot.

I've got a 28" 21 that was built in 1941 with 3inch chambers, .732 bores, and .037 choke in both barrels. It has several non standard features that the original customer wanted in a field model. I sent to Cody when I got the firearm and they sent me not only a letter but also copies of the final inspection report and factory build sheet. The paper answered a bunch of questions I had about how original the shotgun.

Parris

GOOD SHOOTING! Parris George