I just looked at my lifter with 2 7/8" chambers( serial# 20690). It does not have that sharp step/shoulder in the chamber that my 2 5/8" guns have. In my 2 5/8" 10 gauge lifters I almost exclusively shoot brass black powder shell. Even RST shells in 2 5/8" at 1100fps and 1 1/8oz. produce more recoil than I would like in these short chambered lifters. In my most recent 10 gauge lifter which is on the light side and has 2 5/8” chambers, the above RST load was too much in my opinion. Here is the thread with that gun:
http://parkerguns.org/forums/showthread.php?t=30193
I am going to experiment with a 1oz. smokeless load an see how that works in a 2 5/8” gun. I think that would be 1 oz and 18grains of Red Dot(from memory so please double check if interested).
Back to Wayne’s original question. I might try a few lighter loads, like a square load of 2 3/4 drams of 2f and 1 1/8oz of shot or go down to 2 1/2drams of 2f and an 1oz to start slow. Track of the Wolf does sell the 2 7/8” brass shells(as well as 2 5/8”).
I think the variable I don’t know the answer to is the influence of the step/shoulder instead of a forcing cone with shorter shells. I don’t have a gun like that that has 2 7/8” chambers. I would think the fiber wads would be more forgiving. However, you could not go wrong by getting the 2 7/8” brass shells.