Tracy:
Just in case you are wondering, I've been shooting 2 3/4" cartridges in 2 1/2" 12-bore guns for decades. I check forcing cone allowance and keep velocities below 1200 fps with 7/8 oz. or 1 oz, loads. I've never had a problem, hit everything I lead properly, and have never had a problem with "skived" cartridge hulls like AA or Reminton STS.

Best, Kensal