This may be out in the left field some, but I have a M1 TAC with the 18.5" barrel and it will function without any problems using the 1oz load of FEDERAL Game-Shok. A 3 1/4 Dram EQ load that produces 1200 FPS in by Beretta 391 with a 28" barrel. Several people have used the gun with that shell/load and no problems. Short barrel, light 1oz load and 1200 fps (in a 28" barrel) and no problems in a new gun during the first 150 rounds. Don't expect it to develope problems as the gun wears in.
From the above, I would expect an SBEII to operate well with a 1 oz load. Maybe I have missed something though!
BIll