Oh, don't be discouraged!
I have an SBE II also.
You can buy a +2 mag extension for $110, it will let the gun hold 1 extra round, 2 if they are 2 3/4. This will let your mag hold 5 2 3/4" or 4 3" or 3.5".
You can also hold one in the barrel.
The next step is to "float a fourth on the feed ramp" Google it and read the how to steps by tucker 301. A bit of devcon puddy and you can legally hold an extra shell because you magazine still only holds five.
Add it up and you have 5 in the mag, 1 on the fee ramp, and 1 in the pipe. 7 total for 2 3/4".
When you can throw 7 up in the air and get'em all, PM me...have fun shootin!