[Sisco]

Okay.
The brass test: two of five cylinders the brass from the GP fit fine, dropped right to the rim, the other three cylinders had to be pushed the last 1/16" or so. (.38 spcl, didn't have any unsized .357)
The bullet test: four of five cylinders the bullet would pass through with slight effort, some less than others. The fifth cylinder the bullet had to be forced through. As another test I dropped the jacketed bullet in from the back then pushed it all the way through with a pencil. Same thing, 4 of them dropped on through with very little effort the 5th one requrired considerable force to get it through.
Tried the same thing with the GP, they all went through with ease but then again the GP's had a couple thousand rounds through it.
I'm going to take the cylinder to work tomorrow and have a machinist check the inside diameter of all 5 cylinders.
Call Ruger?
Another note. I had 6 rounds of .357 lead SWC's that I fired though the SP, can't remember the data on the load, but they ejected ok.