Just thought this was interesting. I have the S2O, but could not bring myself to have it cut for an optic. So I bought a new S2 slide and sent it off to CGW for an optic cut and their barrel bushing. When I got it back recently, the barrel was a bit difficult to insert/remove. Doable, but I have to apply a little force through the ejection port to get it out. As a side question for anyone that has had the CGW bushing installed, is it normal to have to force it a little?
I've only shot it a couple of times now and decided to try the stock S2O barrel (polished barrel) when I was cleaning it, just to test the fit. It slips into place with the CGW bushing easier than the S2 barrel (black barrel). I was a little surprised by that. Maybe it's the black coating on the S2 barrel? Both barrels lock up tight in either slide. And there is no detectable slop in the barrel/bushing of either. The S2O barrel has a few thousand rounds through it, so that might be part of it as well.
I have not shot the S2O barrel in the S2 slide yet, but will soon. I'm sure it'll work well, but curious if it will impact accuracy (which I know is a hard thing to fairly judge w/o a rest, etc).