In my stash of goodies, I have a set of cylinder hones for revolver cylinders, that have been used before to super clean & leave a cross hatched pattern to a pistols chamber bore.
I have .355"/38/357/9mm IF you can't get that chamber to your liking.
Bought at Brownell's decades ago to fix a rough S&W 940 9mms revolver cylinder.
The more I see problems with those FILTHY barrels I would steer clear of them.
Hope they work out for you guys...
I don't think I will be buying one of those slides, and building a 4" Shield Upper

BUT?
The slides are drying up quickly.
4 left on eBay today & price went UP to $70
SMITH & WESSON M&P 2.0 9 SHIELD OPTIC READY SLIDE PC PRO C.O.R.E (SMI3007879 | eBay
11 on CDNN's website @ $59.99 + $9.99 S&H
SMITH & WESSON M&P 9 SHIELD OPTIC READY SLIDE
Back to watching AEW Wrestling
Gary/Hk