I am very Pleased with my Ruger MKII with 8 inch barrel and chambered in .25ACP!
Just not yet 'Snoopy' happy as I am still working on the Magazines To Fit it.
My Ruger "Single Eight" in .25ACP with a 10-5/8 inch Barrel is a little less happy as it looses about 2.1% off Factory Specified Velocity du eto cylinder gap venting.
.25ACP out of a 21 inch Barrel on a Single Shot rifle is relatively quiet but does have a Transonic Report.
Chev. William