I did a careful measurement of the cylinder throats on my 629-4 MG today using an expanding ball tool and a micrometer. It seems that they are .4293 give or take a tenth or so. My bore groove slugs out at .4296-.4299. It would appear that I need to have the throats reamed out a bit. I have seen a link here to a fellow who calls himself Cylindersmith, has anyone used his services and is he still doing it? Another question. When I shoot .430 jacketed XTP bullets out of this gun what is it doing to the cylinder and to the pressures getting through the throat? If I have the throats reamed out to .4305 will the gun have problems shooting .429 jacketed bullets accurately?