I have run the Wolf Polyformance in 9mm and 45 acp and never had a problem. Just a side note.... fired up my o2/accl torch on an empty case and could not get the coating to melt or run. Case was red hot and nothing came off so at least with the Wolf brand, varnish buildup should not be a problem, Can't comment on the Tula or the other brands. I was surprised how accurate the .45 was!