So I recently got some 125 blue bullets. Id heard that they were a bit undersized at .355 and accuracy reports were varied. I've slugged rifle barrels before, but not slugged my CZ barrel. So... I decided to try something new and hopefully easier. I've never heard of anyone else doing this and looking for opinions on why or why not to do it this way.
With no powder on the bench, and only this single bullet, I sized and primed a case and seated the bullet, intentionally creating a squib. Took this squib round directly to the gun and then fired it outside in safe direction and got the expected puff, removed the barrel and pounded it out. There was my slug - it had definite markings for the rifling - ready to measure. It was dark and not well lit so I had a tough time getting calipers in the right spots on the lands and grooves but from what I could tell it was swaged down by the barrel a bit on both the lands and grooves.
cons - The only con I can see with this method is that the throat or leade may be shot out and a little bigger than the muzzle of the barrel.
pro - much easier than slugging the entire barrel. you slug the barrel with the actual bullet you will be using, not some super soft lead that may have some spring back and not give proper measurements.