A few years back(prior to 2006) I was almost exclusively using one Button rifle barrel maker. Had customers breaking national and international records every month. The velocities were 100-200 fps faster and the extreme spreads were single digit. Then all of a sudden, I had five barrels in a row, that were slow, shot fliers and the extreme spreads were in the 50-60 fps range. I contacted the barrel maker and he said nothing had changed and his barrels were still the best on the market. Between my customers and myself we spent thousands of dollars in ammunition and loading time trying to find a load. I set all five barrels back and re-crowned them and still poor results. The barrel maker denied having any problems, with materials and his process. I changed barrel makers and replaced all five barrels at my expense. All five rifles went to shooting one ragged hole (sub .25 MOA). I spoke to several other gunsmiths and they were experiencing the same issues. After talking to another great gunsmith about the problem he recommended that I slug the barrels since nothing was visible with a bore scope. Boy were my eyes opened. All five barrels had multiple tight and loose spots between the throat and muzzle. I know there were a couple of years barrel makers were having trouble getting good steel. But I also found out the barrel maker I was formerly using had lost his three best employees, who were previously hand lapping all his barrels. I was told he was going to the labor pool and getting day help to lap barrels. Lapping barrels is a hands on learned skill I also had noticed that the diameters marked on the barrels were never what I was pin gauging them at. I purchased 20 pins in .0001" increments (10 above and 10 below normal bore diameters) for .219", .220", .221",.222",.223",.224" .236", .237", .260", .277", .284", .297",.298", .299",.300". I found between .0002" and .0005" differences in what was marked on the barrels. Years after the problems I ended up meeting several of the employees who had worked for the previous barrel maker. They told me the barrel maker did not even have a way to accurately measure barrels, that he just put on them what he thought the bores would be based on the reamed hole diameter and the button dimensions and what would be normal spring back.
I now use barrels made by a very reputable barrel maker. He knows what the bores are based on measurements after the bores are final lapped. He encouraged me to slug my barrels to verify what I was getting. I had a second barrel maker that I was using that had some problems, they realized they had a problem and replaced the defective barrels without question. The defect was easily identified by slugging their barrels. I will be the first to say America is blessed with some great barrel makers. We also have some that are not so great. My recommendation is for people looking for a new barrel to do their homework and look at what the top shooters are using. Talk with your gunsmith, does he offer any guarantee. With quality gunsmith work and good barrels it is not hard to get a rifle to shoot .5 MOA.
With a good bore scope you can see some anomalies, ie: carbon, copper, fire cracking, tool marks, etc. Slugging a barrel works by feel, things you can't generally see.
Nat Lambeth
