Recently I learned something new concerning gunsmithing and I'd like to share it with you.
We as individuals get caught up in our day to day activities, in our ruts and we get fat dumb and happy. After chambering numerous barrels I sent my Range Rods back to PTG for inspection and re-certification. 99% of the barrels I work on are Krieger, always have been, probably always will be. My first Range Rod was a 6mm and it dated back to April 2007 when I started doing my own BR Rifle work. I found that over time with numerous barrels and residual lapping compound left in those barrels my rods had become scratched, all except the .30 cal rod that is. The 30 cal rod was spotless and has been in Krieger and Rock Barrels only.
The TIR of the rods were at .0000" but one of the scratches on my .284 Rod was .0002" deep. The problem was this, I indicated a barrel in to .0002", pulled the rod out and re-inserted. It was at .0003" Breech and .0006" at the end of the rod. Dikem proved the setup was good and I got 100% clean up with my facing cut but, I needed to know why the rod acted as it did.
Dave Kiff worked on this for me and during our conversation I checked a .270 Range Rod still in my possession that had been in one barrel, it had scratches on it that could barley be felt with my finger nail. The culprit had been found. Lapping compound left on the minor diameter of the bore. You see, if a scratch is .0002" deep and th erod is removed then reinserted the scratch locks up at a different point, maybe on top or on bottom. This will change your indicator reading as it did mine.
The Range Rods are hardened to around 50 Rockwell per Kiff and he told me the only thing that could do that would be lapping compound. I share this with you to let you know this, clean your barrels prior to indicating/machining and use a light coat of Marvel Mystery Oil on your Range Rods. Rifles I’ve built & owned have all shot lights out. Had I not tried an experiment I read about on BR Central I wouldn’t be typing this now.
Just thought I'd share. If we don’t try different things from time to time or try to maintain the very tightest tolerances we can and double checking ourselves as we go, we stop learning the "Whys & How Comes" and stay in our ruts. I want to continue learning as I think you do, that’s the reason for this post, good luck to you and remember, think outside of the box.
We as individuals get caught up in our day to day activities, in our ruts and we get fat dumb and happy. After chambering numerous barrels I sent my Range Rods back to PTG for inspection and re-certification. 99% of the barrels I work on are Krieger, always have been, probably always will be. My first Range Rod was a 6mm and it dated back to April 2007 when I started doing my own BR Rifle work. I found that over time with numerous barrels and residual lapping compound left in those barrels my rods had become scratched, all except the .30 cal rod that is. The 30 cal rod was spotless and has been in Krieger and Rock Barrels only.
The TIR of the rods were at .0000" but one of the scratches on my .284 Rod was .0002" deep. The problem was this, I indicated a barrel in to .0002", pulled the rod out and re-inserted. It was at .0003" Breech and .0006" at the end of the rod. Dikem proved the setup was good and I got 100% clean up with my facing cut but, I needed to know why the rod acted as it did.
Dave Kiff worked on this for me and during our conversation I checked a .270 Range Rod still in my possession that had been in one barrel, it had scratches on it that could barley be felt with my finger nail. The culprit had been found. Lapping compound left on the minor diameter of the bore. You see, if a scratch is .0002" deep and th erod is removed then reinserted the scratch locks up at a different point, maybe on top or on bottom. This will change your indicator reading as it did mine.
The Range Rods are hardened to around 50 Rockwell per Kiff and he told me the only thing that could do that would be lapping compound. I share this with you to let you know this, clean your barrels prior to indicating/machining and use a light coat of Marvel Mystery Oil on your Range Rods. Rifles I’ve built & owned have all shot lights out. Had I not tried an experiment I read about on BR Central I wouldn’t be typing this now.
Just thought I'd share. If we don’t try different things from time to time or try to maintain the very tightest tolerances we can and double checking ourselves as we go, we stop learning the "Whys & How Comes" and stay in our ruts. I want to continue learning as I think you do, that’s the reason for this post, good luck to you and remember, think outside of the box.
