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The primary use of lapping is to remove small imperfections (tool marks, etc) from the bore after rifling. Some makers lap the bore after final reaming to make sure the tops of the lands have no radial tool marks. After rifling the barrel they lap the grooves with a lead lap and abrasive compound. Other barrel makers just lap the whole interior in one shot after rifling. All this is done in order to eliminate, as much as possible, tearing of the bullet jacket during passage and subsequent metal fouling of the bore. By keeping metal fouling to a minimum, accuracy of the barrel is enhanced and more rounds can be fired with acceptable accuracy between cleanings. I don't know what "triple lapping" is unless they are using three different grades of abrasive compound. When you, as some makers suggest, clean after each shot for ten shots, etc, etc, to break in a new barrel, it is not done to increase accuracy except coincidentally. What you are doing is burnishing the throat and leade area, until those portions of the barrel are worn in and the tendency to metal foul is minimized there. None of these measures are necessary if your object is to hit a paper plate at twenty five yards. However, if the object is to clean the six hundred and thousand yard ranges with high "X" counts, they are definitely helpful. Hope this helps, I used to make rifle barrels and so am somewhat familiar with the procedures. Cheers and good shooting, Phil |
It does both and it does not decrease the life of the barrel. |
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I don't think it will improve accuracy. It certainly won't make a bad barrel into a great barrel. It will however help a great barrel shoot well for longer before it fouls up and then starts opening up due to the fouling. Lapping definitely helps with cleaning and in my opinion aids in break in(or not really even requiring break in) thanks to those imperfections having been removed already. Difference in cleaning something like a factory Remington 700 "coppermine" barrel and a lapped match grade barrel is like night and day. The lapped barrel proves to be more consistent over the long haul as well. But I highly doubt that lapping my Remington 700's factory barrel is going to tighten it's groups, maybe help it maintain what groups it does shoot for a higher round count before cleaning but that is it. |
And that is known as "improved accuracy" No , it won't help your Rem 700 because if it was aggressively lapped the bore would now be oversized. a true lapped match barrel starts out at .005 to .001 undersized. A skilled lapp job opens the bore up to a more consistent diameter because tight spots can be felt while lapping. There is no debate to lapped barrels improving accuracy. This is why most match barrels are lapped. The only reason for not lapping is cost. |
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