The value of post chamber lapping

Bill Calfee

Gun Fool
The value of post chamber lapping


CYA friends:


Unless a schmidt does a post chamber lap, how quickly a new barrel comes in, is dependent on how quickly Mother Nature does her work.




What are the symptoms of a new barrel, in competition, that hasn't been post chamber lapped?



A shooter can simply be killing it, maybe for a full card, or more, then all of a sudden on the next card, despite the shooter's best efforts, he/she can't hit a 100....


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CYA friends:


There's a slow, creeping glaze, that builds up in the leade area of a rimfire barrel.


On a new barrel, that hasn't been post chamber lapped, this slow developing glaze, in the leade, may allow a shooter to kill it for a card or two, and then, even with the best bore cleaning regiment by the shooter, on the next card all hell will break loose...


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CYA friends, in today's competitive RFBR world of competition, a post chamber lapped barrel will save a bunch of heartaches........



There's nothing worse than completely dominating a big time RFBR field, then your rifle causing you to back up, and lose the match.


Post chamber lapping.....


It's mandatory to post chamber lap in today's RFBR world, unless you're in a position to give Mother Nature a chance to finish, both time wise and financially, the leade in your new build..




Your friend, Bill Calfee



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PS:


CYA friends, if one did no finishing of any kind to a rimfire leade, Mother Nature, given enough time, and enough rounds, will eventually produce a fluid transition from the chamber, through the leade and into the bore.....


Course the barrel might be shot out by that time.


No matter how one cuts a chamber, even with the sharpest tooling available, the leade will not have a fluid transition to the bore.

So someway the schmidt has to do something to provide that fluid transition....


The only way I could ever half way produce a fluid transition, without distorting the leade, was to use a hob......


And even then Mother Nature still had some work to do.


Some years ago my main reamer gave up.......


And my current reamer is not compatible with the hob for the old reamer.


So I pretty much had to start post chamber lapping all my builds.....


Course I don't worry about that now as I don't do builds any longer...


Oh yes, I could go in there and start polishing the leade and might produce a fluid transition.


But by the time I did so, the integrity of the leade would be completely gone.


The only way I know of to produce a fluid transition to the leade, without using a hob, is to do a post chamber lap.

 
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