Author Topic: Rifling cutting into hard bullets  (Read 1046 times)

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Offline stubshaft

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Rifling cutting into hard bullets
« on: February 09, 2011, 10:02:46 PM »
Hey Veral,
Just wanted to pick your brain on one of the newer "theories" I have been hearing recently.  It goes something like this:

"If your bullet is too hard (over 23BHN) or contains too much antimony.  The the rifling will cut into the bullet instead of displacing metal and it will leave "curls" of metal in the barrel".

Hard for me to get a handle on this one.  I have shot virtually every type of bullet made from old Harvey pro-tex-bores to Kynoch steel solids and have never experienced anything that would lead me to this type of conclusion. 

Your thots please
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Offline Veral

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Re: Rifling cutting into hard bullets
« Reply #1 on: February 10, 2011, 05:40:05 PM »
  Theories always seem to have holes in them.

  When there are ribbons of lead hanging off the rifling, (always the leading edge of coarse) it is because the lubricant wasn't up to preventing leading.                PERIOD.   
Veral Smith

Offline stubshaft

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Re: Rifling cutting into hard bullets
« Reply #2 on: February 10, 2011, 06:04:53 PM »
Thanks for taking the time to reply.  I just wanted validation, too many fairy tales and no practical application.
Joe
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Offline Veral

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Re: Rifling cutting into hard bullets
« Reply #3 on: February 23, 2011, 07:00:37 PM »
  I'm sorry about the shortness of my angry answer.  I tend to get a little bump up  in blood pressure whenever I have to answer for the wisdom of  ignorant interlopers who pretend to be LBT.

  My answer was correct, but there are variables which prevent lube from working.   If the bore is extremely rough, or just a little rough when shooting plainbase, specifically on the leading edges of the rifling, this roughness can act like a file and strip lead away.  When some lead gets stripped away, or wiped back into the grooves because of excess drag against the bearing along the rifling edge, a space forms on the non driving side of the rifling, which allows lube to squirt forward, losing the hydraulic lube pressure required for good high pressure load performance.   Sometimes softer bullets will partially solve the problem, by reducing leading, but it it does, you'll have a very narrow pressure window to work with, i.e. a very precise powder load will probably be required.  And accuracy will never come up to what could be if things were right, meaning the bore were lapped or a quality lubricant was used.        Regarding this last statement.   If the problem is happening with any lube beside LBT, give one of ours a try.  It normally fixes the problem if the rifling edges aren't  extremely rough.   
Veral Smith