Canalure vs throat


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86thecat
November 27, 2007, 04:59 AM
Reloading for a Mod 70 375 H&H which has taken a dislike to most spitzers. Having much better accuracy with round nose. Checking length to lands for Hornady 300gn btsp's I would have to seat about .250" longer than max OAL (canalure 1/4" beyond case). Checked various bullets and have found distance from canalure to point which bullet is land diameter varies from .030 to .200". Am I missing something here? Do bullets normally vary this much in distance to canalure to ogive? The rifle has 500+ rounds through it so the throat may be opening up a little but I don't expect good accuracy with a .200" jump.

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jmorris
November 27, 2007, 10:22 AM
I routinely load bullets out further than the cannelure (with no crimp) for the same reason you mention. I do so in a single shot bolt action with great results. If you were to do that in your 375 H&H with a full magazine, I would worry about the bullets moving around during recoil. You could load them one at a time to see if they make any noticeable difference, if so invest in one of these http://www.buffaloarms.com/browse.cfm/2,350.htm and put the cannelure exactly where you want it.

rcmodel
November 27, 2007, 02:09 PM
Am I missing something here? Do bullets normally vary this much in distance to cannelure to ogive?Yes they do.
The factory puts the cannelure on bullets to make the loaded round a standard OAL length to fit box magazines, and prevent bullet set-back from recoil. There is no consideration given to what effect bullet design or ogive shape has in relation to the leade or rifling when figuring cannelure placement.

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rcmodel

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