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Ejector mark on 3oo RUM need advice

 
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  #8  
Old 09-05-2012, 02:49 AM
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Join Date: Aug 2011
Location: Townsend MT
Posts: 70
Re: Ejector mark on 3oo RUM need advice

I'm with everyone else on distance to the lands bein the culprit. Are you loading out of an 8 pound can of powder or a bunch of different 1lber's that could be from different lots??? Lot numbers on your powder is the only other thing I would look at if its not all from the same can.
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  #9  
Old 09-05-2012, 07:51 PM
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Join Date: Nov 2011
Posts: 20
Re: Ejector mark on 3oo RUM need advice

I'm using same powder. I'm confused now with the distance to the lands. My Nosler reloading manual says to set bullet off of lands between .015 and .03 inches. I'm at .024. Does this not apply to a 300 RUM.
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  #10  
Old 09-06-2012, 06:09 AM
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Re: Ejector mark on 3oo RUM need advice

Folks shooting 30 caliber magnums in competition with max safe (normal) loads with bullets seated out to touch the lands have been getting excellent accuracy since the 1950's. I've no idea what the internal ballistics are with bullets so seated, but pressure's fine and accuracy has equaled what the long range benchresters get these days.

Ejector hole marks in case heads typically indicate pressure's too high. Cartridge brass starts to extrude into holes in the bolt face at about 65,000 to 70,000 CUP (80,000 to 89,000 PSI). Bore obstructions, tight bore and groove diameters for the bullet or the wrong powder type or charge weight are common causes. Regardless of the cause, it you see ejector hole marks on the case head, something's causing it. We all get to choose our own safety margins to shoot in.

It's best to remove anything you put in the bore after cleaning it before you shoot it.

There was an article in the American Rifleman many years ago on the pressure difference between bullet seating about 1/10th inch off the lands compared to touching them. It was only about 2,000 to 3,000 CUP difference in the .30-06 cartridge they used. Here's an example:

http://www.noslerreloading.com/phpBB...hp?f=4&t=16847

Note the two far right bars indicate the bullet was seated .001" and .021" long and was set back that far when chambered. And no pressure difference between bullets seated .019" off the lands and .001" long to push back that far.

Shame on those who put two different pressure measuring systems' charts together. The top one with bars is acutally CUP numbers and the bottom one with the curve is PSI. But they do show pretty well that pressure goes up a bit when a given load's bullet touches the lands when its fired.
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  #11  
Old 09-06-2012, 07:23 AM
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Join Date: May 2012
Location: N.D.
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Re: Ejector mark on 3oo RUM need advice

If you really want to run just a few thousandths off the rifling, go for it. But don't expect to not have to drop a grain or three to run safely if you are getting ejector marks at current charges. I do run my 300 win .010" off the lands with one load, but it fits the mag even being a browning, and the load has been shot hundreds of times in all temps. without a hint of over-pressure. My 300 rum gets treated differently, partly because it's throated long enough that I'd be single loading, partly because it uses slower powder and a lot of it with some very tough bullets that like a run to the lands.
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  #12  
Old 09-06-2012, 04:46 PM
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Join Date: Jul 2007
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Re: Ejector mark on 3oo RUM need advice

welcome to the "non-stock' .300 rum, each and every custom/semi-custom is different. load for YOUR rifle and forget all the "do this/try this/mine only likes" BS.
some of mine will shoot 180's, some 168's, i don't shoot over 180's, cause i have bigger rifles if i need more range/kill'em power, and i wont tell you what the loads are, cause your's will NOT be the same.
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