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Unaccetable varianace in COAL with Berger VLDs?

 
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  #1  
Old 02-05-2014, 04:51 PM
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Unaccetable varianace in COAL with Berger VLDs?

When I went to work up a new load for a .260AI with the 130 Berger VLDs, my COALs were all over the place. I typically measure the chamber to get the COAL and then set my first round for about .005" jump, take that round and measure base to ogive and go off that, and measure every 5 rounds or so confirm a constant measurement. When I did that today, I had cases with as much as .015" difference. I know each bullet from the ogive to the tip will be inconsistent, but I have never experienced that much variation from round to round. I typically like less than .003" variance, is that about right? Could it be that I was loading VLDs with a regular seating stem? I load Bergers in other cartridges and love them, but I also have the VLD stem in those. Thanks for the input.
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  #2  
Old 02-05-2014, 07:35 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

All we could do is guess and there can be many causes.
Sounds like you have a lot of investigating to do.

Your cartridge base to ogive(CBTO) should not vary ~3thou. I would stop reloading and fix this.
You should measure every one and every one should measure the same. Then load ammo.
Do you have a bullet puller?
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  #3  
Old 02-05-2014, 08:48 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

Is there any chance you are using a compressed powder charge?
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Old 02-05-2014, 08:52 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

I want to make sure I have this right.

Are you getting the inconsistent reading using a bullet comparator from case head to O-give?

Or the OAL from case head to bullet tip?

Jeff
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  #5  
Old 02-06-2014, 01:44 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

I get some degree of variance but I don't use a VLD seater stem. I'm shooting a 6.5x284 and a 300 rum. I usually get about .005 to .008 at the most in OAL. I've been thinking about drilling the stem out so the bullet will seat on the ogive instead of the nose. I went shooting the other day and I had some that repeated velocities and some the would be 10 to 14 FPS off. I was load testing in groups of 3 shots. This made me wonder if the seating could be causing this but who knows. Also I did not clean between the 3 shots so it could be a number of things. Even with this degree of variance my 6.5 shoots .5moa. So I have not been to apt to mess with it.
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Old 02-06-2014, 02:19 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

As Mikecr said your CBTO should not be varying much...The COAL you are measuring is normal for Bergers as of late....but the base to ogive should be fairly consistent in spite of the huge variances in actual bullet length...The distance to the lands will remain very close regardless of the COAL... And yes .015 length difference is not an uncommon within the same bullet lot...My guess is that your "jump" is probably fairly consistent and that your COALS are normal for your "lot" of bullets...Your seating stem is probably OK for your Bergers unless some meplats are actually hitting the tip....Other concerns as mentioned earlier are compressed loading and seating pressures and seating technique that all affect COAL and CBTO..

However Bergers as of late are very different animals when there is a lot change...So if you can afford to buy a 1000 or more at a time you could be better off....I have seen .015 off in CBTO with a lot change and .050 thou in length...I can't afford to be buying 1000 at a time and can't afford to burn out any more barrels working up a new load every time I get a new "lot" of the same bullet...So for that reason my plan is not to buy any more Bergers until they learn to change dies more frequently...There are other bullets out there that remain way more consistent from lot to lot.....

Good Luck,
Randy
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  #7  
Old 02-06-2014, 03:18 PM
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Re: Unaccetable varianace in COAL with Berger VLDs?

Thank you all for your input. To be clear, I started with my Sinclair seating depth gauge, I took that measurement and made my first round and then measured the case head to ogive. I set my seater die with a regular stem, made my second round, it was within .002" of the first, so I made 5 more and checked the 6th, it was.015" off base to ogive and also COAL. I went back and checked each round and set each one at a time, with having to pull some. It is a slightly compressed load, but I was thinking the problem might be a combination of bullet inconsistencies and and the regular stem hitting above the ogive.
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