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bwalters99
Advanced Member



945 Posts

Posted - Mar 17 2014 :  07:15:37  Show Profile Send bwalters99 a Private Message  Reply with Quote
Hey Everyone...

I picked up a box of Berger .243 (6mm) 90g. BTHP's just to shoot to get some of my Lapua cases fire formed to the chamber.

I weight sorted them, and found the whole box of 100 only had a spread of .3g. (89.9 - 90.1) which I was pretty jazzed about. I thought that Berger's QC must be really tight, or maybe I just got a good batch.

Just for grinnies I decided to measure them all for just bearing length. The spread here was a bit more than weight separation ranging from my measured lengths using two comparators of .470 - .475, the majority was at .471.

I wanted to see how far off the measured bearing lengths were from Berger's specs.

First, I looked at Berger's "Bullets Quick Reference Sheet", and then looked at the specs in Bryan Litz's Applied Ballistics Book.

Both references were way off from what I measured. The quick reference sheet showed .322, and Litz's Book showed .304.

Either my method of measuring is way off, or I just don't know..





As far as my ammo log goes, I'll use my measurements, but it sure is confusing as to why there doesn't seem to be a consistent guide for bullet specs...

curly
Moderator



Canada
3232 Posts

Posted - Mar 17 2014 :  09:39:13  Show Profile Send curly a Private Message  Reply with Quote
Perhaps the "method" of measurement being used by the manufacturer differs from yours....as well as the measuring equipment being used.....Just my two pennies...

Curly
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Dom
Moderator



USA
2201 Posts

Posted - Mar 17 2014 :  10:08:27  Show Profile Send Dom a Private Message  Reply with Quote
Could be just the method of measurement. Looks like the BT is inside the .24 to the ogive, and the end of the bullet is in the other .24 up to the ogive. Or am I missing something? In any case, the variance you have is not too shabby.

-------- There are those who only reload so they can shoot, and then there are those who only shoot so they can reload. I belong to the first group. Dom
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bwalters99
Advanced Member



945 Posts

Posted - Mar 17 2014 :  12:27:01  Show Profile Send bwalters99 a Private Message  Reply with Quote
Curly & Dom....

Yeah.. you guys are probably right... either different equipment or method of measurement is being used... Hard telling... not knowing..

I'll just have to trust that even though I don't possess (or can afford) scales that measure to 1/100 of a grain, or calipers that measure to .0001, that it'll be close enough for my reloading needs.

Still striving for near perfection though...

Oh.. and Dom.... I rechecked to make sure that the BT end was seated right up to the shank.. It was....

Just the reflection from the flash in the picture I think...

Edited by - bwalters99 on Mar 17 2014 12:31:29
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Dom
Moderator



USA
2201 Posts

Posted - Mar 18 2014 :  01:22:44  Show Profile Send Dom a Private Message  Reply with Quote
quote:
bwalters99: . . . Still striving for near perfection though...

Bruce, that will sure keep you off the streets

-------- There are those who only reload so they can shoot, and then there are those who only shoot so they can reload. I belong to the first group. Dom
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bwalters99
Advanced Member



945 Posts

Posted - Mar 26 2014 :  09:07:59  Show Profile Send bwalters99 a Private Message  Reply with Quote
Just a follow-up to the OP, and the answer I received back from Berger Bullets.

quote:
Subject: FW: Bearing Surface/Length



Hello Bruce,



Thank you for getting with us at Berger Bullets. You are not doing anything wrong. When you check your bullets with the same two mechanical bullet comparators, you are not actually sitting on the exact “break over” reference points. You are hitting a “reference” point that may, or may not, coincide with these locations. Our chart has been updated since Bryan first wrote the book, so what you are seeing is a correction to our data. We use an optical comparator to measure the bearing surface, and this is what is showing the discrepancy from your mechanical “reference” measurements. However, for your reloading needs, for your rifle, your reference measurements will be valid for your personal needs for reloading for your rifle. Please do not hesitate to get back with us if we can be of further assistance for you.





Kind Regards,

Berger Bullets Technical Support Team


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Got-R-Did
Advanced Member



1075 Posts

Posted - Mar 26 2014 :  12:45:53  Show Profile Send Got-R-Did a Private Message  Reply with Quote
Are these to fired in a custom rifle or one from the Factory line? Likewise, are you using a Redding or other competition seating die? Have you done comparisons of other "match" bullets in your inventory?
Got-R-Did.
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bwalters99
Advanced Member



945 Posts

Posted - Mar 26 2014 :  13:44:45  Show Profile Send bwalters99 a Private Message  Reply with Quote
Got-R-Did....

These particular rounds are just going into a stock Weatherby Vanguard that I've had for 15 years, and maybe put a box of rounds through. I never appreciated the value of having a .243, but am just now beginning to realize that it may have been an error in judgment.

And yes... I use a Redding Competition Seating Die for all my rifle loads. I only load for .223, .308, and now starting in on the .243, but I have the Redding Seating Dies for all...
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Got-R-Did
Advanced Member



1075 Posts

Posted - Mar 27 2014 :  13:56:31  Show Profile Send Got-R-Did a Private Message  Reply with Quote
Roger That on the Weatherby. As good as these rifles shoot, I doubt you will be able to isolate any accuracy anomalies to the few thousandths variance in the Berger bullets. I look forward to any results you post with this rifle.
Got-R-Did.
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