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  #1  
Old 06-04-2008, 11:25 PM
1340 1340 is offline
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Default 20BR question

If someone says they have a 20BR, is it properly called a 20 Norma BR (Lapua?), as opposed to a 20 Rem BR? I'm confused. Is there much difference between the two? If ordering something would one have specify?
Thanks.

Last edited by 1340; 06-04-2008 at 11:28 PM.
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  #2  
Old 06-04-2008, 11:54 PM
1340 1340 is offline
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I did a bit of a search and found they are the same thing. It appears somebody's out to mess me up. Newbie trap!
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Old 06-05-2008, 04:19 AM
6BRBB 6BRBB is offline
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Agree its a little confusing. But you right; since Norma came out with their design if has fairly much stuck. i.e.

From:
http://www.6mmbr.com/6mmbr.html
"The 6mm BR that is most commonly used today is also called 6mm Norma BR, "6BR Norma", or just plain "6BR". Norma started with the 6mm Remington Benchrest case and made the neck longer and increased the base dimension slightly. Though Norma standardized the round, most people shoot Lapua brass, because of its superior quality and uniformity, not to mention lower cost."

Thus technically its a 20BR Norma. To be double-sure when ordering (e.g. reamer) I would state 20BR (based on Lapua Brass in 6mm BR Norma).

I hope I have not confused things further ....
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  #4  
Old 06-07-2008, 12:50 AM
GlennFromVA GlennFromVA is offline
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Default 6mm BR brass variations

There are three versions of the 6mm BR; Remington's original 6mm BR, the 6mm BR Remington, and the 6mm Norma BR. The case dimensions for all three of these cartridges are identical except for one dimension… the neck length on the original 6mm BR is .40" shorter. The specs on the Norma version are usually metric and do not translate exactly to inches. Norma changed only the throat dimensions for longer bullets, nothing on the case. Of course manufacturers have minimum and maximum tolerances and the brass can vary somewhat. I contacted Redding and they said the die dimensions for all three cases are the same.

Hope this helps, Glenn
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Old 06-07-2008, 02:04 AM
montdoug montdoug is offline
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Your absolutely right Glenn. My 40X 6BR had the shorter neck and I near got carpal tunnel trimming brass. What a curse ! I ended up with a Lyman power trimmer over it.
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  #6  
Old 06-07-2008, 04:18 PM
Randy Robinett Randy Robinett is offline
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Quote:
Originally Posted by GlennFromVA View Post
There are three versions of the 6mm BR; Remington's original 6mm BR, the 6mm BR Remington, and the 6mm Norma BR. The case dimensions for all three of these cartridges are identical except for one dimension… the neck length on the original 6mm BR is .40" shorter. The specs on the Norma version are usually metric and do not translate exactly to inches. Norma changed only the throat dimensions for longer bullets, nothing on the case. Of course manufacturers have minimum and maximum tolerances and the brass can vary somewhat. I contacted Redding and they said the die dimensions for all three cases are the same.

Hope this helps, Glenn
This (emboldened) is not exactly correct. There IS a significant difference in the web diameters of the brass produced by Lapua and Remington: the Remington brass will measure 0.463 - 0.464 just above the extractor groove, while the Lapua brass runs 0.469 to 0.04695". The latter is not a good match - it won't fit - for a chamber cut with a "Remington" dimensioned chamber, which will measure .467" - .468" at 0.200" ahead of the bolt-face. Conversely, using the Rem. brass in a [Lapua] .471" - .4715" chamber, which accommodates the Lapua brass, will result in rapid opening of the primer pockets , as the case head expands to fill the roughly 0.008" void.
In combination with a "properly" sized chamber-reamer, the Remington brass holds up quite well! In my experience, to avoid primary extraction problems, the difference between the chamber and the virgin brass should provide 0.0025" to 0.003" of clearance. These days, the best "fit" between brass, chamber, and re-size dies is apt to come when using a chamber bsaed upon the Lapua brass dimensions . . . It pays to know the reamer dimensions , and select brass and size-dies accordingly. RG

Last edited by Randy Robinett; 06-08-2008 at 12:15 AM.
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  #7  
Old 06-08-2008, 01:29 PM
GlennFromVA GlennFromVA is offline
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Default Randy, I came up with the same argument as you....

Hi Randy,

When investigating the 6BR I came up with the same argument as you, that the brass dimensions by different manufacturers varies. The response was that there are min and max dimensions on the specs, and manufacturers will vary in the production of the brass. In fact I was told that at least one manufacturer does not even meet the specs. For me the "bottom line" was when Redding told me there was basically no difference; their 6mm BR dies are the same for all versions. After all, when the brass is sized that determines the dimensions for the case. Neither the dimensions of new brass nor dimensions of the chamber matter... unless you had a set of dies made to match the chamber... and if that is the case you have a wildcat.

Looking into the history of the 6mm BR is confusing and will drive you nuts.

Best, Glenn
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