Small base sizing die for 6BR/20BR

[potatohead]

I am trying to reload for a 20BR. I formed the brass from previously fired 6BR brass. I must have had the 6BR a little hot. The bases of most of the brass that chambers nice is .466" diameter and the bases I am having trouble with is .468" diameter. I am pretty sure I can squeeze the bases down using a small base die and wanted to see if someone here had one that I can borrow, rent or buy??? I have read I can use some normal FL dies for different cartridges that have a base of .463"-.466".....I do not have any of these though. Any help would be appreciated!!

 

[plinker625]

http://www.gunstop.com/Store/Reloading%20Dies/Redding/RED77201

 

[fguffey]

http://www.6mmbr.com/cartridgediagrams.html

potatohead, I believe it is fair to warn you, I come with baggage.

You say you may have fired the 6mmBR ‘a little hot’, I shoot at a bench, I am not a bench rest shooter, so I am curious how you measure the base of the case and where. The bottom .125 of the case is not sized, the bottom .125 is in the shell holder and, of course there is the radius on the bottom of the die. If I was trying to determine if I was shooting a little hot I would have measured the diameter of the case head below the case body before and after I fired it. The diameter of the case head above the extractor groove indicate the case head diameter is .470, not a problem but when determining ‘a little too hot’ the increase in diameter should show up there.

Then there is the case head thickness, no one measures, on 308W type cases the case head is .210 + or – a few, you want to size the base down to .463 to .466, I have small base dies but the 6mm BR is too large in diameter at the shoulder, meaning my small base dies will size the case body. Tools can be made to reduce the diameter of the case above the case head that would not look like a die, when using the tool caution should be exercise to avoid running the case through the tool, reducing the case head from .470 to .466 or less could destroy the integrity of the case head.

Again, measuring the case head with a dial caliper or micrometer is not perfect, some claim a bladed micrometer is ‘the only way’.

F. Guffey