Flash hole size?

MIKE WISKEY

March 22, 2008 14:11

I'm working up loads/breaking in a .308 and am using a batch of brass with small flash holes (std. decaping pin is way to large). head stamp is 'RD 80 nato mark', I'll assume this is 'radway green' 7.62x51. any way what effect will the small flash hole have on load developement (higher/lower pressure-std dev.)? The best loads I've found so far are shooting .3's & .4's[:)].

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  ChetStafford

  March 22, 2008 14:48

  Mike,
  
  I don't know what effect the flah hole size will have but with groups in that size I would not worry about it[;)]
  
  Enjoy

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  shooter93

  March 22, 2008 16:16

  Over the years there have been a number of experiments run with smaller flash holes and brass made with them. most worked good but it takes a supreme rifle to see it. Black Powder cartridge shooters are now experimenting with tooling that sawges a uniform smaller flash hole. It appears to work but again it takes a very good rifle to notice it.

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  bpost

  March 22, 2008 16:57

  Hi Mike, Lapua 6MM BR brass uses a smaller .059 flash hole while some use larger. If you get a Sinclair or K&N flash hole uniformer you can eliminate one potential source of inconsistency. I have found that the smaller flash hole is easier on the primer pocket with full power loads. Lapua brass lasts a lot longer than the Remington brass does. The smaller flash hole, made more consistently could be why.

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  MIKE WISKEY

  March 23, 2008 05:21

  well it looks like we have an experiment in the making, once I settle on a load I'll go over several cases with my flash hole uniformer and compare with the smaller ones.

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  nononsense

  March 23, 2008 10:31

  MIKE WISKEY,
  
  I think it was back in the early 70's, Remington made a production run of .308 BR Basic brass for making target cartridge cases that all had the small flash holes. This idea was that the flame shape and length was more consistent to improve accuracy. When these cases were reduced in size to the BR case length, things began to look rosy for the target shooters. But when these same cases were necked to .308 and left at the .308 length, ignition became erratic. You can still find some of these cases for sale if you want to pay a premium for them.
  
  Lapua has asserted that the smaller capacity cases benefit from the small flash hole and makes not only the BR cases but has made several runs of the newer 6.5 x 47 Lapua cases with the 0.059" small hole. The problem is that even though the cartridges are known for better than average accuracy, it's difficult for the average shooters to note a significant improvement using the small flash hole. Lapua originally used the large flash hole in the 6.5 x 47 Lapua but after some extended testing in their labs and in with some U.S. shooters, decided to use the small flash hole instead.
  
  I like the idea of doing some comparative testing.
  
  Best.

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