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Posted: 6/13/2016 8:59:26 PM EDT
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I have been shooting Greek surplus 3006 for a few months now and reloading it as well. I have mostly early 70s cans which have worked out fine.
I was out at the range today and I picked up a ton of year 78 Greek brass from other shooters. When I went to remove the primer crimps with the tool I noticed the extractor groove is longer than on my early 70s casings. My question is, does this variation in extraction grove affect headspace as the actual body of the case is a tad shorter than my other cases? They still have the correct shoulder length as the only difference is the thinner rim and longer extraction groove. I am shooting this from a Garand. 
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depth/width of extractor groove is irrelevant. And while there is slightly less case body length (due to the larger extractor groove) it has absolutely no bearing whatsoever on headspace. The '06 headspaces on the shoulder, so the only dimension that matters is the base to shoulder length. Heck, you could machine a case with NO extractor groove, and from a headspace perspective there would be no difference.
I suppose that you have every so slightly less case body surface area. In a entirely esoteric and theoretical sense, its possible that you might have a marginally very so slightly higher bolt thrust due to somewhat less surface area of the case expanding and "gripping" the chamber at the moment of firing. Then again, I suspect that theory just might be voodoo and speculation too. Load em up and fire em. |
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During the CMP Advanced Maintenance Class, John (if I remember name correctly) specifically said Greek surplus cases are well made for reloading. Long lasting.
I loaded a case a couple months ago with no issues. I don't run a ton of 30-06 (yet). I plan to run the garand and 03A4urgery more over the summer. |
The cases just have the 308 extractor channel relief channel to them.
As for why, could be that the loading machines where just set up this way from a 308 run and left that way, or could be that they where using firearms that needed the longer extractor rim relief cuts instead. Considering that old Greek surplus ball has the normal 30-06 case extractor channels. 
Given the date of the later ammo,, could have been that they could not get Garand replacement extractor's, where using M-14 extractors in the Garand bolts, and the reason for the 308 extractor cuts in the 30-06 ammo instead. https://www.ar15.com/archive/topic.html?b=6&f=6&t=247990 Garand on the left, early M-14 middle, and late M-14 on the right. 
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