308 necked down to 7mm-08

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g-manz35

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I've necked down 40 cases from 308 to 7mm-08. They are once fired range brass that I simply run through a FL sizer. they don't chamber easily but they do chamber with a little resistance when the bolt is lowered. So I've done a lot of reading on the subject and a lot of people say not to neck down because of the increase neck thickness. I've seated a bullet in them and they seem to chamber just as easily.

So they SAMMI spec for the neck thickness is .315. If I measure all my rounds and they are at or below .315 I should have no concerns right? I have necked down several 30-06 to 270 win with no problems but that is a different rifle. What do you guys think?

George
 
You should have no issues what-so-ever, I used a bunch of military 308 for my son's 260 and had adequate bullet release without thinning necks. Military brass is much heavier and noted for thicker necks than commercial brass, so I can not see this being the problem with your resized brass. I suspect you just didn't get your die down quite far enough on your initial reform/resize cycle.
 
Generally when I do this, I full length size in the original cartridge die first, before necking down. So, I would use a .308 Winchester FL die first, and then neck down. Doing this has given me trouble free cases for my 7mm-08.
 
As long as they chamber I'll fire form them and I should be good to go after that. It's a new rifle so I will be doing a barrel break in/sighting in so I can easilly put the 40 rounds through it that I have resized. I think I will try and neck size a couple the second go round and see how they are. If they are still tight I will run them through the FL sizer again. I'm pretty sure they are a bit tight where the shoulder is formed from the what used to be the neck of the 308.

Thanks for all the replies.

George
 
358 said:
You may want to trim these.The excess brass has to go somewhere. Mark
Click to expand...

Actually the case length ends up short of the 2.025 - 2.035. they are anywhere from 2.018 to 2.023 for the 40 cases I've sized so far because the 308 case is only 2.015 in length to begin with.

George
 
I am no where near trimming any of the cases I am sized down to 7-08 after a few firings, I did however turn the neck a bit just to true them up a hair.

g-manz35 said:
Actually the case length ends up short of the 2.025 - 2.035. they are anywhere from 2.018 to 2.023 for the 40 cases I've sized so far because the 308 case is only 2.015 in length to begin with.

George
Click to expand...
 
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