7-08 Loaded Neck Diameter

[mdesign]

I am working on a 7-08 build and trying to make some decisions on the chamber reamer. As a qualifier, I have been talking this back and forth with Dave Kiff but I wanted to run this by you all for your thoughts.

The neck diameter on a 7mm match chamber is .316" and SAMMI shows the neck diameter of a loaded 7-08 cartridge to be .315. Problem is, I can find no brass with a neck wall thick enough to come close to that and I would like to run it a little tighter to minimize resizing.

WW, Remmy, Federal (Lapua doesn't make it I guess) all have neck wall thickness of about .013-.0135 making the neck diameter of a loaded round measure right a .311 or .004 below SAMMI. I found some Norma brass that was 15 yrs old and it measured .014.

Kind of thinking of running a .314 dia neck on my reamer for this build but wondered what some of you were seeing for loaded neck diameter on your 7-08's or 7mm cartridges? Looks like you could run just about anything out there without having to turn necks to make it work.

 

[USMCj]

Re: 7-08 Loaded Neck Diameter

Easy, buy some Lapua 308 brass (I would do that regardless for 7/08 as I hate any brass not made by Lapua) and use a full length 7/08 sizer to size it down to 7/08. You will not only have made the most consistant 7/08 brass, but necking down from 308 to 7mm will thicken the neck wall thickness, at this point you can choose to neck turn to just clean up the neck and get the thickness you desire, or you can just run with it if its the thickness you were after.

 

[mdesign]

Re: 7-08 Loaded Neck Diameter

Thought about that but not sure how well it would work. Going that path sort of locks me into thicker necks but might be worth it in the long run if accuracy end up being better.

 

[bohem]

Re: 7-08 Loaded Neck Diameter

If you're going to the expense of running a neck turn, match chamber then USMCj's advise is absolutely spot on.

My 7x57 and 7 SAUM cases have necks that run (unturned) at .316 and for the SAUM I turn them to .314

The 7x57 I only know from measuring out of curiosity, it's a 1908 DOM Argentine Mauser, I feed it bulk grade handloads and don't worry about it.