Form 308 brass from 30-06

[thespecialist]

Wait a minute, let me get my fire suit and explain why I want to try this.


My SPS Tactical has one of Remingtons notoriously big chambers and is extremely generous in the neck area. My fired cases measure .341", meaning my Winchester brass is expanding .010" in the neck during firing as loaded rounds give me a neck diameter of .331". I'd like to see less expansion than that, mainly to help brass life but I think it might also tighten up my groups a bit more too.

Just for grins I removed my expander from my 308 FL die and ran a piece of 30-06 brass through it, made one funky looking piece of brass. I rough trimmed to length with the dremel, finished it with the Gracey, then ran the brass through my neck die with the expander in place. What came out was a piece of 308 (dimensionally) brass with .004" neck tension and an O.D. of .338". I know when I load a bullet it's going to expand to .341-.342" so I'll need to neck turn for clearance. Question is, how much do I need to turn it down? If I have a loaded neck diameter of .337-.338" will that give enough expansion for proper bullet release, or do I need to go down to around .336"?


Second question, who makes the best tool for doing this quickly(ish) without dropping a small fortune? I'll only be doing this with my precision loads, so manual tools will suffice.


All these measurements were taken with Winchester brass, both the 308 and 30-06.

 

[hondakilla98]

Re: Form 308 brass from 30-06

Interesting question. Tagged for later.

 

[5R Milspec]

Re: Form 308 brass from 30-06

at .338 your looking at .003.If I'm not wrong thats just right for a tight neck chambering.and if thats the case I would turn the necks to just clean them up.for the first fireing.then you should be OK.

maybe some one that nows more or has been in your shoes before will post soon.but want to know what happens and what else is said.

 

[armorpl8chikn]

Re: Form 308 brass from 30-06

Your climb will not be worth the view. First of all You will need to ream the inside of the neck, likely several times as you use this brass. You will not see greater brass life and you will have headaches you can't imagine. There is no logical reason to do what you have proposed. There is nothing especially large about your chamber for a factory rifle either. I just measured a few 06 cases I have accumulated from several different rifles. They measure from .343" down to .339", my custom '06 fired brass measures .337" at the neck. All the brass in that box came from rifles that would do better than 1MOA. If doing this radical reform and ream, trim, turn etc would turn your gun from 1.5 MOA to 1/2 MOA this might be a worthwhile adventure....but it won't. You are wasting your time that would be better spent shooting.
Your chamber is not sloppy but rather fairly normal. They make them that way so that they will chamber all brands of ammo with ease. I have seen one tight chambered rifle in the dozens of factory rigs I have owned and yes it is a shooter and an exceptional example of a factory rifle.
I tried this trick once reforming 308win to 243win. I was convinced they would somehow be more accurate. After hours upon hours of reaming and trimming, reforming, neck turning I had a few perfect cases and a gun that shot no better.

 

[thespecialist]

Re: Form 308 brass from 30-06

That's what I wanted to know, whether there would really be any real benefit to it or not. Thanks armor