.308 lapua to 7-08 I know its been covered many a time but...

[lurcher]

Out here in New Zealand Norma 7-08 brass is half as expensive again as lapua .308 per 100, and lapua .308 is just slightly cheaper per 100 than win and rem 7-08 brass.

I just bought some .308 lapua to convert to 7-08. I intended to skim the necks to improve clearance (I plan to go for about 4 thou clearance as this is a hunting rifle) so I ran a few pieces through a hornady FL die with the expander removed to check chamber fit before sizing the whole box.

I was surprised to see that the case mouths were very slightly flared after the sizing operation, what causes this?

I checked the brass length and after sizing it was 2.015 or thereabouts. According to measurements taken with a sinclair chamber plug gauge my chamber is 2.060 long.

At what point do cases become to short and what is the issue here? I know that carbon will build up in the chamber and it is hard to remove. As long as I am careful to clean the chamber with carbon remover and a wire brush, and check it with the plug gauge prior to switching back to longer brass are there any other issues?

In the past I have always trimmed new brass. Due to the length issue I was considering just chamfering and polishing the ends of cases with some scotchbrite pad to avoid making them any shorter. Should I trim to square them/even them up?

 

[jasonf]

The Norma stuff is more than twice as expensive as Lapua over the ditch, so I am taking the same approach as you.

The case mouths flare out on my cases after running through a FLS die too, but then straighten up when I run a Sinclair 7mm expander mandrel through them prior to turning. I think the flaring is caused by spring back in the freshly annealed brass.

My chamber is long too (2.070")' but I don't worry too much about it because I only plan on using the Lapua brass. Your plan of thorough cleaning before going to longer brass seems sound.

I haven't trimmed my cases, but have been measuring them, and after first firing they ended up pretty even.

If I was doing it again, I would probably use the Lapua 260 brass, just because it is a bit longer.

That said, I am getting excellent accuracy and velocity from my 308 based cases.

Cheers, Jason.