Headspace Question - New brass larger than fired?

[Bidwell]

Hunting season is coming up so i wanted to get some new brass. Before getting started, I was curious to compare the headspace between my new 308 lapua brass vs my 4 times fired lapua brass (before fl resizing again).

I fully expected my 4 times fired brass to have a larger base to datum measurement number than my new brass. I was surprised to see that my new brass was .0015 to .002 larger, tested on several samples. Any ideas on how that could happen? Pretty sure my cases should be larger after expanding in the rifle chamber. Is it just manufacturing tolerances? To confirm, my 4 times fired brass hasnt been full length resized since its firing. Also, i tested my new brass in a headspace/case length gauge and its fully in saami spec. Rifle is howa superlite. Im wondering if my chamber size is on the lower end of saami spec.

Thanks!

 

[WeiserBucks]

New brass is larger than your chamber sounds like. Size it and move on.

 

[SDHNTR]

I bet your bolt close was stiff(er).

The new brass was probably on the long end and your chamber on the short end of spec. You probably had more expansion at the base or throughout the case body as that’s where the material would have moved.

 

[Bidwell]

I bet your bolt close was stiff(er).

The new brass was probably on the long end and your chamber on the short end of spec. You probably had more expansion at the base or throughout the case body as that’s where the material would have moved.

I haven't fired the new brass yet, but on my last range session I had a few rounds where I couldn't close the bolt, this was with 3x fired brass. I use a rock chucker supreme and I typically full length resize by just touching the die to the shell holder. Never had any issues before and I get pretty good accuracy 1 to 1.5 moa with 7 shot groups. I'm wondering if I should do an extra 1/8 turn inwards for my full length resizing now to push the shoulder back a smidge. Still newish to reloading so any advice welcome

 

[SDHNTR]

I haven't fired the new brass yet, but on my last range session I had a few rounds where I couldn't close the bolt, this was with 3x fired brass. I use a rock chucker supreme and I typically full length resize by just touching the die to the shell holder. Never had any issues before and I get pretty good accuracy 1 to 1.5 moa with 7 shot groups. I'm wondering if I should do an extra 1/8 turn inwards for my full length resizing now to push the shoulder back a smidge. Still newish to reloading so any advice welcome

You need to take real measurements. The turn the die in 1/8 turn method as stated on the instructions if far too imprecise. Get a set of headspace comparators and measure with your calipers. But yes, you should be bumping your shoulders back .002” ish from fully fireformed.

 

[Vern400]

I had the same exact experience with a brand new Howa 308 last fall. It came to me for load development. Nothing special just a good shooting load. I loaded up 10 cartridges with "Top Brass" brand once fired LC brass. Never had a problem with that before. I've never had to size it before, and it claims to be fully reconditioned.
Six out of 10 were too tight on headspace. Several wouldn't fit at all.

So I resized it the normal way, using the dies set for my other rifles. NOPE. Wouldn't fit. So I adjusted the sizing die all the way down to a light cam -over.
They are RCBS dies, but not the small base dies.
All the empty cartridges chambered okay, but I could tell there was zero clearance to the chamber.

I switched over to Federal brass because it's thinner and a little softer than lake City. That works fine. There was a little less spring back in the cases then there was with the LC.

The Howa 308 new rifle I loaded for definitely had a minimum spec chamber. And headspace. It was also one of the ones that had the sticky bolt situation and it was pretty frustrating. It's a fairly common situation that's well known, and unfortunately I had to learn all about it also.

That being said, the rifle shoots fine. I would challenge their 1 MOA claim just slightly. But before I did that I'd want to shoot Federal gold medal match with 168 Sierra game Kings in it. That's the gold standard for pretty much everything shoots it well.

Good news is the final solution was to use commercial brass, not military brass, and there's no adjusting for headspace dude! You ram that sucker into the die as far as you can get it and if you're lucky you'll have 0.001 or 0.002 headspace clearance. It works.

Maybe your rifle in the one I worked on was made the same day