Headspace Question - New brass larger than fired?

Bidwell

Lil-Rokslider
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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!
 
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 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
 
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.
 
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 :)
 
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 :)
Wow... This explains a lot! Appreciate the story. I don't really mind it necessarily, this rifle shoots really well, it was just a head scratcher! Not really sure if this is worth the hsssle or not, but I'm starting to consider using cerrosafe to make a mold of the chamber and ship it off to a die manufacturer to get a custom die for it. From what I've heard, it's not super pricey to do. Mostly I'm just curious what the exact chamber dimensions are.

Edit: I don't have much of a sample size to compare, but I'm wondering if the min spec chamber is helping this rifle shoot more consistently. Seems to barely matter when I change bullets, powder types and charges. Shoots all about the same. The barrel is pretty thin and even when it gets hot it doesn't seem to affect poi. I still like to wait 3-5 min between shots at the range but just an observation.
 
Wow... This explains a lot! Appreciate the story. I don't really mind it necessarily, this rifle shoots really well, it was just a head scratcher! Not really sure if this is worth the hsssle or not, but I'm starting to consider using cerrosafe to make a mold of the chamber and ship it off to a die manufacturer to get a custom die for it. From what I've heard, it's not super pricey to do. Mostly I'm just curious what the exact chamber dimensions are.

Edit: I don't have much of a sample size to compare, but I'm wondering if the min spec chamber is helping this rifle shoot more consistently. Seems to barely matter when I change bullets, powder types and charges. Shoots all about the same. The barrel is pretty thin and even when it gets hot it doesn't seem to affect poi. I still like to wait 3-5 between shots at the range but just an observation.
That juice ain’t worth the squeeze on an inexpensive factory rifle, IMO. Just size the brass to work in your chamber and roll with it.
 
That juice ain’t worth the squeeze on an inexpensive factory rifle, IMO. Just size the brass to work in your chamber and roll with it.
Thanks, yeah I'm sure it isn't. Out of curiosity, has anyone created a custom die just so they can sort of build in their desired shoulder bump within the die? Of course, brass bounce back won't be consistent every resize but maybe it would reduce time spent getting your die configured. I'm still a little confused about what side effects there might be when your die dimensions are larger than you chamber. I get that you can adjust your die further down into the press to get proper shoulder bump, but what about side wall dimensions?
 
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!
That does make for a good head scratcher.

If you’ve fired 4 times and the brass is shrinking, I’d bet lunch without knowing anything else those are not anywhere near max pressure loads. Starting loads can shrink when pressure in the brass is enough to hold the brass in place as it’s expanded outward, (then the shoulder springs back), but not enough to stretch out the case head.

Also, as the firing pin slams into the primer it pounds the entire case into the shoulder of the chamber which also can reduce the length. This is easy enough to check by dry firing into the same case, measuring each time.

The other common cause is measurement errors if the caliper isn’t zeroed because it’s a few extra steps to remove the measuring gizmo and put it back on, and it never really shrank.

A third way measurements change in weird ways is how the measuring gizmo reads the outside of the shoulder and after pressure molds the entire shoulder to the chamber in length and width, then springs back, the originally measured portion may read a little shorter.
 
Thanks, yeah I'm sure it isn't. Out of curiosity, has anyone created a custom die just so they can sort of build in their desired shoulder bump within the die? Of course, brass bounce back won't be consistent every resize but maybe it would reduce time spent getting your die configured. I'm still a little confused about what side effects there might be when your die dimensions are larger than you chamber. I get that you can adjust your die further down into the press to get proper shoulder bump, but what about side wall dimensions?
If you were a Benchrest competitor with an expensive custom rifle, a custom die might make sense. As it stands, it makes little sense.

Again, you simply have a measurement issue and just need to take measurements with the proper tools (caliper and comparator) to resize your cases properly. That also applies to sidewall dimensions. Without taking careful measurements, you cannot ascertain much.

You are getting way too far ahead of yourself. Start at the start. Measure twice, cut once.
 
That does make for a good head scratcher.

If you’ve fired 4 times and the brass is shrinking, I’d bet lunch without knowing anything else those are not anywhere near max pressure loads. Starting loads can shrink when pressure in the brass is enough to hold the brass in place as it’s expanded outward, (then the shoulder springs back), but not enough to stretch out the case head.

Also, as the firing pin slams into the primer it pounds the entire case into the shoulder of the chamber which also can reduce the length. This is easy enough to check by dry firing into the same case, measuring each time.

The other common cause is measurement errors if the caliper isn’t zeroed because it’s a few extra steps to remove the measuring gizmo and put it back on, and it never really shrank.

A third way measurements change in weird ways is how the measuring gizmo reads the outside of the shoulder and after pressure molds the entire shoulder to the chamber in length and width, then springs back, the originally measured portion may read a little shorter.
Thanks! Yep, I'm using the minimum load suggested by Barnes, 46.2m1 grains of Ramshot Tac on 130 grain TTSX. It shoots well and a little over 3000 fps so never really needed to push it more. Never considered that this may actually cause my case length to shrink!

When you said "Also, as the firing pin slams into the primer it pounds the entire case into the shoulder of the chamber which also can reduce the length. This is easy enough to check by dry firing into the same case, measuring each time." Does this mean I should try chambering my fired case and dry fire a few times to see if the headspace shrinks?
 
Thanks! Yep, I'm using the minimum load suggested by Barnes, 46.2m1 grains of Ramshot Tac on 130 grain TTSX. It shoots well and a little over 3000 fps so never really needed to push it more. Never considered that this may actually cause my case length to shrink!

When you said "Also, as the firing pin slams into the primer it pounds the entire case into the shoulder of the chamber which also can reduce the length. This is easy enough to check by dry firing into the same case, measuring each time." Does this mean I should try chambering my fired case and dry fire a few times to see if the headspace shrinks?
What you have is explained by the starting loads so I wouldn’t worry about the effect of the firing pin fall, but if you’re curious it might be fun to check. Lapua brass is pretty hard compared to other brands, so the firing pin may not make much of a difference.

With light loads sometimes it can be odd/interesting to find the case was pushed forward so the shoulder hits the chamber and the primer has backed out of the pocket enough to reach the bolt face. With a straight edge across the base of the cartridge if it rocks on the primer at all, that’s what it’s from.

🙂
 
There’s nothing wrong with shrinking brass as long as the accuracy is ok. One summer I ran 1,000 light loads through a rifle and the brass kept shrinking to the point it was concerning to see the primers out of the pocket so far, so every 5 or so reloads I’d run a full power load through them to stretch them back closer to the bolt face. I don’t remember how many reloads the brass went through before being tossed out, but they seemed to last almost indefinitely.
 
What you have is explained by the starting loads so I wouldn’t worry about the effect of the firing pin fall, but if you’re curious it might be fun to check. Lapua brass is pretty hard compared to other brands, so the firing pin may not make much of a difference.

With light loads sometimes it can be odd/interesting to find the case was pushed forward so the shoulder hits the chamber and the primer has backed out of the pocket enough to reach the bolt face. With a straight edge across the base of the cartridge if it rocks on the primer at all, that’s what it’s from.

🙂
I'll definitely try the primer test to see if it's popping out at all. Good to know!
 
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