HELP! Do I have a headspace or excess pressure problem?

[TheEngineer]

I recently purchased a used Remington 700 in 7mm-08. I have been examining my fired brass and have noticed an alarming trend, they're all stretching more than I would have anticipated! See the links, at the case head you can see the bulge and deformation below it. My measurements show an avg. max diametric growth of .006" at the bulge at the head and .008 at the shoulder, when compared to an unfired round. I'm also finding approx .004" of OAL growth (2.025" - 2.029).

http://i331.photobucket.com/albums/l480/cmmgguy/IMG_1681.jpg

http://i331.photobucket.com/albums/l480/cmmgguy/IMG_1680.jpg

Unfired:
.465" head
.450" shoulder

Fired
.471" head
.458" shoulder

My primers (see second photo) also seemed to be flattened and the firing pin indentation is cratered. This rifle was next to new when I bought it and these are factory loads (Hornady 139gr. SST). Who knows how long it was sitting on the shelf before I bought it though... When compared with the reloading data, my "fired" dimensions are close to the spec dimensions shown.

I've also fired some Prvi Partisan 140gr. PSP which has similar "fired" dimensions (I don't have any of it unfired) but does not show the "bulge" at the head like the Hornady brass does. The Prvi does have a similar primer flattening and cratered firing pin indentation.

I'm new to reloading and have been reading the Hornady and Spear manuals as I want to get into it (I don't own any equipment yet). So I broke out the calipers and starting measuring. I understand some growth will occur (and can be beneficial to a reload) but this seems like a lot based on what the manuals have stated.

Is this just the cases "seating" in the true dimensions of my particular chamber? If so why do the primers look like they're trying to blow out? Am I freaking out over nothing? I wouldn't be so alarmed were it not for the non-uniform bulge at the case head on the Hornadys. I don't care what anyone says, as a practitioner of engineering and materials science I know that that is not normal and it would seem consistent with poor casting/machining of the case or too hot of a powder load since the Prvi rounds don't do that.

Anyway, I look to you wise CalGunners for your advice, thanks in advance.

-Jason

[ar15barrels]

Is this just the cases "seating" in the true dimensions of my particular chamber?

Yes.

Diameters have nothing to do with headspace.

[Pthfndr]

Normal. Plus your primers are no where near flat. Plenty of roundness on the edge of the primer.

[30Cal]

I assume you don't have a chronograph but where do your loads stand with respect to what the manual says? If you're not in the "Near Max" or greater neighborhood, you're probably fine.

Primers aren't the best sign of pressure, but when they start to get really flat or crater, I take a closer look at what I'm doing.

It's tough to say from the photos, but those don't look worrisome to me, but if you're outside of published load data, then you're on your own.

[30Cal]

I assume you don't have a chronograph but where do your loads stand with respect to what the manual says? If you're not in the "Near Max" or greater neighborhood, you're probably fine.

Primers aren't the best sign of pressure, but when they start to get really flat or crater, I take a closer look at what I'm doing.

It's tough to say from the photos, but those don't look worrisome to me, but if you're outside of published load data, then you're on your own.

[rayra]

Looks 'normal' to me. It's a high pressure load, anyway. That primer flattening is not severe.
The difference in 'bulge' could be nothing more than difference in the brass itself or case wall thickness near the web / base / head. Or it could be a pressure difference in the brands. No way to tell.

I'd be more interested to see what the casing looks like after a full-length re-sizing with a standard die.

Additionally, I don't see any signs of the primer backing out, which is sometimes an indicator of excessive headspace (and too-high pressures, as well).

Lastly, I'd compare the rim to shoulder length on an unfired case to a fired case. That'll give you as good an indication of an excessive headspace indication as the aspects you are trying to use.

And lastly your reported OL measurement is still .006 UNDER spec. That certainly seems to preclude a headspace issue (even if headspace is measured to the shoulder and not the case mouth).

And I didn't see any mention of any difficulty working the bolt after firing.

I think you are seeing problems where there aren't any. But kudos for studying up.

[tankerman]

Chamber could be a bit over sized. What gun were you shooting?

[TheEngineer]

Thanks for all the responses, I think the bulge in the Hornady brass is what concerned me most. After consulting a few reloading manuals I am just going to scrap that brass. I wasn't aware that case expansion and elongation occurred in such a magnitude though, especially in comparing to the "specs" the various manuals list for dimensions.

Thanks again-

-Jason

[rksimple]

FWIW, primer cratering can also have a lot to do with firing pin protrusion and the firing pin channel size. Doesn't necessarily mean too much pressure. As far as the other concerns, things don't seem too bad. Taking some measurements with a case comparator would give some indication as to headspace woes.

[lazuris]

7m-08 is normally formed from .308 brass by neck sizing down to 7mil. Are these factory 7m-08 or did you form them your self?

[TheEngineer]

Factory Hornady loads, 139gr. SST. Do you think it has something to do with resizing one of their .308 cases? I would expect a manufacturer of that scale to have a separate line or process for 7mm-08 in spite of it's obscurity.

On that note, I have been looking at whether I am going to full-length resize or neck size (after fire-forming the first ones of course...). Given the heritage of the 7mm-08 case, would I be better off full-length resizing? I'm using it in a bolt-action Rem 700 as mentioned before and accuracy is of the higher concerns, so I am leaning for neck-sizing.

Thanks again!

[rayra]

Thanks for all the responses, I think the bulge in the Hornady brass is what concerned me most. After consulting a few reloading manuals I am just going to scrap that brass. I wasn't aware that case expansion and elongation occurred in such a magnitude though, especially in comparing to the "specs" the various manuals list for dimensions.

Thanks again-

-Jason

If this is the first firing of this brass there really shouldn't be any concern. The bulge is not strictly an indication of failure, but more likely an indication of a lack of chamber support in that region.

You might even consider dissecting a casing to allay your concerns.

Really no reason yet to discard valuable casings.