Do primer pockets stretch? .308 Fed GMM

[wayno1]

Just annealed some .308 Fed GMM cases fire for 4th time.
Trying to clean pockets with Sinclair primer pocket tool. It always took out the primer residue before and left the bottom of the pocket shiny. now not touching the residue at all.
Did the pockets lengthen? I can measure the depth with my Sinclair calipers. Shows .1285
What should the max be?

thanks!

Wayne

 

[gunsnjeeps]

Yes they can. Generally they stretch until they won't hold a primer. I don't have a depth measurement handy.

 

[armorpl8chikn]

Yup. Sho nuff do.

 

[arnie19]

I don't know about 308 but 30-06 Federal brass is real bad about loose primer pockets after a couple firings .

 

[FLIGHT762]

I can measure the depth with my Sinclair calipers. Shows .1285
What should the max be?

thanks!

Wayne

For large rifle primer pockets, Minimum depth is .125" Maximum depth is .132". You're within specification. Primer pockets will stretch in width, usually due to high pressure loads. High pressure loads will stretch the pockets out to where the brass will need to be scrapped. If you're stretching pockets with 2-3 loads, it's likely your loads are too hot. You need to reduce the powder charge. I can get 8-10 loads out of Federal brass with moderate loads.

 

[40xs]

I can only get about 3 good loadings out of winchester brass (match 1000yd loads) before the primers almost "fall" in. I've been very cautious about looking for flow back and have been lucky not to have issues up to three loadings, but I'm not chancing any additional firings out of them. I get a few more firings out of Lapua, as one would expect! I suspect the reason I have yet to have issues might be due to me using Federal 210 M primers. they are soft and tend to "fill up" the pocket upon firing and "seal off" the excess deminsions. I would rather not experience issues during a match is my reasoning for holding to three firings with Winchester. Plus, My loads are on the warm side.

 

[wayno1]

wow.... hot?
I am loading 3-4 x fired FC GMM cases with 168gr SMK, 43.0 grains of Varget, OAL 2.82", Fed BR primer.
Over Chrono showing 2625 FPS with Magentospeed Chrono which is a muzzle velocity.
Unlocking bolt to eject cartridge is a little stiff, but it's a little stiff chambering the rounds since I am Lee neck Crimping vs resizing.
using Sinclair shoulder gauge, showing 1.613-1.614.
Cases may just be stretching. Primers seat with a little push. They don't just 'slide in'.
Will be using these until they are not holing primer well then move to the LAke City Match cases I bought.

Am open to opinions on this and thanks to all.
Wayne

 

[wayno1]

Thank for first answer! I think it will work out. Iam within specs.

 

[wayno1]

Thanks, as I mentioned in another post my loads:
.308 Fed GMM 3-4x fired brass, 43.0 gr Varget, Fed 210 M primers, OAL 2.82, bullet 168 gr SMK.
Lee crimp on neck vs resize.
Shoulder showing 1.1613-4 on the fired brass.

 

[leadbullet]

43gr of varget with a 168 is not hot, 48 gr of varget with a 155 is. no matter what brand of brass or load recipe, sooner or later the primer pocket will loosen up.

 

[poison123]

Thanks, as I mentioned in another post my loads:
.308 Fed GMM 3-4x fired brass, 43.0 gr Varget, Fed 210 M primers, OAL 2.82, bullet 168 gr SMK.
Lee crimp on neck vs resize.
Shoulder showing 1.1613-4 on the fired brass.

Wait are you saying your just crimping the necks and not resizing at all?

 

[wayno1]

Actually it's a Lee Precision 308 Collet Die

 

[wayno1]

And yes, not resizing or bumping shoulder back until the bolt starts getting a little stiff to close, then bump back about .002 and go from there.

 

[UNCIVILIZED]

If memory serves, there are tools for primer pocket reswaging. It's likely worth a search... on here, and with a few different vendors, like Dillon & Midway. If you find a tool which does the job, it be appreciated if you post said info.

 

[wayno1]

Primer Pocket Cleaner | Sinclair Intl

Here are more than a few for cleaning. If you want to 'swage' a primer pocket to remove a crimp, Dillon has a great one.