Flattened primer mystery

[holejack1]

I have a Savage 12bvss in 308 that I bought used. It does not appear to have been fired much. I've tried Winchester 150, Federal 150, Remington 125 "reduced recoil", and surplus rounds. All except the Rem 125 flatten primers. Have only tried one hand load so far, 168 A-max over 40gr of RL15, and it flattened the primers too. Checked head space with go/no-go and it checks good. The gun is accurate shooting under an inch with Fed 150 and the A-max loads, but for the life of me I can't figure out what is causing the high pressure and flattened primers. Any rifle country gurus that might know what the problem is with this gun?

 

[Offfhand]

Those are not "flattened" primers. When you see are real flattened primer you'll know it.

 

[NCsmitty]

Welcome to THR, holejack1.

Your rifle may have a tight neck that is contributing to what appears to be slightly flattened primers.....or not. It's hard to tell in the pic if there is cratering around the firing pin.
I've seen factory ammo produce flattened primers many times in a variety of rifles, and it's usually not indicative of unsafe pressures. Range brass in 223 and 308 often show flattened primers.
Your A-Max load is a little puzzling as you're 5gr under max with the 168gr. Are you using Federal standard primers in the load?
I know primers are often hard to get in some areas, but benchrest primers and mag primers have thicker cups and may help with your problem.
I don't think that there is anything seriously wrong with your rifle, but if it continues to bother you, contact Savage with your concerns.
Let's see what other posters think.



NCsmitty

 

[Ridgerunner665]

Offhand is right...

What I see is an oversize firing pin hole in the bolt face (the mild cratering) and modestly warm factory ammo (likely using a faster burning powder).

Those primers ain't flat...

 

[Steve Marshall]

Check your headspace. Every case shows the primer out of the primer pocket. If anything, I'd say your pressure is on the low side.

 

[Vern Humphrey]

Have only tried one hand load so far, 168 A-max over 40gr of RL15, and it flattened the primers too.

According to the Hodgedon manual, that load is 2 grains below the starting load.

Primers backing out but not flattening (and these primers are not flattened) is a sign of low pressure. When the firing pin hits the primer, the cartridge goes forward a bit. On primer ignition, the primer backs out a bit. As pressure builds up, the head is slammed back against the bolt face, re-seating the primer. Low pressure rounds may not re-seat, resulting in primers like those in your pictures.

That crater edge, most visible in the third case from the right in your picture might be a sign of a too-large firing pin hole. Or it could be a too-soft primer.

 

[Ridgerunner665]

I'm not seeing the backed out primers...

 

[alsaqr]

Those are not "flattened" primers. When you see are real flattened primer you'll know it.

I agree, those are not flattened primers.

 

[375shooter]

Those are not "flattened" primers. When you see are real flattened primer you'll know it.

I agree with the others. According to the photo the primers are not flattened more than normal. They indicate standard pressures. Even the slight cratering is not a concern.

 

[Bwana John]

Primers backing out but not flattening (and these primers are not flattened) is a sign of low pressure.

+1, primers not "flattened"

 

[Uncle Mike]

Nothing wrong with that rifle! Those primers look A-OK from here!

 

[holejack1]

Well thanks for the input. I had been wondering about the primers backing out myself, but don't see how it's possible when the head space checks good. However, I do feel better about shooting it with some more knowledgeable folks saying there is nothing wrong.

 

[wilkersk]

Here's some flattened primers. Also, notice the deformation in the base of these cartridges: