Chilean Mauser ruptured primers

[GREASY357]

Long time no post, I took my beautiful Chilean Mauser out to shoot some groups and noticed a few primers ruptured. Shooting S&B 140 grain 7mm Mauser. I'm guessing this is a pressure issue?

[pacrat]

Cannot really tell from those pics. Straight down and lots of glare. Try backing up a bit, and place camera at 45* angle to give an oblique view of the bases.

That will allow determining if cups have flattened notably.

From what can be seen. I see no bolt face imprinting. Or primer cup extruding.

Likely just soft cups. Or a bit much FP protrusion.

[baih777]

Turn off the flash
Need to.see the primers off to the left.

[GREASY357]

I'll take some more pictures after work. The primer under the "p" in the photobucket watermark is clearly ruptured if you can see that/ zoom. Maybe need to turn down the firing pin a couple thousandths

[GREASY357]

Here's a pic of the rifle btw, vortex 2-7 scout setup (no bubba required). The irons are about 12" high at 100 yards haha

[ar15barrels]

Sometimes it's a primer problem and then the gas from the piercing will erode the tip of the firing pin so that future rounds also get pierced.
You need to SMOOTH the tip of the firing pin to get rid of any sharp edge or gas cutting if there is any present.
Think light stoning, not major grinding.

[GREASY357]

hopefully this pic is better

[G-forceJunkie]

What does the firing pin look like and how much protrusion?

[TRAP55]

What Randall said.
FP protrusion is .055 -.065, and from the looks of those FP dents in the primers, it's going pretty deep.

[buffybuster]

Sometimes it's a primer problem and then the gas from the piercing will erode the tip of the firing pin so that future rounds also get pierced.
You need to SMOOTH the tip of the firing pin to get rid of any sharp edge or gas cutting if there is any present.
Think light stoning, not major grinding.

Concur with this statement

[ar15barrels]

hopefully this pic is better

Besides the primers being pierced, those loads are also quite hot by how much blanking I see of the primer cups.

[Ronin6]

Besides the primers being pierced, those loads are also quite hot by how much blanking I see of the primer cups.

For my education what do you mean by “ blanking “

[pacrat]

S&B ammo is typically hotter than US ammo makers in 7x57. Due to the vast numbers of old soft mausers chambered in it. Especially the less than [up to snuff] Oviedo Arsenal Spanish types.

The unpierced primer looks a bit flat. But not enough that it should cause over pressure problems. JM2c.

For my education what do you mean by ? blanking ??

Rather curious regarding the term myself?

OP, was there any extraction difficulties, like overly hard bolt lift? Or having to jerk the bolt rearward?

[Flouncer]

I have the same weapon, I think. Chileo Modelo Model 1898 Crest stamped 1912. So same firing pin. Maybe ! On at least it's fourth barrel. Original in 7x57 arsenal converted to 7.62 NATO and then to 6mmBR to 6.5-06. The first indication of pressure in my two barrels is smear or light scuffs on the primer or case head from the bolt face rotating during extraction. I always back down .2 grains when I get that. Curious from those that know more, how can the OP easily measure the firing pin protrusion ? My cheapo but accurate micrometers dont have a rod or pin the slides out like my calipers. Just jaws that close. Thanks

[TRAP55]

Curious from those that know more, how can the OP easily measure the firing pin protrusion ? My cheapo but accurate micrometers dont have a rod or pin the slides out like my calipers. Just jaws that close. Thanks

Flouncer, I've got the depth measuring rod on mine. I suppose it wouldn't take much to duplicate what the Russians did on the Mosin tool. Piece of scrap, file a .055 groove, and a .065 groove in it. You could measure those with your calipers to make sure the cuts are right.