PPU .303 British - Short Cases?

[roundyuk]

Morning all,

Took my No4 to Bisley (UK) yesterday to put some rounds down on the ETR - shot 25 rounds and out of those, two had holed primers. Have done some research and a huge thread started by calling out head space issues; but then it started talking about short cases in PPU ammo. Considering I only had two out of 25 I am leaning towards the later, but just wanted some opinions.

My mates No4 was doing this with the exact same ammo in Wales a few months back when his firing pin was destroyed!

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[hayboy]

Hi Roundy.
I'm not sure from your post - are you using ppu factory ammo or reloading using ppu cases? If you're reloading what primers are you using?
If you think you have short cases have you measured the ones you've shot and got any info?

[roundyuk]

Hey, I've just grabbed the vernier - quick measurements:

Primers ok - 2.225 2.212 2.214 .2.224

Primers holed 2.224 2.224

Really weird, the case lengths look the same if you're talking 10ths of an inch...

Pic of good vs. bad case attached

Factory ammo BTW

[30Three]

I don't see how the case length can affect the primer /firing pin contact when it's a rimmed case.
Personally I would be looking at firing pin protrusion and the shape of the striking end of the pin.
I would not expect factory ammo to have poorly seated primers; but I suppose it would be worth looking at any unfired rounds that you have left.
However I've used a lot of PPU factory ammo without issue and now happily reload the cases. It's good stuff generally. Could be worth contacting PPU to see if they've had a dodgy batch of primers.

[Parashooter]

Polish your rough firing pin.

[Aussie48]

I have never had a problem with PPU ammunition, considering the amount they churn out it is to be expected that the occasional thin primer makes it through. Whinchester have had batches of thin primers make it onto the market.

Dick

[Roy W]

I had a similar problem a few weeks ago, with both PPU and S&B. I popped into Fultons, and they polished the tip of the firing pin, problem solved.
The small pieces of brass from the primers had blown back into the bolt head, also causing the firing pin to protrude after a few shots.

Not had a problem since

[roundyuk]

Ahhh, interesting, looking at the primer on fired cases I can see rough marks (like the firing pin on the left). I shall have a Google about polishing. Is there a factory spec for firing pin protrusion?

[Parashooter]

This problem has nothing to do with primer quality, headspace, case length, etc. It's the natural result of a rough firing pin tip, even if the irregularity can't be seen without magnification. Look at this enlargement of the intact primer shown above. See the jagged crater in the middle? That's the reverse impression of a seriously rough pin. (Imagine the different results from poking a toy balloon with a fingernail and with your elbow. Might help some folks understand why we need a smooth pin surface to avoid primer damage.)



There's no great skill required to polish a rough pin - just remove the bolt head and rub the pin's surface around on a piece of very fine abrasive cloth or paper held on your other palm. Thus cushioned, the abrasive will naturally produce a smooth, hemispherical tip.



If you polish off too much and end up with insufficient protrusion (under ~.040"), a new striker is the standard fix - but will require a striker removal tool and some study of what it takes to maintain the proper relationship of bolt, bolt head, cocking piece, and striker.


Contact of striker flange and rear of bolt head (B) controls pin protrusion (A).

[browningautorifle]

Another thing affecting a pierced primer is high pressure. Hopefully it's your firing pin that's at fault.