Pierced primer! Trip to the gunsmith?

[Chanonry]

On 6/9/2019 at 7:53 PM, VarmLR said:

with stiff loads

still blaming the primer ...? 😂

[Laurie]

The original model SR primers were designed for the low-pressure .22 Hornet in the 1930s. Many such rifles had weak firing mechanisms as they were converted rimfires or built on elderly small single-shot Martini or falling-block actions. So primer cups were made of a soft brass alloy and are 0.020" thick to ensure reliable ignition and they were plenty strong enough for 22H pressures and the similar cartridges that followed it like the Bee.

When Remington introduced the .222 Rem cartridge with its 52,000 psi peak pressure in 1950, the company decided its model 6 1/2 primer was inadequate for these pressures, so introduced the model 7 1/2 'Magnum' primer for this cartridge. It had the same explosive pellet as the 6 1/2 so the 'magnum' bit was solely the increase in cup thickness from 0.020" to 0.025" and maybe a bit tougher alloy. (It has since been replaced by the 7 1/2BR model originally introduced for the 17 Rem which needed a slightly 'hotter' recipe.)

The 'soft' / weak models are:

CCI-400

Rem 6 1/2 BR

Murom KVB-223 / older copper coloured PMC SR

Winchester WSR (0.021" cup thickness) - but only more recent brass colour WSRs, older silver ones were thicker / tougher.

 

Federal 205s and 205Ms are nominally 0.225" thickness.

Everything else is 0.025"

 

The thin / weak models shouldn't be used in higher pressure cartridges such as 223 with full loadings. For decades Remington printed this on its 6 1/2 packaging but dropped it in recent years for some reason.

So the OP has fired thousands of his loads with a too-weak primer and had no problems no doubt due to a mild load / pressures. Fair enough, but there will be little margin and as another post points out, there can be the occasional faulty or thinner example or production lot.

Personally, I know what my choice of primer would be for 223 - always a thicker model - but in this case, I probably wouldn't worry ............ until or if it happens again.

[Gungrinner]

💥 Boom 💥

Another truth bomb from the wise one.

 

[Popsbengo]

35 minutes ago, Laurie said:

The original model SR primers were designed for the low-pressure .22 Hornet in the 1930s. Many such rifles had weak firing mechanisms as they were converted rimfires or built on elderly small single-shot Martini or falling-block actions. So primer cups were made of a soft brass alloy and are 0.020" thick to ensure reliable ignition and they were plenty strong enough for 22H pressures and the similar cartridges that followed it like the Bee.

When Remington introduced the .222 Rem cartridge with its 52,000 psi peak pressure in 1950, the company decided its model 6 1/2 primer was inadequate for these pressures, so introduced the model 7 1/2 'Magnum' primer for this cartridge. It had the same explosive pellet as the 6 1/2 so the 'magnum' bit was solely the increase in cup thickness from 0.020" to 0.025" and maybe a bit tougher alloy. (It has since been replaced by the 7 1/2BR model originally introduced for the 17 Rem which needed a slightly 'hotter' recipe.)

The 'soft' / weak models are:

CCI-400

Rem 6 1/2 BR

Murom KVB-223 / older copper coloured PMC SR

Winchester WSR (0.021" cup thickness) - but only more recent brass colour WSRs, older silver ones were thicker / tougher.

 

Federal 205s and 205Ms are nominally 0.225" thickness.

Everything else is 0.025"

 

The thin / weak models shouldn't be used in higher pressure cartridges such as 223 with full loadings. For decades Remington printed this on its 6 1/2 packaging but dropped it in recent years for some reason.

So the OP has fired thousands of his loads with a too-weak primer and had no problems no doubt due to a mild load / pressures. Fair enough, but there will be little margin and as another post points out, there can be the occasional faulty or thinner example or production lot.

Personally, I know what my choice of primer would be for 223 - always a thicker model - but in this case, I probably wouldn't worry ............ until or if it happens again.

excellent info, thanks v.much for sharing

[MrCetrizine]

I've had no issues since that one.

I also contacted CCI and was told that the 400 is fine for a bolt action .223 unless you exceed maximum loads in recommended published data (they didn't state what recommended published data was and I didn't ask). But they don't recommend the 400 in a semi auto with a heavy floating firing pin as slam fires can sometimes occur though are not common.

[VarmLR]

Must admit, I just use the .025" cup thickness primers now in .223.  Some find the CCI 400s fine, with no issues, others seem to have issues so it's likely a combination of factors including loads used and firing pin design.  My .223 firing pin seems to leave a crater-like mark (even with low pressure loads) rather than the clean dent of my Tikka rifles and is definitely a little harder on the primers.  As Laurie says, batch variations and higher loads (not over pressure, just near the higher end) are reason enough to pick the .025 imho.

[Bob57]

I had a pierced primer problem awhile ago with my .204 and vn530 powder so have recently changed to remington 71/2's , so far no probs,and in the heat, settling on only .1 of a grain of vn530 lower than when blowing fed gold medal primers.