Yet another pierced primer thread... (pin hole in primer radius)

[Emmett Dibble]

I've been googling and searching this forum but you can only read through so many threads till your tired of not finding exactly what your looking for....

6X45, happened on second firing but now some cases are up to 4th firing, Remington commercial brass. 2 different loads, one 105 Bergers VLD with 21gr Benchmark, the other 68 Berger flat bottom with 25.5gr Benchmark.

Was having maybe 1 in 20 with Remington 7 1/2 primers, new load with Fed 205M and it dropped to maybe 1 in 50.

Not blowing out through firing pin hole, not around primer pocket, it's blowing a pin hole out in the radius of the primer cup (which obviously flame cuts the bolt face).

Ideas? No heavy bolt lift, primers still show radius, not flattened, firing pin dimple not cratering back out, no flow around firing pin bore, no ejector dimple on the brass, not too much head space, prime off the press and the hand pressure feels normal. 700 action, PTG bolt, factory pin, new Wolf spring...

I'm not terribly worried but it is annoying that my bolt face looks like it has acne.

 

[kiwijohn]

Is the flash hole perhaps oversize and letting too much pressure to exhaust this way? If the failure occurs prior to full pressure peak, that would explain why the primers aren't flat, and the excess is bleeding off through this newly formed release valve.

 

[Cfshooter]

I've been googling and searching this forum but you can only read through so many threads till your tired of not finding exactly what your looking for....

6X45, happened on second firing but now some cases are up to 4th firing, Remington commercial brass. 2 different loads, one 105 Bergers VLD with 21gr Benchmark, the other 68 Berger flat bottom with 25.5gr Benchmark.

Was having maybe 1 in 20 with Remington 7 1/2 primers, new load with Fed 205M and it dropped to maybe 1 in 50.

Not blowing out through firing pin hole, not around primer pocket, it's blowing a pin hole out in the radius of the primer cup (which obviously flame cuts the bolt face).

Ideas? No heavy bolt lift, primers still show radius, not flattened, firing pin dimple not cratering back out, no flow around firing pin bore, no ejector dimple on the brass, not too much head space, prime off the press and the hand pressure feels normal. 700 action, PTG bolt, factory pin, new Wolf spring...

I'm not terribly worried but it is annoying that my bolt face looks like it has acne.

Were these cases previously crimped? I had the same issue and manufacturer said was from primer pockets.

 

[Emmett Dibble]

Were these cases previously crimped? I had the same issue and manufacturer said was from primer pockets.

No. Commercial brass (non-military crimped). Bought as once fired factory 223 hunting rounds. The brass is being replaced but with brand new 223 Remington commercial brass but figure will still have the same problem...

 

[gunsandgunsmithing]

I'm intrigued. If it was only one primer brand I would've been confident blaming the primer, but two brands? All I can say is look at the common denominators and let us know what you find., of course brass being one of those. Interesting.

edit...your firing pin needs some attention, imho, but I don't see how it's related to this problem. But to me, looks like it's seen a few pierced primers in its life.

 

[JB10]

Im using cci 450's in mine. Im using different powder and lighter bullets. From data i found years ago, ur 105 berger loads might be a little warm. What i had found someone stopped at 22.5 with 100gr bullet. The 68gr berger load should be ok. I think id try different brass. Ive mainly used LC or federal.

 

[Emmett Dibble]

I'm intrigued. If it was only one primer brand I would've been confident blaming the primer, but two brands? All I can say is look at the common denominators and let us know what you find., of course brass being one of those. Interesting.

edit...your firing pin needs some attention, imho, but I don't see how it's related to this problem. But to me, looks like it's seen a few pierced primers in its life.

That is why I switched to the 205M from the 7 1/2... when it happened at this last match again (all though much less frequently) obviously it isn't "just the primers"...

Several of the guys at the match who have decades more loading HP silhouette then I do were saying defective primers but I don't think so...

The 105 data is from Berger. I don't believe it's top of the load either. No other high pressure signs, brass looks good, not growing, no stuck cases or hard extractions or bolt face/extractor being imprinted on the brass. Just the random pin holes in the shoulder of the primer cup.

Going to change brass then if it still happens change to CCI 41's, I doubt anything is heavier built then those. But I don't know how consistent they are...

 

[gunsandgunsmithing]

That is why I switched to the 205M from the 7 1/2... when it happened at this last match again (all though much less frequently) obviously it isn't "just the primers"...

Several of the guys at the match who have decades more loading HP silhouette then I do were saying defective primers but I don't think so...

The 105 data is from Berger. I don't believe it's top of the load either. No other high pressure signs, brass looks good, not growing, no stuck cases or hard extractions or bolt face/extractor being imprinted on the brass. Just the random pin holes in the shoulder of the primer cup.

Going to change brass then if it still happens change to CCI 41's, I doubt anything is heavier built then those. But I don't know how consistent they are...

I agree that it doesn't look or sound like pressure. I'm just not sure what it is but will guess brass. Following because I'm very curious.

 

[Emmett Dibble]

Im using cci 450's in mine. Im using different powder and lighter bullets. From data i found years ago, ur 105 berger loads might be a little warm. What i had found someone stopped at 22.5 with 100gr bullet. The 68gr berger load should be ok. I think id try different brass. Ive mainly used LC or federal.

I couldn't get consistent ES/SD numbers out of LC brass... I'm shooting to 500 so I believe the numbers start mattering at that range. Numbers came down with the RP brass... tempted to go Lapua but not married to this barrel/chambering yet....

 

[Emmett Dibble]

Just for grins I decapped a 7 1/2 (brass colored) and 205M (silver). Pin hole in radius. Brass pockets are fine.

 

[jepp2]

Ideas?

It is a primer problem, not a load/gun problem. I've encountered it:

- with the Rem 9 1/2 primers from back in the 70's
- with older and newer Rem 7 1/2 primers
- with new WLR primers (Winchester bought back 10K from me and paid to fix my bolt face)

On the Rem 7 1/2 primers, it seemed to be much worse with primer pockets that were somewhat loose. Once I started culling those cases, the problem went away.

 

[Emmett Dibble]

It is a primer problem, not a load/gun problem. I've encountered it:

- with the Rem 9 1/2 primers from back in the 70's
- with older and newer Rem 7 1/2 primers
- with new WLR primers (Winchester bought back 10K from me and paid to fix my bolt face)

On the Rem 7 1/2 primers, it seemed to be much worse with primer pockets that were somewhat loose. Once I started culling those cases, the problem went away.

WOW. That definitely looks EXACTLY like what I am having.... Interesting....

One of the guys who said Primer issue at the last match suggested calling the manufacture and raising hell but honestly.... I'm not that guy and my time during the day is worth more then the primers on hand and bolt repair. I might though if it continues with new brass.

 

[gunsandgunsmithing]

Just for grins I decapped a 7 1/2 (brass colored) and 205M (silver). Pin hole in radius. Brass pockets are fine.

Looks like they are pushing back a lot while under pressure. Headspace been checked?

 

[Emmett Dibble]

Looks like they are pushing back a lot while under pressure. Headspace been checked?

Yes Sir. It's a Remage barrel, I have several. I use the go gage with a piece of celephane tape on the back ( +/- .001 thick) and the bolt handle just engauges the caming of the lugs but will not drop.

FWIW, I have a pair of 6CM guns that I know are running spicier then this one and use the same technique to head space and when the loads are too hot in development they flatten primers, leave ejector dimples and have heavy bolt lift.... this rifle exhibits none of those.

 

[JB10]

Im getting good numbers, but im not shooting out that far. Just a critter/ fun gun.

 

[Emmett Dibble]

Im getting good numbers, but im not shooting out that far. Just a critter/ fun gun.

Better then me... high teen ES, low teen SD... I shoot Black Powder Cartridge also and those dang things get single digits will very little effort... accuracy from the bullet though? That is a different story... lol.

 

[jepp2]

this rifle exhibits none of those.

Looking at your pictures, I notice the brass case head has a overly generous radius at the top of the primer pocket (common with R-P). This leaves more of the primer unsupported, not too different than I found when the primer pockets were loose. If you pick some brass other than R-P that doesn't leave as much of the primer unsupported, your problem may go away. Also looks like you have a good bit of clearance between your firing pin and the opening in the bolt face. It is causing the primer to crater, but not due to excessive pressure.

 

[Emmett Dibble]

Looking at your pictures, I notice the brass case head has a overly generous radius at the top of the primer pocket (common with R-P). This leaves more of the primer unsupported, not too different than I found when the primer pockets were loose. If you pick some brass other than R-P that doesn't leave as much of the primer unsupported, your problem may go away. Also looks like you have a good bit of clearance between your firing pin and the opening in the bolt face. It is causing the primer to crater, but not due to excessive pressure.

Didn't think of that.... I may buy some different brass and try them. I didn't consider the RP brass would be radiused at the pocket. Kinda Glock unsupported chamber bulge thing. I like that.

 

[DRK]

I had the same problem with Wolf small rifle primers, R-P brass in my 6 TCU built off a Ruger 77. Did not appear until this time of year for loads that ran fine in the spring, temp sensitivity of H335 I think did not help anything.

I ended up junking the R-P brass as some of the primer pockets were loosening up. CCI 400s were better in not blanking.

Currently, I am running Nosler brass, CCI 400s, Speer 70 gr TNTs, working good for shooting wood chucks.

 

[JB10]

I looked at the load data from berger and they show a max of 20.4 with the 105/108 and benchmark. I know they are conservative on their loads though. I do not feel its a pressure issue. Id try different brand brass.