The pierced primer conundrum

[Bruce51]

Having just read through the thread on pierced primers with Bluedot it seems that we need to discuss this further.

This thread will be to discuss the occurance of pierced primers and the specifics of the load used and the gun type.

Gun #1

Having recently acquired a Single Seven working up loads has seen many instances of primer piercing.

While you would think that it is the high end magnum loads that are the most problematic this is not the case.

Just yesterday 24 out of 32 primers pierced with a load of 3.2 grains of SR 7625 and a 90 grain Hornady SWC.

Primers were CCI small pistol and in fact all primers pierced were CCI.

Since this same load is shot out of a S&W 31 without the primers being pierced the problem seems to be with the Single Seven.

With a load of 12 grains of H110 and a Hornady 100 grain XTP I tried CCI SPP and the primers were well flattened.

Switching to CCI SRP the primers were not pierced or flattened but I did have FTF on several rounds.

Primers were reseated to just be sure and still several needed a second strike to fire.

Gun #2

I have a Ruger BH in .30 carbine as well.

For quite some time I have been having pierced primers with moderate loads to the point of firing pin erosion.

The primers used have been CCI SMP, CCI SRP and Remington SRP. The load was 4.5 grains of Unique and a 110 grain cast bullet.

I have since reduced this to 4.2 grains to reduce leading. Even with this moderate load primers are getting pierced even the CCI SRP.

I did order and install a new firing pin. Still the primers were being pierced and I eventually reduced its length at least .010" of and inch maybe more.

That helped some but primers are still being pierced.

Gun #3

Marlin 1894 .357 magnum

With a load of 16 grains H110, CCI SPMP and a Remington 158 grain JSP some primers are getting pierced. This had never occurred in my earlier load development with this rifle.

Dating back to the 1980's I went up to 17 grains of H110 with a velocity of 1700fps without having pierced primers.

Loads up to 12 grains of Bluedot with the same bullet and CCI SPP were never a problem except for flat primers.

These loads are still being fired in a 686 without the primers getting pierced.

Since only specific guns, some old and some new seem to be piercing primers what are the dynamics in play?

Can this be a weak hammer spring issue or a headspace problem? Have primers become more brittle or less ductile?

I feel that I need to try to do some spring replacement in the Marlin, Blackhawk and the Single Seven.

If it were the primers then every firearm would have the same issue.

My reading on this issue shows that rifles are equally effected. Hopefully a pattern will emerge and solutions suggested to try to eliminate pierced primers .

If anyone else is having this issue please post the relevant information. I'm looking forward to your thoughts on this matter.

BLM

 

[fredj338]

I think individual firing pins are the biggest culprits of pierced primers, especially if the loads are not max or exhibiting other over pressure issues. Sometimes simply stoning the very tip of the firing pin, will remove any sharp edge that can start the process.
IMO, using rifle or mag primers in handguns to avoid the pierced primer is only masking the cause.

 

[SMSgt]

Can't help you. I've never had a primer pierce.

 

[calmex]

In the case of revolvers, if the cylinder has excessive end-shake or if it is a cylinder that has been "installed" in a revolver for which it was never originally intended (many N-frame revolvers here in Mexico have .38 Special Heavy Duty or Outdoorsman cylinders installed in them to replace the .357 cylinders that came originally) primers can be pierced upon firing. If the headspace is a little long -- caused by either not properly fitting the cylinder or because of excessive end-shake -- the primers will crater.

Sticky extraction also goes hand-in-hand with these improperly fitted cylinders. The loads to not need to be maximum loads, and in fact light .38 loads will still crater -- although perhaps not pierce -- the primer and extraction will be sticky.

This condition is caused if enough metal has not been removed from the extractor star leaving the cases further forward than proper spec dictates yet still not so far forward that the firing pin cannot detonate the primer.

I've seen it quite often and our own gunsmith in Queretaro knows how to fix and fit such cylinders to cure and/or prevent the problem. But many Mexican gunsmiths simply get the cylinder to more-or-less work without worry about proper headspacing or fit and so those guns often (but not always) exhibit these conditions of sticky-extraction even on light loads and primer cratering or piercing.

I don't think this is exactly what you were looking for when starting this thread, but let me add that Blue Dot is a common powder used here because it contains "identifiers" and thus if it arrives through so many checkpoints one loses count generically packaged you still know what you have. Top loads often come close to the original Elmer Keith loading in the .38 Heavy Duty and if it was going to naturally crater just because it's Blue Dot, you'd think we'd have seen that but we haven't. However, I have heard that Blue Dot is tempurature sensitive and in the perpetual summer here in Central Mexico, perhaps our Blue Dot is always being fired within the powder's safe tempurature range. I don't know.

All the primer piercing I've seen in Mexican revolvers is more caused by incorrect headspacing of the cylinder rather than the powders being used. But that's just what I've seen.

 

[Big Cholla]

Every primer MUST be supported by a bolt face, a stiff enough FP spring and a FP that is NOT over length. The brass of the primer is very soft and very thin. As I read your post you are on to two of the possibilities and only need to include a review of the headspaces involved. I would discount the actual load being used unless it is way over pressure. Given an out of spec. condition of the three possibilities bad enough, any one of them could be the culprit. IMHO, it is probably a combination of two of them. Rarely is it a combination of all three. You need to put your gunsmithing/detective hat on and figure out which conditions are giving undesired results. ............. Big Cholla

 

[Bruce51]

It didn't happen without pictures

I usually don't start threads but the knowledge available here the best there is to consult.

I never concerned myself before with this issue as it was minimal.

Now with a brand new Ruger shooting and piercing about half the primers I think it is time to seek answers and solutions.

My first thought goes to the need for a stronger hammer spring.

Since the Marlin is well over twenty years old perhaps it is now weak.

The same applies to the BH in .30 carbine which has never had a new spring.

I tried to find some fired cases from the Marlin and the Ruger. Since they have already been processed I currently cannot photo them.

However here are the cases from the Single Seven. The .32SWL cases all have CCI SPP.

Note that some of the .327 cases have Winchester SPP.

The .327 cases on the left are CCI SRMP. They are not pierced but are not as deeply dented as the CCI SPP.

Cases on the right were loaded with CCI SPP and 4.2 grains of Unique and a Missouri 100 grain cast FP.

The question is why are the lower power loads having more pierced primers than the hotter JHP Loads?


While loads with AA5 and AA7 were also fired with CCI SPP and the 100 grain Hornady XTP there is not as many pierced primers on those loads.

BLM

 

[Shooter Magaven]

In the case of revolvers, if the cylinder has excessive end-shake or if it is a cylinder that has been "installed" in a revolver for which it was never originally intended (many N-frame revolvers here in Mexico have .38 Special Heavy Duty or Outdoorsman cylinders installed in them to replace the .357 cylinders that came originally). If the headspace is a little long -- caused by either not properly fitting the cylinder or because of excessive end-shake -- the primers will crater.

Sticky extraction also goes hand-in-hand with these improperly fitted cylinders. The loads to not need to be maximum loads, and in fact light .38 loads will still crater -- although perhaps not pierce -- the primer and extraction will be sticky.

This condition is caused if enough metal has not been removed from the extractor star leaving the cases further forward than proper spec dictates yet still not so far forward that the firing pin cannot detonate the primer.

I've seen it quite often and our own gunsmith in Queretaro knows how to fix and fit such cylinders to cure and/or prevent the problem. But many Mexican gunsmiths simply get the cylinder to more-or-less work without worry about proper headspacing or fit and so those guns often (but not always) exhibit these conditions of sticky-extraction even on light loads and primer cratering or piercing.

I don't think this is exactly what you were looking for when starting this thread, but let me add that Blue Dot is a common powder used here because it containes "identifiers" and thus if it arrives through so many checkpoints one loses count generically packaged you still know what you have. Top loads often come close to the original Elmer Keith loading in the .38 Heavy Duty and if it was going to naturally crater just because it's Blue Dot, you'd think we'd have seen that but we haven't. However, I have heard that Blue Dot is tempurature sensitive and in the perpetual summer here in Central Mexico, perhaps our Blue Dot is always being fired within the powder's safe tempurature range. I don't know.

All the primer piercing I've seen in Mexican revolvers is more caused by incorrect headspacing of the cylinder rather than the powders being used. But that's just what I've seen.

Well, Calmex, where was this explanation when I had my BlueDot issue

I think, In my case of pierced primers, this is the most likely cause and explains alot. You see, I replaced my cylinder and had little experience in doing this in a Colt. It shoots great, no extraction issues (and I shot plenty of full power) and not many flattened (CCI) primers. But I never made the connection with head-space, cylinder replacement and primers.

And as far as too long a firing pin... I just put an extra length pin in my 686 and not only does it never pierce primers..the dimples seem even more shallow now... very strange.

Thanks for the info.

Btw: before anyone berates me about shade-tree gunsmithing, this particular revolver was bought second hand in bad conditions for cheap just to fix up and see what I could do with it. Im not into ruining perfectly good guns to be a `Bubba` smith.

 

[Bruce51]

Good info so far. I'm getting some idea of which direction this may be headed.

Just out of curiosity I used a feeler gauge on the Single seven where the firing pin and cylinder meet.

It measured .055" and it seems to me that the firing pin just barely makes it to the primer.

So now I check the 686 and it is a whooping .050" in between the cylinder and the breech face. Still the 686 works perfectly. The FP protrusion is only .025" .

I know that this is comparing apples to oranges. Just need to know where the solution may be.

Is it possible that a longer firing pin is needed rather than shorter?

The FTF on SRMP seems to indicate a stronger spring or a longer FP is needed.

I think I will check the BH as well and check some FP protrusion too.

BLM

 

[Big Cholla]

Easy Answer:

.

The question is why are the lower power loads having more pierced primers than the hotter JHP Loads?


While loads with AA5 and AA7 were also fired with CCI SPP and the 100 grain Hornady XTP there is not as many pierced primers on those loads.

It would be my educated guess that the lower power loads are not being slammed back into the backstop quick enough and the hammer/firing pin is retreating quickly enough for the primer to loose support in the FP strike area and the pressure is still enough to blow out the weakened FP dimple.

............ It is all a game of milli seconds. ............. Big Cholla

 

[Bruce51]

.

The question is why are the lower power loads having more pierced primers than the hotter JHP Loads?


While loads with AA5 and AA7 were also fired with CCI SPP and the 100 grain Hornady XTP there is not as many pierced primers on those loads.

It would be my educated guess that the lower power loads are not being slammed back into the backstop quick enough and the hammer/firing pin is retreating quickly enough for the primer to loose support in the FP strike area and the pressure is still enough to blow out the weakened FP dimple.

............ It is all a game of milli seconds. ............. Big Cholla

Thank you for that! I thought that this may be one possible reason.

Still pointing to things being not quite balanced between ignition of the primer and the rearward movement of the case.

Checking the Single Seven hammer spring it appears to be all that it can be.

If others Single Seven owners are having this issue perhaps a better spring may provide the solution.

AfAIK I have not found this posted anywhere else regarding the Ruger.

I checked the BH which also has this problem. The FP protrusion and the cylinder to breech face are at .022"

I'll try to order a new hammer spring for that revolver.

The Single seven FP protrudes .045" and the cylinder to breech face is .055" This is a much longer FP than is in the 686.

BLM

 

[NJM15]

Here's one also a CCI sp 500 I admit the load was up a little,(not max)
only happened once so im not concerned, continue to use CCI primers ,
in all my reloads