What would cause unusually deep firing pin holes in primers

mattygee1969 · February 23, 2009, 05:00 AM

I have just started reloding the ruger 204 round and tested some reloads at the range on the weekend. The loads were 29 grs win 748 powder, Nosler 40gr Spitser pojectiles and Win small rifle primers, fired from my Ruger M77vtr. I had some rounds that were harder to chamber than others but I put this down to the fact that I only necked sized the brass (could be wrong) other than that I had some reasonable groups. When picking up all the spent brass I noticed that some of the primers had excessivley deep firing pin holes in them. What is the cause of this, the primer apart from the deep hole seems to still be seated correctly and there isnt any other obvious signs that would indicate the cause.

cgaengineer · February 23, 2009, 06:53 AM

I am no expert

They may have not been seated deep enough or you could have an over pressure charge that is causing the primer to ride out of the case a bit. You could also have a loose primer pocket.

Do you notice any signs of over pressure?

steve4102 · February 23, 2009, 08:20 AM

Do you mean just deep or are they pierced? According to Hornady the Max load for the 204 Ruger/40gr bullets is 28.3gr of 748. 29gr may be to hot?

SL1 · February 23, 2009, 08:32 AM

Some things don't sound right.

Why were you "picking up all the spent brass" AFTER you finished shooting. When starting to reload a new combination of componenents, you should be carefully looking at EACH case after you fire it and BEFORE YOU FIRE ANOTHER. That way, you can catch a problem before it catches you. And, you can relate what you see to everything else that you noticed about that round.

For example, you said some rounds did not chamber easily and some did. That doesn't sound right either. Were the rounds that chambered easily the ones with the excessively deep holes, or was it the ones that chambered hard? If you want to figure these things out, you need to be paying close attention to things besides group size.

One other thought. You said that the rounds were all neck-sized. Since some were easy to chamber and some were not, it sounds like maybe these cases were not all from previous firings in YOUR gun. But, maybe they were fired in your gun, but with different power loads. Or, maybe you were seating bullets very near the lands and did not control COL very well, so some bullets were getting shoved into the lands and others were not. Or, maybe some of your cases are too long.

I will stop the list of "maybes" here, but be assured that there are a lot more of them. SO, in order to get USEFUL speculation from those of us on this forum, you really need to pay more attention to what is happening and provide us with a LOT more detail and information about how those details are apparently related.

If you don't, you might get an answer that says something like "Yeah, my rifle is like yours and I get some deep primer strike holes too - - they are caused by [something]." But, that is HIS gun with HIS reloads. They might be caused by something else in YOUR gun. If you don't compare your other factors, you might draw the wrong conclusion from a response like that. Some wrong conclusions can be dangerous, but more often, they just lead you down a blind path with regard to getting the accuracy or power that you are trying to achieve.

SL1

patchy · February 23, 2009, 07:31 PM

Had the same problem with piercing.Switched to cci 450,s instead of400,s.

mattygee1969 · February 24, 2009, 02:36 AM

Spoke to gun shop owner today stated ,poss thin brass on primer, he inspected spent shell and also commented on lack of high load signs. The only other small rifle primers he had were Federal No. 205, will give them a try and will pay more attention to spent brass in future.

n9viw · February 26, 2009, 01:32 PM

I just finished reading about this very issue in the Lee reloading manual. Make sure you're not accidentally using small PISTOL instead of small RIFLE primers, and ensure you're not running too large a fast charge, or too small a slow charge - yes, this can happen with slow-burning powder too! Also, make sure your bullets aren't seated too deep and are compressing the powder.

Other than that, I know nothing (Schultz!). Heck, I haven't even got my first set of dies in the mail yet. But I've been reading, oh boy have I. It's enough to make your head spin if you don't have the hardware in front of you!

steve4102 · February 26, 2009, 05:46 PM

Quote:

Also, make sure your bullets aren't seated too deep and are compressing the powder.

Does Lee actually say that compressing powder increases pressure? Every loading manual I have lists compressed charges in their data.

wncchester · February 26, 2009, 06:50 PM

The thingy that makes dimples in primers is the firing pin. If it's too long or protudes too far it will make deeper than normal dimples. If it's the right primer (not a pistol type) it's not likely to be a problem unless it's sufficent to pierce the caps. And that's quite rare.

Compressed powder charges, hi/lo pressures or new primers won't change that.

markr · February 26, 2009, 07:31 PM

Quote:

Does Lee actually say that compressing powder increases pressure? Every loading manual I have lists compressed charges in their data.

Some loads were meant to be compressed, and some are not. If you don't have published load data for a compressed load, then you shuld not be compressing it. Compressing a load results in a "Crunch" sound as you seat the bullet, and you should know if you are compressing it anyway if the powder is piled up in the case neck after you charge it.

Seating too deep (Compressing) increases pressures. Seating too far out can increase pressure also if the ogive of the bullet is sitting on the lands. That is why you back the load down a couple grains and work back up if you change ANY aspect of the load recipe.

The original shooter probably had exceeded the C.O.L for his gun, resulting in hard to chamber rounds, resulting in high pressures indicated by over penetrated primers. That's my guesses, but as others have said, more info is needed for a good diagnosis.

markr · February 26, 2009, 07:33 PM

Oh. OP, please don't hurt yourself.

SL1 · February 26, 2009, 08:47 PM

Let us remember that the OP said he shot a bunch of rounds, apparently all with the same load, and SOME had unusually deep firing pin marks, while others did NOT. Also, SOME were hard to chamber (not extract) and others were not. But, the OP did not know of any correlation between these two observations.

So, some things appear to be wrong, but there is little way to determine what until we see more information.

SL1

February 23, 2009, 05:00 AM	#1
mattygee1969 Junior Member Join Date: February 23, 2009 Posts: 2	What would cause unusually deep firing pin holes in primers I have just started reloding the ruger 204 round and tested some reloads at the range on the weekend. The loads were 29 grs win 748 powder, Nosler 40gr Spitser pojectiles and Win small rifle primers, fired from my Ruger M77vtr. I had some rounds that were harder to chamber than others but I put this down to the fact that I only necked sized the brass (could be wrong) other than that I had some reasonable groups. When picking up all the spent brass I noticed that some of the primers had excessivley deep firing pin holes in them. What is the cause of this, the primer apart from the deep hole seems to still be seated correctly and there isnt any other obvious signs that would indicate the cause. Last edited by mattygee1969; February 23, 2009 at 05:13 AM. Reason: wrong title

February 24, 2009, 02:36 AM	#6
mattygee1969 Junior Member Join Date: February 23, 2009 Posts: 2	Possibly Bad Batch Of Primers ?? Spoke to gun shop owner today stated ,poss thin brass on primer, he inspected spent shell and also commented on lack of high load signs. The only other small rifle primers he had were Federal No. 205, will give them a try and will pay more attention to spent brass in future.

February 26, 2009, 01:32 PM	#7
n9viw Junior Member Join Date: January 21, 2009 Location: Worth Co, MO Posts: 14	I just finished reading about this very issue in the Lee reloading manual. Make sure you're not accidentally using small PISTOL instead of small RIFLE primers, and ensure you're not running too large a fast charge, or too small a slow charge - yes, this can happen with slow-burning powder too! Also, make sure your bullets aren't seated too deep and are compressing the powder. Other than that, I know nothing (Schultz!). Heck, I haven't even got my first set of dies in the mail yet. But I've been reading, oh boy have I. It's enough to make your head spin if you don't have the hardware in front of you! __________________ Nick

February 26, 2009, 06:50 PM	#9
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	The thingy that makes dimples in primers is the firing pin. If it's too long or protudes too far it will make deeper than normal dimples. If it's the right primer (not a pistol type) it's not likely to be a problem unless it's sufficent to pierce the caps. And that's quite rare. Compressed powder charges, hi/lo pressures or new primers won't change that. Last edited by wncchester; February 26, 2009 at 06:55 PM.

February 26, 2009, 07:33 PM	#11
markr Senior Member Join Date: January 23, 2008 Location: Arsenal of Democracy Posts: 405	Oh. OP, please don't hurt yourself. __________________ I like to make beer, bullets, and jerky.....but not at the same time. Washed up 11B1P

February 23, 2009, 06:53 AM	#2
cgaengineer Senior Member Join Date: November 6, 2008 Posts: 264	I am no expert They may have not been seated deep enough or you could have an over pressure charge that is causing the primer to ride out of the case a bit. You could also have a loose primer pocket. Do you notice any signs of over pressure?

February 23, 2009, 08:20 AM	#3
steve4102 Senior Member Join Date: December 23, 2005 Location: Minnesota Posts: 2,952	Do you mean just deep or are they pierced? According to Hornady the Max load for the 204 Ruger/40gr bullets is 28.3gr of 748. 29gr may be to hot?

February 23, 2009, 08:32 AM	#4
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Some things don't sound right. Why were you "picking up all the spent brass" AFTER you finished shooting. When starting to reload a new combination of componenents, you should be carefully looking at EACH case after you fire it and BEFORE YOU FIRE ANOTHER. That way, you can catch a problem before it catches you. And, you can relate what you see to everything else that you noticed about that round. For example, you said some rounds did not chamber easily and some did. That doesn't sound right either. Were the rounds that chambered easily the ones with the excessively deep holes, or was it the ones that chambered hard? If you want to figure these things out, you need to be paying close attention to things besides group size. One other thought. You said that the rounds were all neck-sized. Since some were easy to chamber and some were not, it sounds like maybe these cases were not all from previous firings in YOUR gun. But, maybe they were fired in your gun, but with different power loads. Or, maybe you were seating bullets very near the lands and did not control COL very well, so some bullets were getting shoved into the lands and others were not. Or, maybe some of your cases are too long. I will stop the list of "maybes" here, but be assured that there are a lot more of them. SO, in order to get USEFUL speculation from those of us on this forum, you really need to pay more attention to what is happening and provide us with a LOT more detail and information about how those details are apparently related. If you don't, you might get an answer that says something like "Yeah, my rifle is like yours and I get some deep primer strike holes too - - they are caused by [something]." But, that is HIS gun with HIS reloads. They might be caused by something else in YOUR gun. If you don't compare your other factors, you might draw the wrong conclusion from a response like that. Some wrong conclusions can be dangerous, but more often, they just lead you down a blind path with regard to getting the accuracy or power that you are trying to achieve. SL1

February 23, 2009, 07:31 PM	#5
patchy Junior Member Join Date: January 25, 2009 Posts: 12	Had the same problem with piercing.Switched to cci 450,s instead of400,s.

February 26, 2009, 08:47 PM	#12
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Let us remember that the OP said he shot a bunch of rounds, apparently all with the same load, and SOME had unusually deep firing pin marks, while others did NOT. Also, SOME were hard to chamber (not extract) and others were not. But, the OP did not know of any correlation between these two observations. So, some things appear to be wrong, but there is little way to determine what until we see more information. SL1

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