troubleshooting pierced primers

[ruger438]

I am working with a 17-223 I picked up used. The problem is about  1 in 5 primers are pierced. primers are not cratered, just a little pinhole at the bottom of the primer dent. I checked the firing pin, and there is some torching, whether it was there before I fired it, I have no idea. the firing pin protrudes about .050 from bolt face, is that too much? nearly every other primer has a little spot that almost looks like the primer cup smashed up against the anvil.
 I thought maybe thick neck, but loaded round neck dia. is .1995, fired case neck dia is .204 wich seems to indcicate sufficient chamber clearance
 Primers are not flattened at all
 The load is 23.5 grn h-414 in necked down mil 223 brass with CCI  small rifle primer. That charge weight is 1 grain under starting load per some old Hodgden data.

The gun is a heavy barrel on a Karl Gustav 96 Swedish Mauser action
Could I possibly need to change firing pins for a small rifle primer?

What could be causing this?

[Grumulkin]

Pierced primers are high pressure until proven otherwise.  Get a new loading manual, double check everything and consider decreasing the load.  Make sure the cases are trimmed to the proper length and the bullets are not actually engaging (close but not touching) when a round is chambered.

One pierced primer will burn the firing pin.  If you keep this up you'll be replacing the fireing pin.

There is no difference in a firing pin for small rifle as opposed to large rifle primers.

[ruger438]

thanks for the reply. pressure seems the safest assumption, there is very little new data out there for the 17-223 so  I could just end up getting this gun rechambered for 17 rem to simplify things, but it does bug me I havent found the cause. I guess checking headspace would be good idea.
 Another thing is the barrel never seems to get clean, about the time patches come out clean I brush, and patches are black again.

[jhalcott]

  the torching may have pointed your firing pin.If it isn't a smooth "ball" on the end have a GOOD gunsmith look at it It may need some touch up. As has been said treat it like a high pressure thing till you KNOW what caused it. That "old DATA" may well be too hot with the lot of powder you are now using. One grain in any .17 caliber is a BIG jump. In my 17 REM. I work up in half grain increments or LESS. 2 tenths of a grain higher than a safe load make the bolt hard to open. I dropped back a full grain .  Try one of the electronic cleaners to remove the copper fouling.

[RugerNo3]

Military brass is smaller in the internal dimensions then commercial brass. You may find it is as much as 2gr capacity smaller. You are running with a wildcat and your data may be nonexistent or worked up with commercial brass re-sized. Your discretion. A chronograph is almost a necessity.

[GregP42]

H-414 can build pressure very fast. If you can find data for another powder, I would use it. Like the others said, check the loading data you have, is it for commercial brass or military, and even then not all commercial brass is the same. Try to get as many thing right as you can, measure the case capacity and see what it is in grains of water. All these things will help when dealing with a wildcat like this one.

Greg 

[ruger438]

Thanks again everybody for the advice. Rugerno3, I'm kicking myself for not shooting the test loads over my chrony, it might have been revealing, as it is I'm not shooting any more of those loads for obvious reasons.
  I didnt realize 414 developed pressure quicker than some other powders, I  have data for 3031, BL-C2, and H-335, all off the loadata site,of which i have a subscription. I think I may back off 2 grains from those  starting loads but am leery of over reducing charges. This time I'll haul the chrony out and maybe then know where I'm at. I wish I could find some Varget data, as that is what I have on hand and it seems to work well in the 17 Rem but so far no luck in finding data for 17-223. I'm tempted to reduce 17 rem data wich in theory should work, but I am not ready to go down that road at this point without some other input.
 I've also read on the Saubier site (which was recommended to me as a good source of small bore info) that the rem7 primer is designed for the 17 rem and handles pressure spikes better but i have no way to confirm that, but may try that as well. But to me a thicker primer cup only would be treating the pressure symtom, not fixing it.

[Lone Star]

When in doubt, RTFM.  On page 55 of Speer #13: 

"Pierced primers are sometimes assumed to be indicative of high pressures.  However, most pierced primers are the result of a rough or improperly shaped firing pin.  Even a small burr on the tip of a firing pin can cause the primer to pierce." 

You now have the cause - and the solution - to your problem.

The mention of heavy fouling is typical of .177" barrels, particularly those from some years ago when the importance of cleaning was not as well known.  My recommendation is to not waste time with typical bore cleaning solvents, use Remington 40X cleaner - follow the instructions on the bottle.  An alternative is a strong copper solvent like Sweets or Barnes.  But the reality is that a 'little' darkness on a patch does no harm if the fouling is in pits or 'micro' grooves in the bore - that fouling doesn't come into contact with the bullet anyway.

I have shot a huge amount of W760 (same powder as H414) and have never seen it to be more sensitive to pressure spikes at higher pressures than other similar propellants.  But I have never loaded a .17 with it either as there are more appropriate powders available. 


.

[Lead pot]

The 17-223 and the 17-222 are a natural for high pressure spikes, you want to remember that you will have pressure problems from under loading as well as over loading.
Make sure you didn't get into the small pistol primers by mistake.
Kurt

[PaulS]

I would guess that you are shooting over pressure rounds. Check your data with good sources - the on-line powder companies all have data for the cartridges that are new to the sport. Definitely have your firing pin polished to get rid of any damage. The protrusion is right where it should be at .060" but you should check the firing pin hole to make sure that it fits without excessive play.

[bobg]

I had a lot of pierced primers with my Rem. 700 in 222 mag. till i switched to Remington 7 1/2 primers. Problem solved. Give them a try.
                bobg