Firing pins

[jim vaughan]

I recently had problems with my 2 STI type open guns in 9mm major. The firing pins indentations in the primers were quite deep and during a competition I had an accidental discharge with my finger outside the trigger guard.

Upon checking various primers I saw that the tip of the extended firing pins in both guns were flat with sharp edges. Some of the primers (WW SPP) had holes on the sides of the primer indentations. The firing pin had extensive powder marks along its length. I reground the firing pin tips to a normal curved shape.

This shows just another area to check in the never ending journey to a reliable open handgun.

The attached images show the 2 extended pins together with 2 normal pins. The 2 rows of fired cases show normal and pierced primers.

[jwhittin]

Interesting. I have not seen this before so its a good thing to be aware of.   Was the firing pin protruding past the breach face? Is that what caused the discharge?

 

What brand of firing pin has the square tip? 

 

 

Edited March 10 by jwhittin

[shred]

None that I'm aware of come with a flat tip, but they do get mashed in-use, especially with flat primers like the OP has, so when cleaning, pull the pin and check for burrs around the front which is the first sign.

 

[Sarge]

What were the circumstances of the AD?

[Farmer]

On that bottom pin is that carbon build up back where the taper widens or is that peened from hitting the pin channel? Looks shaped differently (longer) than the others. That could have made it stick and cause the AD. Primer wipe can also break or wear the tip down too. 

[kuletchi1]

In my knowledge and what I was told when it comes to open is to use rifle primers. Also I just checked my open guns and none of them have the protruding firing pins. From a newbie 

[shred]

If you (or your builder) haven't put an extended firing pin in your pistol, you don't have one and this is a non-issue.

 

I like having them flush with the breechface with the hammer down, which is over GI length, but provides useful support for major loads.

 

[jim vaughan]

The AD happened immediately after firing at 2 targets then straight into a magazine change. The RO was very close and confirmed that he saw the spent magazine start to fall from the gun when the shot went off. I have very short trigger fingers so I regrip when mag changing. 

When I stripped my primary gun I found that the firing pin and channel were coated with a hard grey film that was difficult to remove. The long firing pins are flush with the breachface when the hammer is down.

I do not know what brand of extended firing pins I have.

[shred]

If the mag was falling, it wasn't a slam-fire from the firing pin stuck out because that would have happened immediately on slide closing. 

 

Something knocked the sear off the hammer.  Could be the mag bumped the trigger bow on the way out if the sear was barely hanging on.

 

[zzt]

I don't care for flush with the breech face firing pins like the Dawson.  I prefer extended ones such as Cheely's.  If you had grunge in the firing pin channel, it is possible it got stuck and protruded a bit.  It may have dented the primer, but not fired it.  Then you changed your grip to drop a mag.  That movement and push may have been enough to finally fire the primer.

 

Unless you are using really clean burning powder and JHPs, the firing pin and extractor tunnels will collect a lot of crap.

[CHA-LEE]

The primers are SUPER FLAT. Mega over pressure. You will get pierced primers when the pressure is insane. I am yet to see any manufacture sell "Square" tipped Firing Pins. I think what you are seeing is the tip of the Firing Pin has actually been sheered or gas cut off due to the excessive pressure and gas flowing back through the pierced primer. Welcome to 9 Major. Crazy stuff happens when you load to pressures WAY BEYOND SAAMI spec for a given cartridge. Try using Rifle Primers as they are harder and resist the over pressure scenario a little better. But you may have to switch powders or reduce the powder drop to chill out the pressure spikes.

[CHA-LEE]

9 Major sounds great until you are faced with the realities of using a load that is well beyond the SAAMI spec for the cartridge. There is no free lunch shooting Open Major. Spend money on 38 Super Comp brass which will work without issue. Or try to make 9 Major work and deal with all of the issues that come along with that.

[Maximis228]

6 minutes ago, CHA-LEE said:

9 Major sounds great until you are faced with the realities of using a load that is well beyond the SAAMI spec for the cartridge. There is no free lunch shooting Open Major. Spend money on 38 Super Comp brass which will work without issue. Or try to make 9 Major work and deal with all of the issues that come along with that.

I've seen just as many issues with 38 S/SC. I've been shooting 9 major for about a decade now. Easily 300,000 rounds loaded using mixed range brass. I've cracked 1 slide and cracked 1 barrel lug during that time frame. I've seen local 38 S/SC guys do much worse.

 

People who chase the uber flat gun with ridiculously high charges (AA7, 3n38, Major Pistol and the like...) while compressing powder are the ones who run into issues. People laugh... but my 7.2 WAC under a 124 JHP pushing 173 PF has been awesome for me. I've tested out every combo under the sun and I always come back to WAC. 

[CHA-LEE]

1 hour ago, Maximis228 said:

I've seen just as many issues with 38 S/SC. I've been shooting 9 major for about a decade now. Easily 300,000 rounds loaded using mixed range brass. I've cracked 1 slide and cracked 1 barrel lug during that time frame. I've seen local 38 S/SC guys do much worse.

 

People who chase the uber flat gun with ridiculously high charges (AA7, 3n38, Major Pistol and the like...) while compressing powder are the ones who run into issues. People laugh... but my 7.2 WAC under a 124 JHP pushing 173 PF has been awesome for me. I've tested out every combo under the sun and I always come back to WAC. 

 

I am not saying that 9 Major it can't be done successfully. I also agree that if people are not paying attention to details while reloading ammo they are going to have issues regardless of cartridge.

 

Case in point is the OP's pics of the fired brass. How the flatness of the primers and deformed primer hits doesn't ALREADY tell the user that there is a significant pressure problem with the load blows my mind. But it happens all the time. 

 

Reloading 9 Major ammo isn't like snapping together Lego pieces where you are kept from screwing it up. You can ABSOLUTELY screw up 9 Major ammo if you are not paying attention to the details.

Edited March 13 by CHA-LEE