Primer flow due to weak firing pin?

[Black Jaque Janaviac]

I posted these pictures a while back in another thread. We determined that the cause of the primer flowing into the firing pin channel was because I was using Rem 1 1/2 primers. I switched to a different brand and the primer flow is much less pronounced with WSPs and CCI500s.

However, I do notice the problem with some of them and I did get the problem recently while working up loads with other powders and other bullets - using WSPs and CCI500s. Sometimes this was before even getting to the recipe max.

I am inclined to just ignore it except that it can create a problem. This is from a Kimber µ9 so the primer flows back into the pin-hole, then the barrel drops down which shears some of the metal off the primer. This has caused misfires as the metal clogs the firing pin channel.

So. . .

I began to think. From the get-go I've notice that this gun doesn't make a very pronounced primer dimple. It is enough to consistently ignite the rounds (provided the channel isn't clogged), but the dimples are tiny. Look at the dimples on the cases on the right of the photo. That's pretty weak, no?

Do you think that the weak firing pin strike could be the cause of the primer flow-back and shear, which in turn clogs the firing pin channel? If the firing pin hit the primer harder, the dimple would be closer to the actual diameter of the firing pin, which would form a dome. The dome would resist flow-back.

[url=https://flic.kr/p/24SW9oh]

[Black Jaque Janaviac]

Here is a picture of the bolt face with the firing pin protruding as far as I can push it with a pencil.

Oh. I have done the pencil test by firing with only a pencil (or pen) in the chamber. It will send the pencil out of the barrel, but only several inches high when pointed straight up. Videos I have seen of other guys doing this test show the pencil flying many feet high.

[url=https://flic.kr/p/J3xJDe]

[Larry Gibson]

I'd put a new hammer spring in it.

[David2011]

Yep, new hammer spring (mainspring). Make sure the firing pin channel and mainspring housing are clean and the hammer/strut isn’t dragging. Any or all of those issues could slow down the hammer.

Wouldn’t hurt to measure the diameter of the firing pin as well. It looks like there’s a little room between the firing pin and the bolt face, but that could also be a chamfer. With the firing pin spring removed, if the firing pin can be wiggled sideways or vertically then there’s too much space between it and the firing pin hole. It’s probably not worn but could be too small for the hole.

Firing pins are available in .068, .075 and.093” diameters.

[Gtek]

Find a pin gauge set and measure FP hole ID, if a firing pin can be found to give .001"-.002" great. I have purchased a larger sized pin and fit to hole, but make sure hole is clean by gauging from both ends go-no-go style. One manufacturer sticks in my head that was very generous in pin fit.

[truckjohn]

Does it do the same thing with factory ammo?

[Black Jaque Janaviac]

Does it do the same thing with factory ammo?

Weak primer dents with factory ammo? Yes.

Shaving metal off primer as seen in cases on the left of photo? No. But I haven't fired factory ammo other than Fiocchi extrema and Win. Whitebox, no +P either.

[truckjohn]

If it's not blowing/extruding primers up in factory ammo - it's not the gun.

It's either your primers or your loads.

[country gent]

If it has a rebound spring on the firing pin check replace it a to heavy spring here can slow lighten the blow also. As said above check firing pin channel for built up debris also. Also check fir of firing pin in hole as excess clearance can allow some flow back. The pins protrusion seems to be on the long side in the picture. Maybe a broken coil on the firing pin spring letting it set forward and pinching the pin?

[Iowa Fox]

There are several things that can cause primers to look like the ones in the picture. As long as they go off every time and you aren't piercing primers I wouldn't worry about it.

[243winxb]

The 1911 type guns have an inertia firing pin. If your is of this type, the pin does not stay in contact with the primer on firing.

Your load have reached maxamim pressure before getting to the book listed maximum.

The Rem 5 1/2 primer or any mag primer is better suited for a high pressure 9mm that runs at
35,000 PSI.

My Gold Cup photo. The pin goes forward till it makes contact with the primer.

[Land Owner]

If reloads on bullets that head space on the case neck, a taper crimp that allows the bullet to seat slightly forward into the chamber will result in weak firing pin strikes and the occasional Failure To Fire.

[jeepyj]

Marked to follow. We've been watching something similar with one of the fellows at the range.

[JimB..]

@Land Owner is likely on the right track, it is entirely possible that your reloads are over crimped. Because you have light strikes with factory ammo I’d guess that you’ve got too much headspace so the extractor is holding the bullet to the breechface. Plunk some ammo and show us the extractor marks on some fired cases if you can.

[Black Jaque Janaviac]

that allows the bullet to seat slightly forward into the chamber

I take it you mean the entire case seating slightly forward making it more difficult for the firing pin to reach the primer.

Plunk some ammo and show us the extractor marks on some fired cases if you can.

OK. The extractor marks would be on the rim somewhere? I'll see what I can do.

[JimB..]

I take it you mean the entire case seating slightly forward making it more difficult for the firing pin to reach the primer.


OK. The extractor marks would be on the rim somewhere? I'll see what I can do.

He said bullet, he meant cartridge. I was also over simplifying, it’s not possible to reliably evaluate headspace from a picture, you really need to find a gunsmith with a set of go/no-go gauges. We might see a gross problem, but it’s unlikely that you have a gross problem.

That said, the more I think about it the less I think it’s a chamber issue, the 1911 firing pin protrusion is so long that it will give a solid strike on even a very generous chamber. In the spirit of doing the easiest things first, replace the hammer spring and the firing pin return spring making sure that you get the right ones for our gun.

[slughammer]

The kimber might have a titanium firing pin. The lighter mass allows the spring to retract the titanium pin too early in the pressure curve.

(Springfield Armory used titanium to pass a drop test)

I had a 9mm 1911. It was doing the exact same thing to the primers. I solved the problem by installing a steel firing pin. Problem went away immediately.

[Peregrine]

I started a thread here about similar issues with my .223 not too long ago.

I've eliminated most of the possible causes except for the firing pin spring, and I have a couple of those on order. I'll update there when I get them in.

[GARD72977]

The pic shows the firing pin hole is to large. Have a gunsmith look at it.

[243winxb]

1911 types -The inertia firing pin doesn't stay in contact with the primer after it drives the round forward and fires the round.
The extractor stop the rounds forward movement. imo. (some say yes, some say no)

The firing pin retracts/pushed back into the slide after doing its job.

As the round fires, the case/primer are pushed against the slide/bolt face.
If pressure is high, the primer flows into the firing pin hole.

In a revolver , when the pin stays forward against the primer, the depth of the mark in the primer looks deeper and wider.
An old model revolver, with the pin on the hammer, can have hammer bounce. As the firing case hits the recoil shield, it slams the pin back. The pin moves forward again, as the main spring is still putting 25 lbs pressure on it.

May look like a double strike on the primer.