Stopping the firing pin

A

Al Nyhus

"It'll never work!"
I'm interested in hearing peoples thoughts on this little discussed, but very important, subject. Specifically:

- How should the firing pins forward motion be stopped?
- Methods/materials used to stop the firing pins forward motion.
- Benefits or downsides to different methods.

Looking foward to some good discussion. Feel free to spin off in whatever direction this takes us. :) -Al
 
Al

I am not trying to be trite, but what actually stops most of the forward momentum, and dampens the strike, is the primer its self.

If I strip the springs off of my Farley and my Stiller actions, and drop the pin into the bolt, it protrudes exactly the same amount as if everything was assembled and I let the pin fall.

That shows that the firing pin landing shoulder bottoms out in the body of the bolt before anything else hits, such as the cocking piece in the bottom of the cocking cam ramp........jackie
 
All you need to do is two measurements from the back of the bolt shroud to the back of the cocking piece. One measurement with an empty chamber and one measurement on a fired case, preferrably just after firing before the bolt is opened.
 
I just measure the indentation with a tapered point anvil for my depth mic.
bhdr0k.jpg
 
Mr. Al thanks for the question, something i have been wondering about. I'm rimfire, don't know anything about centerfire but this subject could be related to both.

It seems accepted opinion is you don't want any firing pin bounce, at least for rimfire. If you let the pin bottom at the end of the bolt and hit the rim in rimfire your going to get 2 vibrations, one from the bolt hit and one from the rim hit.

My current thinking is let the rim of the cartridge stop the firing pin. I have modified my pin so it does not hit the end of the bolt -and the rim takes all the hit.

Now for "bounce". if i could ask in your thread, is there a way to detect firing pin 'bounce"? maybe i went the wrong way? you could let the bolt take the major hit and let the primer just take enough for it to fire.
thanks! joe:)
 
Backtracking....

I guess I need to clarify my original post.

I'm not asking how to measure firing pin fall, how pins are normally stopped, etc.

But there's some work being done and some new ideas being tried in this area. Just thought some others here might be working with this, as well.

Good shootin'. :) -Al
 
Al, think about it. When you pull the trigger the firing pin hits the primer and stops right there. Without a cartridge in the chamber the firing pin would be stopped by whatever scheme the designer has used. On Rem/clones this is the shoulder on the firing pin contacting the end of the counterbore in the bolt body.

This has no bearing on the firing cycle assuming that the action has a proper amount of firing pin protrusion.
 
crb said:
Al, think about it. When you pull the trigger the firing pin hits the primer and stops right there. Without a cartridge in the chamber the firing pin would be stopped by whatever scheme the designer has used. On Rem/clones this is the shoulder on the firing pin contacting the end of the counterbore in the bolt body.

This has no bearing on the firing cycle assuming that the action has a proper amount of firing pin protrusion.
Click to expand...

Okay...I'll take one more run at this.

I know how it works. My point (evidently poorly stated..twice) was that there is work being done on other ways to stop the firing pin....ways that take the primer out of the picture as the travel limiter.

Three strikes and I'm out. :)
 
Al Nyhus said:
Okay...I'll take one more run at this.

I know how it works. My point (evidently poorly stated..twice) was that there is work being done on other ways to stop the firing pin....ways that take the primer out of the picture as the travel limiter.

Three strikes and I'm out. :)
Click to expand...

Mr. Al is it Top Secret what the "other" ways of stopping the f. pin are? seems you are hinting you know something but you ain't saying.

Who has established letting the f. pin stopped by the primer is a bad thing? thanks joe:)
 
jGEE said:
Mr. Al thanks for the question, something i have been wondering about. I'm rimfire, don't know anything about centerfire but this subject could be related to both.

It seems accepted opinion is you don't want any firing pin bounce, at least for rimfire. If you let the pin bottom at the end of the bolt and hit the rim in rimfire your going to get 2 vibrations, one from the bolt hit and one from the rim hit.

My current thinking is let the rim of the cartridge stop the firing pin. I have modified my pin so it does not hit the end of the bolt -and the rim takes all the hit.

Now for "bounce". if i could ask in your thread, is there a way to detect firing pin 'bounce"? maybe i went the wrong way? you could let the bolt take the major hit and let the primer just take enough for it to fire.
thanks! joe:)
Click to expand...

jGEE,

Here's what I did.

Fairly hotloaded 6BR, 105's at 2850 in an un-bushed 700. Stock firing pin/spring etc.... 15lb rifle.

First I lightly taped several objects (like BB's) to the rear of the striker. They didn't pop off in firing.

Next I stuck clay to the striker and measured it after dropping the striker WITH and WITHOUT a firing event. Mesured slightly more compression when firing VS dryfiring.

Then I stuck some small magnets to the rear of the striker, they didn't pop off.

Finally I dared to fire the gun with my finger firmly pressed to the rear of the bolt, trying to follow the striker down with finger pressure.

All this means little but IMO if the striker rebounded very much I'd have noticed.

If I'd blanked a primer I'd have bruised my finger! :eek:

FWIW

al
 
One thing no one seems to mention about strike depth in the primer. The pressure in the chamber travels into the primer via the flash hole and that pressure drives the strike dent back out. Fred Moreo told us about the shape of the firing pin tip VS cratering and setting firing pin protrusion to .040" +- .005", golden info. BillPa's post its clear evidence of the reshaping, [rest assured he is quite aware of this] and his protrusion is at least double that depth shown. I'm no smith but have mentioned .050" for the Rem because if I said .040" they would never believe me.
 
Savage firing pins have adjustable protrusion. One fellow that I know, who used to work for Savage, sets his at .035. I have never done this, but if one primed a tight case, and fired the primer, one might be able to compare dent depth with a fired primer from a round that had been loaded and fired in the usual manner. This might yield some information about whether the dent is made shallower by pressure coming back through the flash hole during firing.
 
Have you guys NEVER had a misifre or intentially tried a killed primer? Its visibly obvious the dent is much deeper.
 
I have faced the stop shoulder of an OEM Rem firing pin to cushion the fall by inserting a couple different materials to include a 7000series aluminum,a 460 brass,& a delrin washer pressed on the tapered pin fwd of the faced stop shoulder to act as a buffer.
The alum,brass,delrin washers were installed one at a time not stacked one on top of the other.
I faced/grooved the stop shoulder once to install an O ring also.

I don't have the instrumentation to verify any conclusions.
 
German Salazar said:
The question still remains - how will performance be affected by a definite stop on firing pin travel that would cause the pin to stop somewhere short of where the primer itself would cause it to stop?
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German,

Due to arthritis issues with my thumbs, I've recently started to use the K & M dial gauge primer seater in a (successful) attempt to reduce the occasional low shot at long distances I attributed to over or under seating the primer. An interesting observation I've made since is that an occasional primer has a top of cup to foot of anvil measurement better than .010" different from the average. Maybe these have been the ones I screwed up with, maybe not.

But what would be the ignition outcome for such a primer perfectly seated if you were to arbitrarily stop the firing pin? I suspect that it would be significently more critical than it would be with a free moving pin.

Would it be worthwhile to take a depth mike to your next batch of loads & check how consistently they seat below the head of the case?

John
 
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I observed this today

PEI Rob said:
Have you guys NEVER had a misifre or intentially tried a killed primer? Its visibly obvious the dent is much deeper.
Click to expand...

I had a dud primer and I noticed that the dent in the primer was quite a bit seeper than the ones that had fired.

Adendum:

Several years ago Randy Robinette stated on here that he had enlarged the flash holes in his Lapua 30 BR cases because he had noticed that the Remington BR cases he was using gave better accuracy than the Lapuas. As some may know, the Rem's have a large flash hole, by Lapua standards. I had seen people talk about the extra pressure the small hole provided, yada yada yada and none of it was a fact. I opende mine up to the Remington size and continue to do so.
 
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