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Firing pin fall --a discussion

No because that would make the firing pin cock on close. If you move the trigger rearward you gain pin fall, but then if you time the cocking piece to the new trigger sear location, you are right back to reduced pin fall. When I make the firing pin cock farther to the rear I gain pin fall regardless of trigger hanger position and whether I time a trigger or not. No matter what, you gain pin fall.

I’ve only done this modification on actions that use an identical ignition system as the Rem 700 so can’t say if it works on everything. I know Alex has done it on quite a few different custom BR actions and I gathered from talking to him that it’s not an easy task on some of the other ignition systems out there. Which is a big reason he talks to action manufacturers about making everything perfect right out of the box. Not fun spending a lot of money on a custom action then having to tear it apart to make necessary changes for proper timing and ignition.

I did this on a Kelby Atlas as well. When they first came out they had good pin fall but significant cock on close with the BnA trigger I like. Measurements showed me the Atlas had room for improvement so the modification would work. With the BnA trigger timed on the Atlas I fell down to around .218” pin fall. After modifying for more pin fall i got it back up to .242”. I talked to Ian at Kelby about my findings and I’m sure others did as well. I heard Kelby has done some modifications of their own to the ignition system to provide good trigger timing with proper pin fall. I haven’t tried one of the latest Atlas actions yet so can’t actually confirm that personally but hats off to Kelby for listening to input if this is true.

On my BAT HR, the BnA trigger is perfectly timed and has excellent pin fall right out of the box. No need to touch it whatsoever. Smooth as melted butter ;)
I talked to Ian yesterday, he told me they were making changes to their ignition system to maintain .250+ firing pin fall. I agree, Kudo's to the Kelbly's.
BAT Machine has bee listing to the smiths for some time, much respect for them also.
CW
 
Firing pin fall is measured on an empty chamber. The front of the firing pin flange is what stops the pin fall when dry firing on an empty chamber. With a Remington style striker assembly, I believe that one would have to remove material from the front of the flange in order for the pin to fall farther. This would also require modifying the pin tip for a couple of reasons. First of all the taper behind the tip diameter might contact the bolt, keeping the pin from falling to the point where the front of the flange contacted the inside of the bolt. Secondly the increased fall would increase pin protrusion in direct proportion to the increase in FP fall. The usual standard for pin protrusion is about .055 but when the pin falls on a live primer in a properly sized case it is stopped by the primer, well short of that. You can make your own measurement on a Remington by comparing how far down in the shroud the back of the cocking piece is after dry firing, and comparing it to how far down it is after firing a live primer. With that difference and the actual measured FP protrusion, you can see how much of the excess protrusion might be, keeping in mind that you do not want the front of the flange to bottom when actually firing a round. Years ago Bob Greenleaf (retired engineer from Savage) toldme that he set his personal rifles for a FP protrusion of .035. Bob was with the company for 25 years. For those who are not familiar the model 110s had adjustable FP prutrusion. To get a better understanding of the whole protrusion thing, Imagine a pin that had a tip that was so long that it was flush with the bolt face with the action cocked, which would make the protrusion equal to the fall. In that case, the pin would only be able to fall the distance to the primer from the bolt face plus the depth to which it deformed the cup. You need to use an empty case for these tests because I believe that in the case of a hot load the primer dent may be pushed back a bit. from where it would be if the primer alone was fired. Excess protrusion actually reduces the effective pin fall and reduces the energy delivered to the primer.
I have previously read something similar to this, I think it might have also been one of your comments. After reading it I decided to use two measurements for firing pin travel. I decided to use the distance from cocked to primer contact as one measurement and firing pin protrusion as the other. I want .200" of travel before primer contact and .055" of protrusion. I prefer the feel of a little bit of cock on close. I've only done a couple of actions but neither of them has over .020" cock on close. .020" doesn't feel offensive to me.
 
One thing you most definitely do NOT want in a Rem 700 type ignition system is the cocking piece bottoming out and being stopped by the bottom of the cocking ramp. The cocking piece is only designed to load the spring, not to be used as a device to stop it. The firing pin should be stopped on the shoulder inside the bolt body.
 
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I had about .210”pin fall on a BR action….. no cock-on-close. By adding a .030” trigger hanger to the system I gained some cock-on-close (not the full 30, but some) and I gained a lot more reliable ignition system.

I think a reliable ignition has got to be the first priority?
Cock-on-close sucks, no doubt about it. Especially when you have actions that a good smith has worked their magic on to compare to. However, a small amount of cock-on-close isn’t hurting anything on the above action and the aggs are smaller because of better ignition.

What percentage of smiths around the nation know how to properly address acquiring at least the minimum pin fall and little to no cock-on-close?

I am not trying to beat up on anyone here, just shining a light in a dark place and furthering my understanding of the ignition system.

CW
If the cocking cam helix is deep enough and the closing cams are designed right timing an action is really basic stuff. When they aren't it's a lot of work and a dremel is not the right tool it has to be done on a mill or it's going to open like sh!t. I have had to fix a lot of dremel jobs. In that case your far better off with cock on close if your not going to do it right.
 
I had about .210”pin fall on a BR action….. no cock-on-close. By adding a .030” trigger hanger to the system I gained some cock-on-close (not the full 30, but some) and I gained a lot more reliable ignition system.

I think a reliable ignition has got to be the first priority?
Cock-on-close sucks, no doubt about it. Especially when you have actions that a good smith has worked their magic on to compare to. However, a small amount of cock-on-close isn’t hurting anything on the above action and the aggs are smaller because of better ignition.

What percentage of smiths around the nation know how to properly address acquiring at least the minimum pin fall and little to no cock-on-close?

I am not trying to beat up on anyone here, just shining a light in a dark place and furthering my understanding of the ignition system.

CW
What is the firing pin tip diameter of your action?
 
I have about .228" pin fall on my Panda, i emailed Kelbly's and they recommended a .030 hanger which i purchased and installed, i now have .228" pin fall. No change.
 
I had about .210”pin fall on a BR action….. no cock-on-close. By adding a .030” trigger hanger to the system I gained some cock-on-close (not the full 30, but some) and I gained a lot more reliable ignition system.

I think a reliable ignition has got to be the first priority?
Cock-on-close sucks, no doubt about it. Especially when you have actions that a good smith has worked their magic on to compare to. However, a small amount of cock-on-close isn’t hurting anything on the above action and the aggs are smaller because of better ignition.

What percentage of smiths around the nation know how to properly address acquiring at least the minimum pin fall and little to no cock-on-close?

I am not trying to beat up on anyone here, just shining a light in a dark place and furthering my understanding of the ignition system.

CW
Ignition on a rifle for 1000 yards can make or break a gun. Seen some where a weak firing pin spring absolutely destroyed accuracy. Matt
 
What we need is a standard in 'dynamic strike force' (DSF), for best precision as measured on target.
It would be possible to do,, Jackie mentioned that his 30br was best with .250" PF with 24Lbs of static spring force. That means nothing of DSF, but with that setting, DSF could certainly be measured at a standard distance from bolt face (maybe ~10thou).
Combine adjusted to DSF with a standard in pin diameter, primer, primer seating, and headspace to replicate optimum with any action.

Of course the difficulty would be in developing such a standard, given different primers, and putting it out there in a way that reloaders can adopt. Kit form.
It makes sense IMO for an action maker, who shoots 600-1kyds, to do this. But it could be anyone with the resources, and inclined to leave a positive legacy.

A go-gauge fitted with an instrumented dummy primer. The measure captured by DAS sampling and fed to laptop graphing. Adjustments(one form or another) to PF and spring would be made to match desired DSF.
 
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Kelbly hangers only go one way, theres a notch for the cocking piece that goes to the rear. You probably just need a .050"
 
If the cocking cam helix is deep enough and the closing cams are designed right timing an action is really basic stuff. When they aren't it's a lot of work and a dremel is not the right tool it has to be done on a mill or it's going to open like sh!t. I have had to fix a lot of dremel jobs. In that case your far better off with cock on close if your not going to do it right.
This ^^^^^^^ ;)

Good shootin' :) -Al
 

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