M14 Firing pin bridge saftey test method

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Savage

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I have decided to post the outlines of a safety test that will allow a user to check the bolt firing pin timing issues ,I did not make this test up but rather I am passing it along to you .

It is a rather simple test dissamble your rifle remove the reciver from the stock then remove the OpRod ,spring and guide .Leaving the bolt in the rifle, next place your rifle on your lap with the right side of the reciever facing up .Place your left thumb over the rear of the bolt depressing the firing pin while the bolt is forward in battery. Next place your right hand thumb over the bolt roller and and lift the bolt roller till you meet resistance and look at the amount of contact the bolt has also look at the bottom of the bolt this is where you measure the clearance .You can use pennies or dimes to measure the clearsnce of the gap a Penny measure an average .060" each and the Dime measure .045" I conducted a test on 3 M14 rifles I have and the 2 M1 Garand's i have I decided to check the bolt firing pin timing and to my amazement it variies quite a lot
The 2 M1 Garands both Springfields gave a a Distance of .110 "
The M1A gave a distance .115" .
The Norincos gave a me the biggest difference in that one was .156" and the other was .197":eek:
 
So the further you can rotate the bolt before the firing pin is restrained by the channel, the further out of battery the bolt can be and still drop the firing pin?
 
Savage said:
I have decided to post the outlines of a safety test that will allow a user to check the bolt firing pin timing issues ,I did not make this test up but rather I am passing it along to you .

It is a rather simple test dissamble your rifle remove the reciver from the stock then remove the OpRod ,spring and guide .Leaving the bolt in the rifle, next place your rifle on your lap with the right side of the reciever facing up .Place your left thumb over the rear of the bolt depressing the firing pin while the bolt is forward in battery. Next place your right hand thumb over the bolt roller and and lift the bolt roller till you meet resistance and look at the amount of contact the bolt has also look at the bottom of the bolt this is where you measure the clearance .You can use pennies or dimes to measure the clearsnce of the gap a Penny measure an average .060" each and the Dime measure .045" I conducted a test on 3 M14 rifles I have and the 2 M1 Garand's i have I decided to check the bolt firing pin timing and to my amazement it variies quite a lot
The 2 M1 Garands both Springfields gave a a Distance of .110 "
The M1A gave a distance .115" .
The Norincos gave a me the biggest difference in that one was .156" and the other was .197":eek:
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Hi Savage, thanks for the thread. That's some interesting info. I have some questions just to clear my unserstanding a bit...

1. Is the penny and dime thickness of .45 to .60 the safe operating range for bolt/firing pin timing on the M14, Norinco M305, etc? Should any larger than that be a consern?

2. Is it the firing pin itself that makes the difference in distance? If so, are aftermarket firing pins made longer so it can be custom fitted to the bolt to get a safe operating range?
 
Savage,
I don't have a M14 to measure anymore, but if I understand your post correctly any increase in the measurement reduces the lug contact area by the same amount? Double seems like a lot. If the bolt on my old rifle is rotated to the point of the fracture on the recess what would the measurement be?
I suspect that this test could have saved me some grief.
 
Sticky!

Nice explanation Savage.

This thread should be a sticky once the fine tuning is done.

Hungry here: I'll be happy to sticky it once someone finds a credible reference to such a test. I sure as heck ain't THAT credible
 
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this safety check is best performed on a stripped receiver, a clean bolt and a set of proper firing pin protrusion guages used while rotating the bolt through it's locking phase.
In the absence of that there is the following recommended method of performing a similar test.
if you are a reloader or know one.....1) size a case so that a 'stripped' bolt drags a case at the approximately 50% locked position. ie:bolt lugs engaged to receiver lugs at 50%
2) take the case and fill the primer pocket with bedding compound and wipe flush.
3)chamber the case, install and rotate the stripped bolt to the 50%locked position
4)drop in and align the firing pin
5) measure the space between the receiver bridge primary retracting surface and the flat front of the firing pin tang with 1 thou increment guage strips.

this test is best performed by an M14 specialized gunsmith with the appropriate guages and armorers reference material to compare findings.

Interesting test outlined above by Savage..... any reference for the source of that info? Going to check that out on my rifles and see what it tells me.
 
scanner said:
Hi Savage, thanks for the thread. That's some interesting info. I have some questions just to clear my unserstanding a bit...

1. Is the penny and dime thickness of .45 to .60 the safe operating range for bolt/firing pin timing on the M14, Norinco M305, etc? Should any larger than that be a consern?
Click to expand...
I put those items and the measured thickneses to help someone to do there own check .This will vary for each rifle ,Is a larger distance a concern ?Yes it is if you are reloading and you are not using a properly set up full length or small base resizing die as well not checking the OAL of the brass casing,
This test also is important as well in the event of Hammer follow were to occur this gives you an insight of what might occur.It also gives credence to what others have said about tuning and filing of the triggers
While the firing pin bridge block is a safety device the ultimate safety device is you the user .The bridge while a good idea but is flawed as it is a rather complicated machining step and recent testing indicates that some manufacturers do not see this as a problem.Gven the fact that this rifle has apparently had no issue shooting factory ammunition

scanner said:
2. Is it the firing pin itself that makes the difference in distance? If so, are aftermarket firing pins made longer so it can be custom fitted to the bolt to get a safe operating range
Click to expand...

Yes the firing pin tail is important in the opration of the bridge it is not the firing pin that sets the distance it is the bridge block . As far as I know all firing pins are the same length I know I could be wrong but I am unaware at this time .
 
Dogleg said:
Savage,
I don't have a M14 to measure anymore, but if I understand your post correctly any increase in the measurement reduces the lug contact area by the same amount? Double seems like a lot. If the bolt on my old rifle is rotated to the point of the fracture on the recess what would the measurement be?
I suspect that this test could have saved me some grief.
Click to expand...

I agree it could have and as well because the bolt rotates into battery any amount that the bolt is not into full battery also affects the headspacing by increasing it
 
Okay, so I've always had an a want for an M14.

Should headspacing be checked in only shooting factory ammo? If yes, any "general" ammo specs to look for off the shelf?
 
I've had success shooting all this ammo out of my Norc M14's AND USGI M14's with much larger headspace than ANY of the Norinco M14's.... EVER!

* Milsurp 7.62mm : Brazilian, Portuguese, South African, Lake City, and IVI (Canada)
* Winchester white box .308 (147 gr. Ball)
* Remington UMC (Yellow Box) 147 gr Ball
* Winchester PowerPoints

So before people start with all the firing pin tang and bridge measurement practices (which I totally misunderstand ... maybe it's March break or maybe I'm stupid) do just like Savage, 45ACPKing and I will reinforce...

* Observe proper handloading techniques
* Put away all pistol powders from the reloading bench (avoids kaboooms)
* Work with ONLY ONE rifle powder type on the bench at one time
* Seat all you primers the way the manufacturers tell you (read the manuals), make sure they ain't protruding above flush!
* Always feed yer ammo from the magazine (5 rounder or 5/20 rounder or 5/10 rounder)
* Never chamber a loose round and then let the bolt fly forward (begging a slam fire)
* Keep yer M14 or M1 well lubed

All this advice is well referenced! Anything else, I out of my expertise/ experience!

These are battle rifles with battle rifle chambers (read: designed to be large) so get used to it.

You think a tight (read : National Match dimensions) is gonna decrease the likelihood of a slam fire ? Suprise...you just raised the probability of a slam fire with a tight chamber.

Avoid slam fires by practicing the advice I mentioned above. This ain't news among the M14 competitors! And you won't have yer #### fall off!

I've never ever experienced a slam fire and I never will (safe practices from above...).

You newer fellas to the M14 addiction: If you are worried about a slam fire then sell your M14 and buy a bolt/lever/muzzleloader/AR15/bow/crossbow/Autococker Paintball gun/ Smart Parts ION, or a slingshot.

I'm getting tired of this subject hijacking our M14 community!
 
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looks like my rifle is around the .165" mark.... should I be concerned?

zoomed.jpg
 
Goose25 said:
looks like my rifle is around the .165" mark.... should I be concerned?

zoomed.jpg
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No it is quite safe to shoot .I posted the test so that you the owners can at least understand the issues of firing improperly resized reload ammunition in there rifle's and the potental for problems

Like Hungry and everybody else is saying be carefull when reloading for the M14 use caution and you will enjoy shooting your Rifle for a very long time
 
I'm getting tired of this subject hijacking our M14 community!
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That's a bit of of a stretch. The M14 has a safety feature that is supposed to prevent out of battery firing caused by anything. Anything includeing battle field crud, mud, damaged ammo, wrong ammo or screaming hot rifles. The action has to close all the way, or it doesn't go bang and GI Joe doesn't eat his bolt. Norinco dropped the ball in this case, maybe in others.


Hungry here: You are making a claim here about Norinco dropping the ball. Let's get some evidence to prove this because I'm too stupid to know any better. We've been beating this issue to death since all kinds of people are offering their 2 cents worth here, and I'm flooded with PM's from newbie M14 owners (in the past 3 days) asking whether they should sell their Norinco M14's they have just bought. By all means prove it and we can move on from there and sue the Communists. Please, let's work with the facts (documented, researched, and published), after all, that's all I do in my day job (as a teacher).


That's an hell of a safety issue, and apparantly there is a test to confirm that the condition exists or doesn't. You should welcome that in your M14 community.

Hungry here: I'll welcome all the safety we can muster, but let have the professionals make that call. I ain't one of them.
 
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Ok --anyone with a GI M-14 or M1A please answer this:

When pulling back slightly and slowly on the cocking rod of my M305 on a fully cocked M-305, to the point before the lugs have even begun to rotate into battery - I pull the trigger and the hammer does drop! It actually drops for a length quite a bit before beginning to rotate into battery!

I tried this on my Russian SKS and it will not drop until until battery.

All other tests (hammer drop, hammer follow...) of my rifle prove it to be ok in all other respects.

I was wondering if this dropping of the hammer early happens with the GI M14 or Springfield M1A?

Cause as I see it right now -- the M-305 being able to drop the hammer before even approaching battery to me is a real issue. Unless the M-14 was the same.

Also are the trigger groups the same betwen the Springfield version vs. the Norinco copy?
 
I don't think its an issue. You pull the trigger and the gun fires on the closed bolt. You can't drop the hammer again until you let off the trigger. By the time that has happened, the bolt has closed again.

farshot said:
Ok --anyone with a GI M-14 or M1A please answer this:

When pulling back slightly and slowly on the cocking rod of my M305 on a fully cocked M-305, to the point before the lugs have even begun to rotate into battery - I pull the trigger and the hammer does drop! It actually drops for a length quite a bit before beginning to rotate into battery!

I tried this on my Russian SKS and it will not drop until until battery.

All other tests (hammer drop, hammer follow...) of my rifle prove it to be ok in all other respects.

I was wondering if this dropping of the hammer early happens with the GI M14 or Springfield M1A?

Cause as I see it right now -- the M-305 being able to drop the hammer before even approaching battery to me is a real issue. Unless the M-14 was the same.

Also are the trigger groups the same betwen the Springfield version vs. the Norinco copy?
Click to expand...
 
Valid and good point Grizzley....

Unless tho a round was jammed very proud of the chamber and you pulled the trigger and the pin was able to hit the primer.

Then you would get the Dogleg Event.
 
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Hungry here: You are making a claim here about Norinco dropping the ball. Let's get some evidence to prove this because I'm too stupid to know any better. We've been beating this issue to death since all kinds of people are offering their 2 cents worth here, and I'm flooded with PM's from newbie M14 owners (in the past 3 days) asking whether they should sell their Norinco M14's they have just bought. By all means prove it and we can move on from there and sue the Communists. Please, let's work with the facts (documented, researched, and published), after all, that's all I do in my day job (as a teacher).
Click to expand...


Savage has already proven that my old rifle (Now his) will drop the firing pin on a live primer before the bolt is completely closed. I personally had a ringside seat at the event so need no further proof. Since the parts of the rifle are no longer mine it is out of my hands anyway.You don't have to give any answer to your flood of PMs. Why would you think you do?
What does teaching have to do with this? My mother was a teacher, my wife is a teacher. Neither know anything about guns. Didn't know it was a requirement.
Autoloaders aren't supposed to fire before the action is securely closed. Neither are bolt-actions or lever-actions. My truck isn't supposed to start except in Park or Neutral. An elevator isn`t supposed to go up or down with the doors open. These things are worked into the designs, for the safety of the operator and the equipment. The design safety feature on my rifle did not function as designed. Maybe it`s the only one, maybe it isn`t.
I couldn`t care less about sueing the communists, or anyone else for that matter. What could I possibly hope to gain from that.
 
Let's do this... Any M1 Garand owners out there? Give Savage's test a try and get back to us....

Yes, I am a teacher and I have the emotional scars to show. I am pretty dopey these days, March break is starting. :rolleyes:

As teachers, we cannot teach anything unless it's documented and research based. So I'm being advised to advocate a rifle test that the NRA publications have not mentioned anything about (yet). I cannot write the Computer Science Curriculum for the Province of Ontario, but I have contributed much input to Dr. Rick Holt , the author of TURING Programming Language at the University of Toronto. The material I teach (we teachers deliver) MUST be sourced back to that document/text/ material. Just like the material delivered at my M14 Clinics: It's all sourced BACK to the NRA Publications gathered over 40 years ago and then printed. I ain't inventing this shzt. Let's do this then....

Everyone with M14's do this test and if they fail this test that we on CGNutz came up with, we should get our money back? 'Cause we said so?

Out of battery firing has happened before and it was not done on Norinco M14's but M1A's and Garands, too. We ain't the first ones (Norinco M14's) to experience this incident. I'm just not convinced that this test is the be all and end all, yet.... Maybe I'm wrong!

Jerry Kuhnhausen is an authority on this issue. Let's let his research and engineering be the final arbiter(sp?) decider of this issue once and for all. :evil:
 
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I already tested my 2 M1 Garands .Both have .110" more travel into Battery this really translates into may be .005 " actual increase in headspacing .This is not a problem when shooting factory ammunition or properly resized reloaded ammunition . The problem occurs when people get complacent in both maintenance of the rifle and reloading the cartridges .
As far the the transmission have a neutral safety switch to prevent people from starting it in gear it is not so much a safety as it is to stop stupid people from starting it in gear.
Have we really become so reliant on mechanical safety's that we have forgotten the that we should be the ones thinking of safety and not the other way around
 
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