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Old January 4, 2014, 01:42 PM   #1
chris in va
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Garand firing pin question

To the point, I'm paranoid about out of battery firing or slam fires in my Garand after witnessing the event with an M1 carbine.

Is there such a thing as a firing pin retractor spring that can be added to my rifle?
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Old January 4, 2014, 01:56 PM   #2
101combatvet
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Breaking down the bolt and cleaning it once in a while should prevent that from happening.
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Old January 4, 2014, 03:52 PM   #3
Merad
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The Garand bolt is supposed to be designed to prevent out of battery firing (except slam fires, obviously). IIRC the hammer can't hit the firing pin unless the bolt is locked, so it will waste most of its energy pushing the action into battery.
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Old January 4, 2014, 08:51 PM   #4
Dfariswheel
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A retractor spring would probably cause more problems than it could possibly cure.

Many rifles have free-floating firing pins, such as the M1 Rifle, M1 Carbine, AK-47/74, AR-15/M16, etc.

The design is such that the firing pin is deliberately made so light, that it doesn't have the mass to cause a "slam fire" unless the pin has corroded or otherwise stuck in place so firmly it's jammed forward.

As above, all free floating rifles also have some system to prevent the firing pin from contacting the primer until the bolt is locked.
These rifles may leave a tiny mark on the primer, but the combination of the light pin and the system to prevent the pin from touching the primer until bolt lock won't allow enough force to come even close to firing the cartridge.

The situation is, if the rifle is in safe operating condition and the firing pin is serviced regularly to insure it's free to move, no firing pin spring is needed or even desirable.

The vast majority of cases of "slam firing" M1 Rifles are due to too-light trigger jobs that allow the hammer to "jar off" when the bolt closes, using reloaded ammo that has primers that aren't seated to full depth, or rifles that are badly worn or otherwise defective and the firing pin interlock system is not working correctly.
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Old January 4, 2014, 10:37 PM   #5
jrothWA
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get a copy of Kuhn hausen's book of the

M1/M14/M1A for better understanding the floating FP and the inspection points on it.
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Old January 4, 2014, 11:38 PM   #6
Slamfire
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This is what the Italians did to reduce the risk of a slamfire with their BM 59's:

A Garand shooter had Roland Beaver do this to his M1


This information is from 2006 so I don't know if the phone or email is current.

Roland Beaver
Old Corps Weaponry
1127 Highway 64 East
Bald Knob, Arkansas 72010
501 724 6388
rfbeaver@centurytel.net

Quote:
after witnessing the event with an M1 carbine.

I am interested in the details of the slamfire in the M1 carbine. Was it with reloads, did it slamfire in battery or out of battery?


Any ideas that Garands/M14's don't slamfire is fallacious. The firing pin is always inline with the primer, it is totally free floating till the moment of cam down, and the firing pin retraction cam (receiver bridge) does not fully retract the firing pin. I have tested three stripped Garand receivers and the tip of the firing pin protrudes from the bolt face (perhaps only thousands at the start) the entire cam down cycle. Prior to hitting the receiver bridge the firing pin is totally free floating and able to rebound off the primer.

As a test you can run in your own Garand, here the firing pin is fully forward, sticking out through the bolt at 0.06" of an inch, and this is when the firing pin tang first touches the receiver bridge. For almost four inches of prior travel the firing pin is fully able to rebound off the primer.



The idea that only high primers and worn out rifles slamfire is something created by the Ordnance Department and was repeated by retired Ordnance Department Employees in the American Rifleman. It is a total sham. They were hiding the inherent design faults of the mechanism they designed, manufactured, and issued. The Garand mechanism will slamfire in battery and out of battery given a sufficiently sensitive primer. You can google slamfires for every semi automatic rifle with a free floating firing pin and you will find a slamfire report. (Except roller bolts) The Garand mechanism is an early semi automatic and does not have safety features that later designs have, and this mechanism has the most out of battery slamfires of any mechanism. In fact, I have not found any out of battery slamfire reports for any mechanism other than those built using the Garand mechanism. This includes M1 carbines, M1a's, and mini 14's. All of these mechanisms are totally dependent on primer sensitivity to prevent in battery and out of battery slamfires.
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Old January 5, 2014, 06:13 AM   #7
Orlando
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Just curious were do you get the info that the BM59 has a firing pin spring? I have never seen a spring in a BM59 bolt before

To the OP:
You are worry about nothing . The Garand , M1A ,M14, AR15,BM59, etc, etc all have the same floating firing pin. Its not a issue with good Mil Spec ammo
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Old January 5, 2014, 08:47 AM   #8
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I agree with Slamfire as I did the test on my M1 and M1 carbine and am convinced.

The bridge only protects the rifle against slam fire during, or slightly before, the bolt cams down in the receiver. If the cartridge stops before that, because of obstruction or what not, the firing pin will strike the primer and out-of-battery slam fire is possible. Military spec primer should therefore be used.

A few things to add
1. The firing pin is not quite inline with primer all the time. The round needs to come out of the magazine and go into the chamber about half way before the primer lines up with the firing pin hole.

2. It is a push-feed action. The cartridge stops and the extractor snaps over the cartridge's rim, then the firing pin can reach the primer. This decelerates the bolt gradually and lessens the free floating firing pin's energy.

-TL

Last edited by tangolima; January 5, 2014 at 10:11 AM.
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Old January 5, 2014, 11:40 PM   #9
chris in va
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Thanks guys. I've been using CCI LRP, might switch to the #34's. no issues yet but always good to be safe. I hear Tula LRP are pretty hard too as my CZ carbine doesn't set off Wolf ammo reliably.
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Old January 6, 2014, 01:05 AM   #10
James K
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FWIW, the M1 carbine bolt has a ridge part way around the rear end that won't allow the hammer to reach the firing pin unless the bolt is locked. Some commercial bolts lack that feature.

Jim
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Old January 6, 2014, 04:24 PM   #11
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FL size, flush primers & replace FP occasionally

Do a good job of full length sizing your brass, such that it very freely chambers. Doing anything else risks slam fires. Until I encountered Greek HXP brass, I had never found any .30-'06 brass which required a small base sizing die to chamber freely, but HXP does in my NM conditioned Garand.

I shot M1 and M1A rifles for many years with Federal rifle primers, probably the most sensitive primers out there. Just make sure they are slightly below flush, and you will have no problems.

Every several thousand rounds, replace your firing pin.
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Old January 6, 2014, 08:47 PM   #12
tangolima
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I tried WLR primer. Primer seated slightly below flush alright. It slam fired in my M1 the first time I test fired the load. Slam fire never happened after I switched to Tula NATO.

-TL
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Old January 6, 2014, 10:02 PM   #13
James K
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If "slam fire" is defined as firing out of battery or firing as the bolt closes (not "doubling" due to a worked over trigger or trigger finger reflex), the most common causes are high primers and sensitive primers. The M1 rifle was designed and intended to be fired with government issue ammunition, made to rigid specs, not with reloads tossed together by civilians. With GI ammo, slamfires are very rare (not unknown, but very rare). That does not mean that users of the rifle cannot reload, but they must understand that ammo for the M1 (and other semi/full auto rifles) needs to conform to the specs for that rifle more than ammo for, say, a bolt rifle. As to the view of that the rifle design is defective and a vast evil conspiracy has covered up that fact, I have expressed my ideas on that theme several times and won't do so again here.

If the ammunition used is GI, made for the M1, or loaded to GI specs, including primer hardness, slamfires should be no problem.

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Old January 8, 2014, 12:13 PM   #14
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Quote:
Its not a issue with good Mil Spec ammo
Quote:
If the ammunition used is GI, made for the M1, or loaded to GI specs, including primer hardness, slamfires should be no problem.
I suppose there are exceptions to every rule.

My "new to me" DCM Garand went grenade on the first trip out, using issue LC69 in a match back in the mid 80's. I had had a couple of "doubles" in the rapid fire strings, and I thouhgt since the gun was new, it was just me and not the gun. After things went south, and my brass was recovered later, those that had doubled, had obviously fired out of battery, as the necks were blown out. Lucky for me, the one that cut loose, was during the slow fire string, and I was single loading.
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Old January 9, 2014, 08:08 PM   #15
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Quote:
1. The firing pin is not quite inline with primer all the time. The round needs to come out of the magazine and go into the chamber about half way before the primer lines up with the firing pin hole.
I agree, unless you put a round in the chamber and drop the bolt! Really what I was thinking of was of the SKS and FAL designs. With these designs the bolt face is at an angle to the cartridge base until lockup. Only when the locking mechanism engages does the breech face rise to perpendicular and the firing pin is in line with the primer.

These mechanisms have slamfires but all the accounts I have seen, they are in battery. Murray’s offers a firing pin spring for the SKS rifle. Besides the benefits he claims, this spring will reduce the impact energy of the firing pin as it rebounds off the firing pin.

http://www.murraysguns.com/sksown.htm

Just look at this insanely dangerous video by Murray. Murray has fixed the SKS firing pin so it is all the way through the bolt face and the SKS goes full auto. The slamfires are in battery due to the titling bolt safety features Sergei Gavrilovich Simonov put in this mechanism. Without them, this rifle would have had an out of battery slamfire. In a Garand type mechanism this would create the perfect conditions for an out of battery slamfire.

http://www.youtube.com/watch?v=xj3QtnUWCwQ


If “high primers” were anything but misdirection, you would expect to find the same percent of out of battery slamfires with AR’s, HK91’s, etc, as you do with Garand mechanisms, and yet, only M1’s, M14’s, M1 carbines, Mini 14’s have out of battery slamfire reports and they have reports of both with factory ammunition. As CCI has said, high primers are the most common cause of misfires! Unless the anvil is firmly seated and the primer cake pushed into the anvil, the primer will misfire.

The best design I have seen to date (I have not seen all!) is the roller bolt mechanism. Vorgrimler designed a very safe and simple mechanism. Based on an examination of this mechanism I cannot see how it could ever have a firing pin induced slamfire. I do not see how it can have an out of battery slamfire as the firing pin cannot protrude through the bolt face until the rollers are in battery. The firing pin spring is extremely stiff, you just have to try to compress it to figure out that firing pin is not going to be floating inside the bolt. To date I have not found one report of a slamfire with this mechanism and I consider that remarkable.










It is apparent that the Garand mechanism slamfired with factory ammunition from its earliest day. This is a picture of the rare round Garand firing pin. This firing pin is rare because it was replaced in the early 40’s and it had to be due to slamfires due to its weight.


The pictures below show the scalloped Garand firing pin, the later M14 firing pin and the M1 Carbine firing pin.






The M1 carbine was the first of its class and if you look at the primer sensitivity of 30 Carbine primers, the average ignition drop height requirement is much higher than that of 30-06 primers. That is why the Army was able to use a heavier round firing pin in the carbine, nether the less, M1 carbines slamfire, and like Garands/M14’s they also slamfire out of battery as well as in battery.



Quote:
2. It is a push-feed action. The cartridge stops and the extractor snaps over the cartridge's rim, then the firing pin can reach the primer. This decelerates the bolt gradually and lessens the free floating firing pin's energy.
I don’t know how much the extractor decelerates the bolt. It may make a difference but too strong of an extractor and the mechanism would never lock up in battery. I believe adding a firing pin spring, exactly as the Italians did and Roland Beaver does is an excellent idea in reducing the inertia impact of the firing pin. More than any other design, the Garand mechanism relies on primer sensitivity to prevent slamfires as there is not a positive firing pin block in place nor is there anything to prevent the firing pin from touching the primer once the round feeds into the chamber.

Primer sensitivity is very important which is why the military specified less sensitive primers for their mechanism. What makes a “mil spec” primer different from “commercial” primers is that on the average they are less sensitive. Primer sensitivity is a great unknown in the shooting community, but if you spend enough time researching this topic at DTIC you can learn something. By design there are various technics which can make primers more or less sensitive. One of which is the hardness of the cup. This can be seen in this DTIC report: Finite Element Modeling of Primer Impact to Understand the Dynamics of Misfires http://www.dtic.mil/ndia/2011ballistics/12080.pdf Primer cake is a mixture, the mix of ingredients makes a difference, the type of styphnate used will make the primer more or less sensitive. Federal uses basic styphnate which is the most sensitive of the styphnate isomers, Winchester primers use normal styphnate.

Primers vary by sensitivity by lot and within the lot. There are requirements that primers ignite given certain impact energies, the “all fire” level is the level that all primers must ignite, and there is a “non-fire” limit, a low energy input at which no primer ignites. There are lots of different primers for lots of different devices, they all vary in sensitivity and operational requirements. You can get a good glimpse of what these are in this document: PERCUSSION PRIMERS, DESIGN REQUIREMENTS http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA092511 I have found raw primer data on DTIC and it is absolutely frightening to find primer data that indicates that primers ignite all the way down to the “non-fire” limit. I forget just how many primers, in the data, were tested at the lowest energy input, might have been 30, might have been more, but at least one ignited. There are such things as “overly sensitive” primers and that is something that cannot be detected by visual techniques.

I have found other reports that show that small differences in the amount of primer cake in the cup make a difference in primer sensitivity. Less made the primer more likely to go off, which was counterintuitive. Off center primer hits were less likely to make a primer ignite.

The absolute worst case scenario is a long or tight case with a sensitive primer. This is a perfect storm for an out of battery slamfire in this mechanism. Unlike other mechanisms in which the firing pin is fully retracted before cam down, the Garand mechanism only retracts the firing pin at cam down, and the firing pin is never fully retracted. In my experiments with Garand receivers, there was always some firing pin protraction during cam down.


M14’s have been slamfiring since the day they were made. Estate sales are wonderful things, I have a paper copy of this report. The Army was testing production models of H&R’s and SA’s for dimensional part compliance, (part interchangeability), such things as the thickness of the chrome coatings were measures, rifles were reassembled after gauging and underwent endurance testing.


USATECOM Project No 8F-3002-04, Comparison Test of rifles, 7.62 MM, M14 Manufactured by Springfield Armory and Harrington and Richardson Arms Company. Author G. E. Hendricks, July 1963.


At round 5271 a Springfield Armory M14 went off out of battery, with military ammunition. The report states:

One rifle fired when the bolt was in the unlocked position causing breakage for the firing pin, extractor, bolt roller, ejector, and stock. The magazine split, causing the magazine floor-plate spring and 12 rounds of ammunition to be ejected against the bench rest from which the rifle was being fired. The case ruptured and several pieces of brass were found in the area. A broken part of piece of brass perforated a cardboard box with was position between the gunner and the proof director. The cardboard box was used as a brass catcher. Not all the broken pieces were found. Although no one was physically injured this is a seriously unsafe condition.”

Now I am going to ask if the military does not hide its dirty laundry, then why is this 51 year old document not to be found in the public domain?


Quote:
I suppose there are exceptions to every rule.

My "new to me" DCM Garand went grenade on the first trip out, using issue LC69 in a match back in the mid 80's. I had had a couple of "doubles" in the rapid fire strings, and I thouhgt since the gun was new, it was just me and not the gun. After things went south, and my brass was recovered later, those that had doubled, had obviously fired out of battery, as the necks were blown out. Lucky for me, the one that cut loose, was during the slow fire string, and I was single loading
I do not understand how or why these mechanisms slamfire out of battery with a factory round in the chamber and yet it happens. I can only guess that this is due to bolt bounce. I can theorize that cartridge binding will create the conditions for out of battery slamfires such as the one described above, which happened as rounds were being fed from the magazine.

I guess my horrible conclusion is that this mechanism will never be perfectly safe. Since the firing pin is never captive and because primers vary in sensitivity, regardless of what you do, there will be in battery and out of battery slamfires. What you can do, and what a reloader should do: Full length size cases and size with a small base sizing die. All sizing dies should be set up with case gauges and the shoulder of the cartridge should be set back at least 0.003", or simply size to gauge minimum. Nothing but the firing pin should hit the primer so all primers must be below the case head, 0.003" to 0.005" is best. Of course you should always use the least sensitive primers in these mechanisms. You should never place a round in the chamber and drop the bolt: always feed from the magazine or SLED. While these practices will reduce the risk of a slamfire to an acceptable level, the risk of a slamfire, based on the design characteristics of the mechanism, will always be there.

I began this journey to understand why the Army Ordnance guidance that "only high primers and worn out receiver bridges cause slamfires" was patently false after my second out of battery slamfire. I knew the Federal primers were below the case head and the receiver NOS. It was from the clip and blew the receiver heel off my rifle. Why these guys lied is very complicated. I believe it might due to the competition between the Colt AR15 and Springfield Armory M14, and I believe the later, when the M1a was the service rifle to use in NRA competition, the NRA authors hide the causes for the same reasons the NFL denigns that concussions cause brain disease. http://www.pbs.org/wgbh/pages/frontl...gue-of-denial/ Both are/were threats to the sport. It was very unethical not to provide full information to the shooting community about the characteristics of these mechanisms as ignorance leads to property damage and personnel injury. The only ethical action is to inform people about all the measures they should take to prevent slamfires.

I view slamfire deniers in the same way I view people who work for the Tobacco Institute and hand out cigarettes to children. It is not a positive impression.

Still, I continue to shoot my Garands and M1a's in competition, shot two matches in Nov and one in December with a 308 Garand. Because I understand the risks of this mechanism and feel I have done all that is humanly possible to reduce these risks, the probability of a slamfire is acceptable to me.
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Last edited by Slamfire; January 10, 2014 at 05:49 PM. Reason: grammar!
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