Norinco Poly .308 M305 (M-14) Rifles

[rdrpltr271]

Any body else out there with a Poly Norinco M-305? I just witnessed first hand a premature detonation as the rifle was going into battery, throwing the forward part of the round into the breech, and blowing a substantial amount of the bolt head back down the right hand side of the butt, fortunately just to the right of my face. My son was not so lucky, sustaining 14 minor superficial wounds about his face and eyes. My assessment is that the firing pin had somehow become jammed in the forward position, and when it picked the round and started to move it forward into the bore, it fired, well before the round was seated in the bore and it was locked into battery. Before you shoot one of these rifles, I RECOMMEND CAREFULLY INSPECTING THE BOLT AND FIRING PIN SPRING FOR SIGNS OF WEAR, FATIGUE OR DAMAGE PRIOR TO FIRING AGAIN. This rifle was being fired single shot (he forgot the magazine at home) and was on the 21st shot, so it obviously was not a hot gun, and it was factory American Eagle .308 WIN, not a hand load, AND REMEMBER TO USE EYE AND EAR PROTECTION WHEN USING ANY FIREARM TO REDUCE THE CHANCE OF PERSONAL INJURY. After I posted this on Faceplant, another fellow I know posted that a friend of his son experienced the same thing. Unable to verify the age of the rifle/handload/ammo manufacturer yet, but will try. Let me know if anyone else has experienced something similar, or are these isolated incidents?

Thanks, and keep the faith!

[tango1niner]

An M 14 type rifle should only be loaded from the magazine. With no magazine in place the bolt flies forward with more speed than when stripping a round from the mag. This extra velocity gives the floating firing pin enough force to set off primers before the bolt is completely in battery. The same is true for Garand rifles.

Good your ok...

[skizzums]

I learn something everyday. I have never even thought about it. I don't think I have ever tried shooting a round with out a mag, but I won't now

[SR420]

tango1niner An M 14 type rifle should only be loaded from the magazine. With no magazine in place the bolt flies forward with more speed than when stripping a round from the mag. This extra velocity gives the floating firing pin enough force to set off primers before the bolt is completely in battery. The same is true for Garand rifles.

Good your ok...

Correct, and +1 that you're OK.

Stay safe.

[Mosin-Marauder]

I believe this is the same way with the carbine, aswell.

Correct me if I'm wrong.

[johnwilliamson062]

One of the first things I learned at my local CMP club shoots was to never load the M-14 or Garand manually as it is likely to slam fire. Always use a clip/magazine.

I believe the CMP Stores includes a warning in the documents they include with purchases.

[Slamfire]

I am very sorry to read of your injuries and it would make a great point about slamfires if you could post pictures of the blown up rifle.

While a mechanical problem, such as a wedged or broken firing pin, could have caused you’re out of battery slamfire, I am of the opinion that is a real low probability event. The Garand mechanism has a hook on the end of the firing pin and that engages the firing pin retraction cam which positively pulls the firing pin back when the bolt opens.



Now in between opening and closing, well something could have happened, but, probably not.

In my opinion, assuming the weapon was in good mechanical shape, what you had was a sensitive primer. This mechanism, which is used in the Garand, M1 carbine, and Mini 14 has a firing pin that is not positively held back until the last 30 or so degrees of cam down. That is when the tang hits the firing pin retraction cam. Until that point, the firing pin is totally free floating and fully able to rebound off the primer. At cam down, that firing pin is still jumping back and forth because most Garand type mechanisms show a dimple on the primer of a chambered rounds, such as this ones out of my Garand:



In this mechanism, as in all mechanisms with free floating firing pins, it is all about the inertia of the firing pin and the sensitivity of the primer. Sensitive primers exist, when the inertia of the firing pin is enough to ignite a sensitive primer, what you get is a firing pin initiated slamfire. In your accident, your rifle went off out of battery. Since the firing pin is able to rebound off the primer before the lugs are in battery, the Garand mechanism is the most out of battery slamfiring mechanism on the market. It is also the most inbattery slamfire mechanism on the market, but that may be due to how many are in civilian hands. The high number of reports may be due to the number of Garands/M1a’s being used, though these rifles always had reports of in battery and out of battery slamfires in NRA competitions. This March I talked to an AMU National Champ, one who won his National Championships prior to 1995 when the AMU was using M14's. He saw both in battery and out of battery slamfires with M1a's/M14's though he could not remember the particulars. Due the increasing numbers of AR15's on the market incident reports of inbattery slamfires in AR15’s are increasing, but this mechanism has hardly any credible out of battery slamfire reports, due to the fact that the firing pin is fully retracted until cam down.

To reduce firing pin inertia impact energy I sent my Garand bolt off to Roland Beaver and he installed a firing pin spring. While it reduces the impact from the firing pin, it does not reduce the impact to zero.

The picture of this dimpled primer is out of my Garand, with the Roland Beaver bolt. That round was placed in the chamber and the bolt dropped from a fully retracted position, and as you can see, that primer was well dimpled.



When the military used this mechanism it specified a relatively insensitive primer, the Frankford #34 primer, and that primer greatly reduces the chances of a slamfire, inbattery or otherwise, but even with the least sensitive primers in cases, there is always a chance of a slamfire. This is because primer sensitive varies considerable within the lot. You can buy mil spec primers that are on the average, less sensitive than commercial primers, but that does not mean you would happen to have a particularly sensitive primer within that lot. Commercial primers are more sensitive than mil spec and their sensitivity varies by brand. Commercial manufacturers use to brag about how sensitive their primers were:



It is well known that Federal commercial primers are the most sensitive primer on the market place and are by frequency of slamfire incidents reports , the most slamfiring primer on the marketplace. You were using Federal Eagle ammunition. Federal does make a mil spec primer, but they don’t offer their large rifle mil spec primer to the public. I assume their M1a Eagle ammunition has the mil spec primer http://www.shootingtimes.com/gear-ac...glem1a_200912/. The staking of the primer does nothing to do one way or another for primer sensitivity. I don’t know if you were using M1a Eagle ammunition or the regular. The regular ammunition is going to have the commercial primer and it is the wrong ammunition to use in any gas gun because of the increased risk of a slamfire. This includes that AR10 actions and any semi automatic rifle mechanism that has a free floating firing pin. If you were using M1a Eagle ammunition, which I would like to know, it just shows that slamfires occur with the less sensitive primers. This is also assuming that Federal is adhering to their quality control standards and is not shipping ammunition with overly sensitive primers that failed acceptance testing. What we know about self regulated industries, that is industries who are responsible for policing themselves, is that self regulation is a 100 % total failure. At some point in time, the corporation ships it, even though by their own procedures, it should have been scrapped. An example of the failure of self regulated industries is the Herbal supplement industry. After testing, it was found that 80% of the herbal supplements contain no herbs at all, but instead are made of rice, beans, garlic. http://abcnews.go.com/Health/bogus-h...ry?id=28684472 In this incident it is obvious what happened was not a Quality Control failure, but fraud, but hopefully everyone understands that the behaviors are the same when industry is only accountable to itself.

Anyway for the M1a, always feed from the magazine as the act of stripping a round from the magazine slows the bolt down and that reduces the inertial impact of the firing pin. Always wear shooting glasses and never assume the gun won’t go bang when a round is chambered.

[eastbank]

thanks for the run down on the semi auto rifles and primers.eastbank.

[reynolds357]

CCI 34 is the (easiest to get) proper primer to use in the M1A/Garand.

[Slamfire]

CCI 34 is the (easiest to get) proper primer to use in the M1A/Garand.

Absolutely, as the #34 primer was the non corrosive primer that the Military specified for this mechanism:

[tangolima]

Slam fire due to sensitive primer is real, as it positively happened to me with WLR primers in my M1. Now I use nothing but military primers, CCI or Tula, for loading rifles with floating firing pins; M1, M1 carbine, SKS.

I have other semi auto rifles that have firing pin spring; ptr91 and fn49. Non-military primers have no problem.

-TL

[Slamfire]

Slam fire due to sensitive primer is real, as it positively happened to me with WLR primers in my M1. Now I use nothing but military primers, CCI or Tula, for loading rifles with floating firing pins; M1, M1 carbine, SKS.

It is always good to read personal experiences on actual slamfires as there are slamfire denialists. These are people who deign the existence of firing pin initiated slamfires, and these irrational people fall into several well defined categories. One common excuse is that they never had a slamfire or seen one, therefore it cannot happen. They falsely assume they are the sum of all human knowledge. The Federal primer denialist is another type. These are guys who use and like their Federal primers and don't want to change. Deigning slamfires is a way for them to justify their use of Federal primers, which are the most slamfiring primer on the market. Personally I don't care if they blow the back end of their receiver into their head, but at least they ought to be honest about their reasons. Another type of denialist is the CCI hater. CCI is the only American company to offer their full military primer and there are people who hate CCI, and are trying to steer shooters away from mil spec primers. If you ever read a poster claiming that mil spec primers are a "marketing gimmick", you have run into a CCI hater.


The roller bolts are extremely well designed and are only going to slamfire if there is a high primer, some abnormally sensitive primer, or if crud is piled so high on the bolt face that it contacts the primer. For high primers to go bang the anvil has to be positively seated and the gap between cup and anvil set. If either are off, then it turns out high primers are the most common cause of misfires. I am beinging to believe there are abnormally sensitive primers as a shooting bud of mine, a Security Guard at a Federal Facility, during training with M4's and Federal Gold Medal match, he claims that a military M4 went off out of battery. I cannot see any cause other than a primer so sensitive that a little shock set it off. However, back to roller bolts, that mechanism positively keeps the firing pin back until the bolt is in battery. The firing pin mainspring is extremely stiff and that will prevent the firing pin bounce.

[Slamfire]

The Garand mechanism relies primarily on primer insensitivity to prevent an in battery or out of battery slamfire. If you don't know, mechanisms which use the basic Garand mechanism are of course, the Garand, the M14, the M1 carbine, and the Ruger Mini 14. Notice in the following photographs that the Garand type mechanism, which the M1 carbine uses, does not have a positive mechanical means of holding the firing pin back, instead the firing pin is entirely free floating through out most of its travel. There is contact with the firing pin retraction cam, but this is not positive nor does it completely retract the firing pin. This cam is there to break the firing pin out of the primer indent, if this did not happen the firing pin would likely break as the bolt rotates out of battery.



Bolt fully retracted




Firing pin just at retraction cam.





Firing Pin fully forward.

Bolt movement is not perfectly smooth. Slow motion pictures on the M14 mechanism reveal a lot of hesitations, vibrations, going on during bolt closure. Bolt bounce exists on other mechanisms, probably exists with this mechanism. Since there is virtually nothing preventing the firing pin from touching the primer during feed, and during the period when the lugs are not in engagement, there is nothing preventing incidental firing pin impact with the primer. Therefore, in these mechanisms, it is prudent to use the least sensitive primers you can find.

The M1 carbine primer is a very insensitive primer. This was because the M1 Carbine was the first of its kind and the primers could be made very insensitive as there were no other mechanisms using the same cartridge. Making the primer insensitive for the Garand would have likely caused misfires in other mechanisms which used the 30-06 cartridge. The simplest solution was to reduce the kinetic impact energy of the Garand firing pin by reducing its weight. This was not necessary for the M1 carbine, so the Army kept the relatively simple to make but heavy, round firing pin and specified a very insensitive primer .

A history lesson of a sort, the early M1 Garand had a round firing pin exactly like the M1 carbine firing pin. These are pictures of the rare early round firing pins, when Orion 7 had them, they sold out their inventory at $100.00 apiece!







Obviously the Army experienced slamfires in early Garands because the later firing pin was scalloped to reduce weight. On top is the Garand firing pin, the middle the M14, and the bottom a M1 Carbine firing pin.

[T. O'Heir]

It'd be a Norinco M-305. Poly-Tech's are called M-14S' or some such.
The Garand mechanism relies primarily on properly loaded ammo. Slam fires have nothing to do with the rifle's design.
CCI doesn't maker military primers. Their so called 'milspec' primers are nothing but magnum primers. Magnum primers DO NOT have a different cup than any other primer.