Slam fire m305 m14s?

Grizzlypeg

Grizzlypeg

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Had a little time on my hands so I thought I would try an experiment.

** Always follow the advice to never chamber a round from anywhere other than the magazine on an M305, M14s, M1A, etc. **

I took some sized 308 brass, loaded it up with soft Federal primers, no propellant, no projectile. Ear muffs and eye protection on.

First, I placed the primed brass in the magazine of my m14s, pulled back the bolt as far as it would go, and let it go. I then drew the charging handle back and inspected the primer on the brass. Not so much as a trace of a firing pin indent.

Now, for the cardinal sin. I first placed said piece of primed brass into the chamber fully. Magazine out so as not to contact the bolt catch. Then I drew back the charging handle as far as it would go it let er rip. No bang. Extracted the cartridge and inspected the primer. Once again, not even a trace of an impact with the firing pin.

The gun fires just fine when I want it to. The bolt and firing pin are clean, as is the chamber. So these are ideal conditions. But, I was expecting a bang.

I tried this with the same piece of brass 15 times in a row, no bang.

By the 10th time, there was a small mark, a pin prick of a mark forming in the center of the primer.

I will repeat this experiment with a purposely high seated primer and report back.

Part 2 High primer

Repeated the experiment, dropping the bolt on a sized case placed in the chamber, using a Federal primer, seated only half way into the primer pocket.

First drop, no bang. Primer exhibits slight mark, similar to attempt #10 above.

Nine more tries, no bang. Primer fully seated by the process of dropping the bolt onto it.

Seems to me its not easy to recreate a slam fire, even with soft Federal primers. There is no where near the striking force on the primer by the inertia of the firing pin alone to detonate it. It would likely require a frozen firing pin. But, given the design of the safety bridge, I am not sure how a firing pin frozen in the forward position can make it past the safety bridge.

By the way, this rifle has headspacing of .002 over saami. Much tighter than a typical Norinco M305.
 
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why would you want to do this experiment in the first place.
I mean no offense, and not trying to be a ####, and I know I swore off giving any m14 advice.... but in this case.....
It is widely accepted that putting a round in the chamber of an m14 type rifle and letting the bolt fly home is one of the few absolute do not do's.
purposefully trying to create a slam fire makes no sense to me unless you are trying to disprove a safety design of this rifle and a practice that every known M14 expert has written about not doing for risk of grievous personal injury.
 
Always follow the advice to never chamber a round from anywhere other than the magazine on your M14, M305, M1A, etc.

My curiosity is to determine what exactly is going wrong when something goes wrong.

What's wrong with a little experiment under safe conditions? I am curious as to how likely this event is to occur, and what conditions it occurs under. Seems to me good area for experimentation and gathering of data. So far, I can't create a slam fire. I am curious as to how it occurs. Is it the inertia of a firing pin? Or is it something else. Seems to me that its something else, like a frozen firing pin, incorrect alignment of firing pin to safety bridge, who knows, because its sure not happening under the conditions I am trying, not even a half seated primer will do it.

I am not advocating anyone do this with live ammunition. I am simply gathering information to set the record straight, and it seems like the inertia of the firing pin alone does squat.
 
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The receiver wall blocks the tail of the firing pin of forward momentum and the firing pin is not free to move forward until the lugs are rotated into the locked position.
 
interesting

I guess slam fire is not something that happens in 'ideal' conditions. Say your bolt was covered in old thickened grease at -20C, or dented or stuck for some reason it might be more likely.

I don't see why you wouldn't try, listening to some people its like you would ABSOLUTELY get a slam fire if you dropped the bold on a chambered cartrige, no matter what, it is a known truth because US army said not to in the 70s. We are not soldiers and dicking around with a cool rifle is about the only reasonable explanation for owning an m305. Besides it seems to me you are perfectly safe in doing so.

As for the half-seated primer, I would think that what would cause an out of battery discharge would be the edge of the bolt face hitting the primer as the cartrige is sitting in the magazine. That is one that particularly scares me reloading for the M305.
 
Before it became a commonly repeated thing on these forums in my earlier days of owning firearms, my standard practice for years was to stick a round in the chamber, drop the bolt full force (to make sure it was in battery) and then put the 5 round mag on.
I always had the rifle pointed straight downrange out of basic practice.
I never once had a slam fire. I'm not advocating it. Just being honest and sharing personal experience on it. I only ever used surplus 7.62 ie norinco etc and I shot A LOT. Hundreds of rounds every trip out sometimes and this was my standard m305 reload method. For some reason I loved having the 6 rounds (pre aia 10 rounders! Lol)

Take it for what it's worth.
 
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Apple tree said:
interesting

I guess slam fire is not something that happens in 'ideal' conditions. Say your bolt was covered in old thickened grease at -20C, or dented or stuck for some reason it might be more likely.

I don't see why you wouldn't try, listening to some people its like you would ABSOLUTELY get a slam fire if you dropped the bold on a chambered cartrige, no matter what, it is a known truth because US army said not to in the 70s. We are not soldiers and dicking around with a cool rifle is about the only reasonable explanation for owning an m305. Besides it seems to me you are perfectly safe in doing so.

As for the half-seated primer, I would think that what would cause an out of battery discharge would be the edge of the bolt face hitting the primer as the cartrige is sitting in the magazine. That is one that particularly scares me reloading for the M305.
Click to expand...

not just repeated by the us army in the 70's …. but a general rule for shooting teams competing with these firearms in the US.
Every M14 rifle book and manual that discusses safe operation of these rifles states to not drop the bolt on a live round in the chamber.

Don't shoot the messenger, I only posted it to possibly save people grievous injury

but you folks go ahead and do whatever floats your boat LOL
 
I am going to continue the testing, and try some different variables. I would like to try it with unsized brass that won't chamber fully, a piece with the neck overly long, also with some soft debris in the chamber to alter cartridge spacing, and with some sort of gummy material (silicone grease?) that would impair movement of the firing pin. I can't however see how a firing pin can remain forward and make it past the safety bridge.

My AR puts far more of a dent in the primer of an unfired round than my m14.

I'd like to see what sort of condition can produce this phenomena. I wish I had a worn out firing pin that I could alter the tail so it doesn't engage the safety bridge, but I'm not willing to sacrifice a good one.
 
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Depends what primer you are using, i know for a fact that it can happen with federal primers. I've had it slam fire with the technique you tested before. Mind you this was before i knew about the dos and do nots of the m14 platform.
 
Percussion said:
Depends what primer you are using, i know for a fact that it can happen with federal primers. I've had it slam fire with the technique you tested before. Mind you this was before i knew about the dos and do nots of the m14 platform.
Click to expand...

Was this with factory ammo, or reloads?
 
I will try to find the source and quote it but there is a method to single load without using the magazine. It is NOT recommended except in extreme circumstances, i.e. life or death.

Insert a round fully into the chamber, and then ride the charging handle forward about half way before releasing. The bolt and spring energy was designed to have enough force to strip a round from the mag and chamber it, releasing from half way effectively reduces the energy transmitted.

Care must also be taken to rotate the rifle so as to direct any possible out of battery detonation out to the side and not up toward your face.
 
no no..... do it, fill yer boots kids!

just so I can point and laugh myself off my chair when one of you blows up your rifle. It will be that sick kind of funny, like 'science of stupid' kind of funny and I hope the injuries are relatively minor.
please post detailed pics if your hands are still able to use a camera :evil:

this place never ceases to amaze me I'll say that.
 
I have no intention of trying this with live ammo.

I am simply curious as to what is the cause. There are many reports of out of battery discharges, that is M1A's, M1's and M14's having a cartridge go off as the bolt carries the cartridge towards the chamber, despite being loaded by the magazine or clip, which is not the same thing as a slam fire in the chamber. Perhaps the two have a common cause?

I can't believe knowledgeable people, after half a century or more, still have no clue as to the actual cause, and simply have a list of things to try to prevent it.

I think a high speed camera filming the interaction of the firing pin hook with the safety bridge might provide some insight. For instance, if the pin is forward as it reaches the bridge, the bridge will catch it and pull it rearward. But what if the firing pin is rearward as one would expect in a situation where the bolt is accelerating forwards? The pin will clear the bridge, and have some distance it can slam forward when the bolt stops. Is the velocity of the firing pin any different between these two situations? What's happening in my case where after 10 tries there is barely a mark on the primer? Is my pin forward when it reaches the bridge or fully to the rear? Would this make any difference?
 
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I got a slam fire in my norinco m-14. I found some pulled .308 tracer bullets at a local gun shop, so loaded some rounds up. I could see the tracer fire up through a scope. I decided to see standing behind the rifle so I loaded a round into the chamber and let the bolt fly home, it went bang. The rear of the brass let go and a piece put a deep gouge in my scope mount and the extractor and spring popped out and was lying on the bench, otherwise no other damage.
 
I'll also make clear no matter how many times I did it before aND did/did not get lucky, I don't advocate it nor do I load in this method anymore. If I do chamber load a round I release the bolt under control and then bump the charging handle forward sharply to ensure its chambered and in battery.
 
Having actually seen a few M14's that self-disassembled after a K-B, I'd implore nobody do this with a live round - not even a fully charged blank. It's a bad ideal all around, as a worn firing pin or slightly out of spec timing on the safety bridge can cause the round to go off without full lug engagement. The results are predictable.
 
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