question about AR15 slam fire?

[mconley]

Hey I have a bushmaster xm, I noticed the other day that everytime I chambered a round then extracted it, it had a indention on the primer from the fireing pin. I called bushmaster ( which should be called Dickmaster ) due to customer service, but thats anouther thread all in its self. Anyway they stated it was normal, I have never noticed it on any other of my ARs I have owned, but then again I was never looking for it either. Is it normal? Is a slam fire possible with this?

Also is there any good ( free ) resorces for tactical shooting or just shooting/operating in general for the AR?

 

[USPc40]

According to posts I've read on AR15.com, this is normal.

 

[mconley]

Man It just looks like a bad thing. Scared the poop out of me

 

[phylodog]

It's normal. The firing pin is free floating and will make contact with a primer whenever you chamber a round. I've never seen it cause a problem but it is also the reason our Officers are required to carry their rifles with an empty chamber. The forces generated during a crash could cause an unintentional discharge.

 

[mconley]

ok then ... does anyone know free refrences on shoot techniques?

 

[Fenway]

This belongs in Long Guns. Not General

 

[mconley]

sorry

 

[SavageEagle]

I will say that this is a problem with Free Float pin in the SKS and AK. What causes a slamfire, from what i've researched, is the firing pin block gets gunked up from dirty ammo and lack of cleaning. At some point in time the gunk piles up and the pin sticks out causing a slamfire.

it had a indention on the primer from the fireing pin

I freaked out too when I seen this on my SKS and started looking it up. According to everything I read, this is possible on any semi-auto firearm with a free floating firing pin. I plan on upgrading my bolt/firing pin block when I get a chance. I'm currently building an AR and hadn't taken this in consideration so thanks for bringing it up!

 

[sloughfoot]

Rifles with free floating firing pins all do this. It is why hard military type primers are highly recommended when reloading for M1, M1A, AR15, Mini 14 and others.

It is also why the AR10 type has a spring on the firing pin to keep it away from the primer. The SKS can also be equipped with a spring to accomplish the same thing.

 

[cosermann]

Keep the firing pin channel clean. If one is really paranoid one can switch to a lower mass firing pin (although these have their own drawbacks). IMO, the current design standard chrome firing pin is best.

Always keep the muzzle pointed in a safe direction - especially when chambering a round.

 

[mconley]

THANKS ALL!

 

[agentl074]

Rifles with free floating firing pins all do this. It is why hard military type primers are highly recommended when reloading for M1, M1A, AR15, Mini 14 and others.

It is also why the AR10 type has a spring on the firing pin to keep it away from the primer. The SKS can also be equipped with a spring to accomplish the same thing.

So thats why theres a spring on my pin. Thanks - so its like another safety feature of the AR-10A2?

 

[CMB69]

...Is a slam fire possible with this?

The only unintended discharge I have experienced was an M-16 slamfire. Scared me and could have had very bad consequences.

Now when I load my AR I ALWAYS make sure that the backstop will contain the bullet should it happen.

I shoot Highpower matches so there have been plenty of opportunities for it to occur. It has not happened to to me again but have seen it happen to others a couple of times. It is not common, but it can, and occasionally does, occur.

 

[rhino]

Now when I load my AR I ALWAYS make sure that the backstop will contain the bullet should it happen.

This should be done for all guns, always, by everyone.

 

[Old Syko]

I agree with all the above but will add just one simple bit of advice concerning handloading for an AR. Winchester primers are possibly the softest on the market and certainly not my choice for AR use. The earlier refference to "military primers" is a good one although CCI 400s and 450s have served me well for many thousands of rounds. Same manufacturer.

 

[mrw]

I heard Federal's were the softest.

I added a firing pin spring to my SKS. Do they make such a creature for an AR?

 

[sloughfoot]

I heard Federal's were the softest.

I added a firing pin spring to my SKS. Do they make such a creature for an AR?

You are right about the Federal primer being the softest. Winchester and CCI Military are hard primers. About 90% of my 223 reloads are with Remington 7 1/2 primers- 4000+ per year for competition. Never had a slam fire, never seen one, but then, I am just one guy...

Winchester are definitely hotter than Remington but that has nothing to do with hardness of the primer.

The firing pin spring mod for the SKS is usefull but I don't know of the same mod for the ar15. IMO it is not necessary for the AR15.

 

[Old Syko]

Although a bit dated, just a quick link to support my statement concerning WW primers. I will post others later concerning the actual hardness of the material rather than the thickness used but you can get an idea from this link of why I've stated what I have.

BTW the only slamfires I've heard of were caused by either primers not being seated deep enough on reloaded ammo or broken firearms, usually the fireing pin being broken and jammed forward in the bolt. Had this happen with a mil-spec 45 on the first round of an 8 round mag some years ago. Talk about a suprise!

http://http://www.jamescalhoon.com/primers_and_pressure.php

 

[possum_128]

I was the one in the shop the day you called Bushmaster. How did it work after you cleaned the firing pin?

 

[jeremy]

It's normal. The firing pin is free floating and will make contact with a primer whenever you chamber a round. I've never seen it cause a problem but it is also the reason our Officers are required to carry their rifles with an empty chamber. The forces generated during a crash could cause an unintentional discharge.

Throw the BS Flag high in the air. Carried one loaded for years in CZ's Crashed many vehicles, was even in 'crashhawk landing hard. Never had a pop.