My FN-49 Blew Up!

Well, Slamfire, I guess I have to bow to expertise as you have had and seen more slamfires than anyone else I have ever known.* But in my much more limited experience, a slamfire with no backup to the firing pin (that is nothing but firing pin inertia) will let the primer internal pressure push the primer metal back out, even into the firing pin hole if the design allows it. It takes a goodly amount of firing pin inertia and case support to get that kind of primer appearance.

The high primer type slamfire is the result of the bolt face hitting the primer; there usually is no firing pin mark at all since the firing pin didn't set off the primer, the bolt face did.

The FN-49 and FAL both have very strong firing pin springs just to prevent firing pin creep and possible slam fires, since the bolt is moving straight forward and no inertia is taken up by the bolt turning.

I still think there is something about that KB we don't know.

*Nine times out of ten when someone says "slamfire" they mean the bolt was locked but the sear jarred off or a light trigger was pulled accidentally, but that certainly is not the situation when a receiver blows apart.

Jim
 
Bear in mind we're just guessing here having not had the actual rifle in our hands. Also bear in mind no-one is "having a go" at you, we're just curious to find a definite answer to what & how this happened.

2 things that come to light from your post.
Firstly that is an abnormally high incidence of incidents.
Secondly there was a change made (the spring).

Based on that I'd guess there is a problem somewhere within the rifle/ammunition/user chain. I don't think it is drastic, but it IS causing incidents so it probably needs fixing for your comfort & safety. Ammo with 10 FPS is very, very minor, but ammo with a different pressure curve from a different propellant may well be causing the gas to behave differently, even if the velocities are identical.
 
Bear in mind we're just guessing here having not had the actual rifle in our hands. Also bear in mind no-one is "having a go" at you, we're just curious to find a definite answer to what & how this happened.
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Oh, I never really thought anyone was "having a go" at me, I know you're all trying to help.

2 things that come to light from your post.
Firstly that is an abnormally high incidence of incidents.
Secondly there was a change made (the spring).
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I'm not overly inclined to think that the spring is the issue as this is the first incident I've had since replacing it. I actually had more slamfires before with the OE spring and I intentionally put in a much heavier spring because of it. Also, I'd shot the rifle a fair amount with Federal ammo after replacing the spring without issue.

Based on that I'd guess there is a problem somewhere within the rifle/ammunition/user chain. I don't think it is drastic, but it IS causing incidents so it probably needs fixing for your comfort & safety. Ammo with 10 FPS is very, very minor, but ammo with a different pressure curve from a different propellant may well be causing the gas to behave differently, even if the velocities are identical.
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The more I think about it, I think the problem probably has to do with the ammo, gas system adjustment, or both. As I stated earlier, I did have the rifle checked by a gunsmith who seemed fairly familiar with FN-49's and he told me it was mechanically fine. An improper setting on the gas system or defective ammunition, however, wouldn't be something that he would have been able to tell unless he fired the rifle. I'm beginning to think that one needs to adjust the gas system for a specific loading and either stick just to that or readjust the gas system anytime a different ammo is used.

Either way, I'm getting rid of this rifle. Even if it is mechanically fine, I have no use for a gun that I have to be so picky about ammunition with. I feel that I can sell it in good concience since a gunsmith has given it the mechanical OK. I've also opened the gas vent all the way (this allows the least amount of gas to act against the piston) and set the plug to the grenade launching setting (this prevents semi-auto fire) so that whoever I sell it to will have to adjust the gas system for whatever ammo he decides to use.
 
You had more slamfires before? What happened those times and how often have you rebuilt that rifle? There has to be something wrong somewhere.

That is a bit like someone saying he is getting tired of being struck by lightning!

Jim
 
I sure hope you plan on telling the next owner about your experience with this rifle.

And, one gunsmith, who may or may not have been familiar with the rifle, wouldn't ease my conscience if the next owner got hurt because the problem re-occurred.

I know its a bite in the butt, but, I don't think my conscience could rest very easily after I sold the rifle for anything other than a wall hanger, making dang sure it was disabled from every firing another round again.

And, frankly, I am surprised the Gander Mt. Gunsmith gave you a go ahead to re use the rifle, did you get it in writing? Cause if somebody gets sued, you better have either a no fire letter signed by the buyer, or paperwork covering your butt.

I myself, would torch the dang thing, eat the lost money, and sleep better at night.
 
Originally posted by Jim Keenan
You had more slamfires before? What happened those times and how often have you rebuilt that rifle? There has to be something wrong somewhere.
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When I had issues before, the rifle would fire multiple shots with one pull of the trigger. Replacing the one-piece firing pin with the later two-piece type and replacing the firing pin return spring seemed to fix the problem as I've had no more issues until now (it's been running just fine for a couple of years now), but this is the first time I'd shot Winchester ammo since replacing the parts. Since replacing the firing pin and spring, I've shot Federal and various milsurp ammo without issue. All this info along with the mangled case was provided to the gunsmith that examined the rifle.

Originally posted by frick74
I sure hope you plan on telling the next owner about your experience with this rifle.
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I do.

And, one gunsmith, who may or may not have been familiar with the rifle, wouldn't ease my conscience if the next owner got hurt because the problem re-occurred.
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So how many gunsmiths should I take it to before I sell it? There aren't that many around my area.

And, frankly, I am surprised the Gander Mt. Gunsmith gave you a go ahead to re use the rifle, did you get it in writing? Cause if somebody gets sued, you better have either a no fire letter signed by the buyer, or paperwork covering your butt.
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No, but that's probably because he didn't feel it necessary to charge me anything. Also, if something does happen with the rifle later on, I doubt it will come back on me because I only sell through FFL's (I've had bad experiences with private party sales before).

I myself, would torch the dang thing, eat the lost money, and sleep better at night.
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That is not going to happen. I'm simply not willing to take a complete loss on a $900 rifle particularly when I've been told by a professional gunsmith that it's not unsafe. If I find out that there is indeed something unsafe about the gun, I'll certainly have it fixed before I sell it, but I've simply got too much money wrapped up in this thing to turn it into a wall-hanger or doorstop.
 
Update

On a hunch, I tried a little experiment. I deprimed a spent shell casing and re-primed it with a Winchester large pistol primer. I then loaded the case into the magazine and let the bolt fly. While the primer wasn't set off, I did notice a slight dimple in it from the firing pin. What do you guys think? Could my firing pin be too long? I'm thinking perhaps a firing pin that's a bit too long coupled with a high primer may be the culprit. Any thoughts?
 
Dimpled (but not fired) primers are normal for the FN semi-autos.

Runaway firing, out of battery discharges, that rifle has a serious (& possibly illegal as in it could be decreed a machine gun), problems. I can't believe that we were & are being given only parts of the story. Without all the information we're completely wasting our time while you cherry pick symptoms.

You need to either get a professional gunsmith who knows the FN rifles fix it or break it down before you get sued or arrested or someone gets shot with it. I know all the talk about the RIGHT to own firearms, but why do so many refuse to accept the RESPONSIBILITY that comes with that right?
 
Dimpled (but not fired) primers are normal for the FN semi-autos.

Runaway firing, out of battery discharges, that rifle has a serious (& possibly illegal as in it could be decreed a machine gun), problems. I can't believe that we were & are being given only parts of the story. Without all the information we're completely wasting our time while you cherry pick symptoms.

You need to either get a professional gunsmith who knows the FN rifles fix it or break it down before you get sued or arrested or someone gets shot with it. I know all the talk about the RIGHT to own firearms, but why do so many refuse to accept the RESPONSIBILITY that comes with that right?
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I agree.

If you have a mechanical problem, and doubling often sounds like a mechanical problem not a primer problem, then you are the lucky owner of an unregistered machine gun.

Your prize is five to ten years in the pokey. Maybe your cell mate will make you wear a French Maid’s outfit. :eek:

The BATF has gone after and put people in jail whose semi automatic rifles doubled due to worn or out of tolerance parts. They have this idea that if your gun shoots two or more rounds with one trigger pull, than it is a machine gun.

Therefore you have a machine gun.

Knock, knock, BATF calling.........:(
 
"Also, if something does happen with the rifle later on, I doubt it will come back on me because I only sell through FFL's (I've had bad experiences with private party sales before)."a

Bad mojo, plain and simple.

I am an FFL and the idea that you would dump a problematic firearm with me, or any other dealer is rude, immoral and or possible fraud.

So you expect your dealers insurance to absorb the lawsuit that results from you dumping an unsafe firearm on HIM?

Frankly, if you WERE honest with me, you wouldn't be offered full price for a defective firearm, only because you have that much money in it.

Good luck with your rifle, I seriously hope someone doesn't lose an eye, or worse, because of your need to recoup your investment.

And thats the best I can say, without getting booted for what I really want to type.
 
Originally posted by wogpotter
Dimpled (but not fired) primers are normal for the FN semi-autos.
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OK, thank you. That's the kind of information I was looking for.

Runaway firing, out of battery discharges, that rifle has a serious (& possibly illegal as in it could be decreed a machine gun), problems. I can't believe that we were & are being given only parts of the story. Without all the information we're completely wasting our time while you cherry pick symptoms.
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I've given you all the information that I have (some of it multiple times). If there is more to the story, then it comes from before I owned the rifle.

You need to either get a professional gunsmith who knows the FN rifles fix it or break it down before you get sued or arrested or someone gets shot with it. I know all the talk about the RIGHT to own firearms, but why do so many refuse to accept the RESPONSIBILITY that comes with that right?
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Is there any gunsmith in particular that you suggest? I did take the rifle to a professional gunsmith who seemed, as far as I could tell, to be familiar with the design within 24 hours of the incident and he gave me the OK. My whole point in posting this was to try to ensure that I don't sell an unsafe rifle, how is that irresponsible?

Originally posted by Slamfire
If you have a mechanical problem, and doubling often sounds like a mechanical problem not a primer problem, then you are the lucky owner of an unregistered machine gun.
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I have heard of one case of an over-zealous ATF agent trying to portray a malfunctioning rifle as a machine gun (a FAL if memory serves) but the attempt didn't fly.

Your prize is five to ten years in the pokey. Maybe your cell mate will make you wear a French Maid’s outfit.
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Gee, that's helpful:rolleyes:

Originally posted by frick74
"Also, if something does happen with the rifle later on, I doubt it will come back on me because I only sell through FFL's (I've had bad experiences with private party sales before)."a

Bad mojo, plain and simple.

I am an FFL and the idea that you would dump a problematic firearm with me, or any other dealer is rude, immoral and or possible fraud.
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When did I ever say that I planned on selling the rifle to anyone, FFL or otherwise, without disclosing the situation? I have no plans to "dump" a problematic firearm on anyone without telling them why I'm selling it and to suggest that I'd be so dishonest is rather offensive.

So you expect your dealers insurance to absorb the lawsuit that results from you dumping an unsafe firearm on HIM?
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Well, if HE decides to buy the gun after I've told HIM about the issues, then yes, I feel that it's HIS problem at that point.

Frankly, if you WERE honest with me, you wouldn't be offered full price for a defective firearm, only because you have that much money in it.
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I don't expect to get full price for it nor did I ever say that I did. However, I'm not willing to just torch and throw away something that cost so much and say "oh well".

Good luck with your rifle, I seriously hope someone doesn't lose an eye, or worse, because of your need to recoup your investment.

And thats the best I can say, without getting booted for what I really want to type.
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Have a nice day.:rolleyes:

You know, I'm really beginning to regret posting this. I am trying to do what I view as the responsible thing by taking every precaution not to sell someone an unsafe firearm (even though a gunsmith already told me the rifle was OK) and I'm getting attacked for it. No good deed goes unpunished I guess.
 
Slamfire, that's not really apples-to-apples. Olofson intentionally installed full-auto M16 parts in his AR with the specific purpose of making it full-auto. He then tried to claim the rather weak defense that because the gun couldn't go through a whole magazine without jamming, it was not a machinegun.

My rifle, on the other hand, has no full-auto parts intsalled nor did I intentionally modify it to fire full-auto (quite the opposite actually).

A more analagous situation to mine would be that of John Glover against whom the the charges by the over-zealous ATF agent were dropped.

http://www.freerepublic.com/focus/f-news/1467481/posts
 
Is there any gunsmith in particular that you suggest?
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Here is the contact info for a hugely experienced & widely respected smith with a great deal of experience with the FN semi-auto rifles.
I'm taking you at your word & hoping this will solve the issues with this rifle and make it safe & you happy.
I suggest you contact them directly with a full description of the issues holding nothing back & see if he can fix you up.
http://www.arizonaresponsesystems.com/
 
Quote:
Is there any gunsmith in particular that you suggest?

Here is the contact info for a hugely experienced & widely respected smith with a great deal of experience with the FN semi-auto rifles.
I'm taking you at your word & hoping this will solve the issues with this rifle and make it safe & you happy.
I suggest you contact them directly with a full description of the issues holding nothing back & see if he can fix you up.
http://www.arizonaresponsesystems.com/
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Thank you, I'll look into that.
 
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