FN-49 front handguard blowing off

[Symbolic]

I purchased an Egyptian FN-49 in 8mm on here a few months ago and finally got around to cleaning it and shooting in December. Unfortunately, I was only able to shoot two rounds out of it because the upper front handguard kept getting blown off. Does anyone have an idea, or know, why? I inspected both the front and rear upper handguards and both appear to be intact and have the same amount of wood that fits under the lower band which holds them down. I checked a schematics list and I don't think I am missing any parts. I am wondering if it's over gassed, so I am about to research that.

[Symbolic]

Probably should have researched before I posted. Just answered my own question. Sorry for wasting your time

[Oh Shoot]

3 hours ago, Symbolic said:

Probably should have researched before I posted. Just answered my own question. Sorry for wasting your time

Well, now that you have us interested, what is the story?

- OS

[Symbolic]

From reading a few forums last night, I am not the only one with the problem of the front handguard getting blown off. So, last night I closed the gas port completely (or so I think). After work today, I took the FN-49 to the range. First shot and the handguard blew right off again and the rifle cycled the next round. I'm thinking that a part (or parts) might be defective in this rifle, because it doesn't make sense to me that the rifle would still be able to fully cycle with the gas shut off. It's either user error or equipment error. I am going to have to comprehensively check the gas system components of the rifle as well as read an instruction manual because I am at a loss right now. In one forum post, a guy mentioned that he just duct taped the front handguard to the rifle and has had no problems since. While that may not be the best answer, if I don't find out why the rifle is operating like this, I might have to develop a wrap of some kind for this gun... or fork out some cash and take it to a gunsmith.

[Symbolic]

There is a hole in the top of the gas tube for gas to escape directly vertical and therefore I may have be absolutely wrong about the gas function on this rifle. This paragraph is directly from the FN 1949 manual:

"c) Gas regulation. - The size of the slot for the escape of gas and its location are such, that when it is completely open the pressure exerted by the gas on the piston is insufficient to operate the mechanism. That is the point where the regulator intervenes. The regulator is built from a simple threaded sleeve (6), screwed around the gas cylinder. When the sleeve is screwed in, the opening for gas escape decreases and consequently the thrust of the gas on the piston is growinq, a good functioning of the rifle, without undue fatigue for the mechanism, is thus ensured. The gas regulation is carried out by the manufacturer, when the rifle is assembled."
Source: http://www.biggerhammer.net/manuals/pdfs/FN49.pdf

So what I interpret this to mean is that when I closed the gas system, I put more gas pressure on the piston instead of less, which explains why it continued to cycle another round after a shot. However, the dilemma is that if I open the gas port, I will have more pressure on the handguard than on the piston, and the handguard will continue to be blown off the rifle. Am I wrong? I"m not a very smart man...

[Sidecarist]

Look at this video at the 6min mark it shows the front of the handguard and how the gas is supposed to be vented.

 

[Symbolic]

Thanks for posting the video. I viewed it during my little bit of research a couple nights ago. The rifle I received came in the same gas component configuration as the rifle shown in the video at the 6 minute mark. That is obviously a very open gas position and one reason why I thought the handguard was being blown off. Even being in such an open configuration, the rifle was still able to cycle ammo. And there's another video on Youtube where a guy's FN-49 does not cycle ammo in that configuration. I thought completely closing the gas port would eliminate the handguard being blown off but it did not.