FSP Gas Leak (Pinned)?

[OldState]

A few weeks ago I installed a DD Omega X FSP which required removal of the FSP. Today I attended a class and it was the first time I really got to try it out.

About midway thru the class (250 rounds) I noticed a black spot on top of my thumb joint (where it joins my hand). I was gripping the rail with my hand under the FSP and my thumb parallel to the barrel. It looks as if gas was leaking and "staining" my hand. It wasn't a lot because I couldn't feel it at all (no gloves worn) and it wasn't a real dark mark. More like a smudge.

Is this normal for a FSP to "leak" a little gas or could I have done something wrong putting the FSP back on? The pins are in as far as they were from Colt and the pin for the gas tube is in correctly. I never was able to grip in the area on the FSP before.

The gun functions fine and ran both LC XM193 and Brown Bear.

[nimdabew]

It's normal.

[OldState]

Thanks. That is what I thought I just never shot the rifle with my hand in that position. Some guys at the class had me a tiny bit worried so I thought I'd ask here.

[Detmongo]

i have the same thing with two different uppers, other than carbon on my flash lights or fingers both uppers run fine.

[Blowby]

Think about it, you have a slide fit for the gas tube and the FSP or low profile gas block. Gas will escape until all the small passages clog up with carbon deposit's. It's normal unless it's excessive.

[sinjinhawk]

It's normal the gas will leak out a bid especially if your rifle is new or you have just replaced it. No worry beause after about 300-500 rds the carbon fouling will sealed the gap.

[Eric D.]

The question of gas block leakage has come up a few times. I had the same thing happen on a BCM M4 upper. I never had any short stroking issues and I don't doubt that any leaks will seal eventually but Mr. Davis' writeup got me wondering. Has anyone seen this leakage on Colts or issue weapons?

Also check for leaking, the most common sign is a brownish, rust looking stain around the barrel where it passes through the gas block. Some people will tell you that this is normal and will “seal” with time – it may be normal, but it is not right. The TDP specs for the barrel to gas block fit are one of the most exact measurement on the gun, this is a zero tolerance fit and is not supposed to leak at all – if you are getting leaking here, I strongly suggest talking to the supplier or builder about making it right.

[sinjinhawk]

Mr. davis advice should be taken seriously, if leak does not stopped then you should contact manufacturer to correct the issue. Mine just stop at about 400 or so rds and has no problem.