Question for AR builders

[ScouT6a]

A friend presented me with a new issue to me today. He has an AR with an A2 front sight. He told me that when he was cleaning it he found powder residue one the left side of the front sight, around the roll pin near the gas tube. This is a factory made DPMS rifle with less than 500 rounds through it.
Is it possible to have a gas leak in this area. I have never seen this in 22 1/2 years in dealing with M16s and M4s or the same amount of time owning ARs but I have seen some strange stuff with these rifles.

 

[KoopaKGB]

Was he shooting on line with other shooters? Is it possible that carbon is from another firearm?

 

[ScouT6a]

No Sir, he was shooting alone.

 

[Mgderf]

Wrap a piece of toilet tissue paper around the suspected area and fire a few rounds.
If there is any leaking underneath,you'll see it.

 

[indyjohn]

Of course it is possible. Can't say how likely though. You should put eyes on it, you'll know what you're looking at where he may not. Fire 50 more rounds through it now that he's cleaned the area. Could be a new FSB in his future.

 

[phylodog]

Not uncommon for a gas block or FSB to leak, my 12.5" BCM does quite a bit, especially when the suppressor is on there. It cycles reliably so it doesn't concern me.

 

[indyjohn]

Not uncommon for a gas block or FSB to leak, my 12.5" BCM does quite a bit, especially when the suppressor is on there. It cycles reliably so it doesn't concern me.

^^^^ Here ^^^^

Beats the heck out of replacing the FSB..

 

[ScouT6a]

He did say it is still cycling fine.

 

[sloughfoot]

It is not uncommon and it hurts nothing.

 

[rvb]

the gas tube isn't exactly press fit into the block. a little gas out around the tube and roll pin isn't uncommon at all.
-rvb