I am looking into replacing a milled gas block with a block that has rail cuts to add a flip-up front sight(rail on the top only).  Do any of the boardmembers have an ideas or manufactures links or dealers.

I remember seeing a combination gas block and flip-up front sight somewhere, do any of you have any information on this as well.

Is removing the gas block that difficult?
I know there are two pins that go into the block, do you just remove them?

I've got a VERY lightly used one to trade.
email me for some pics if interested.
[email protected]

There are two taper pins securing the gas block. Be sure to punch them out from the small end side. Hopefully your 'new' GB will have the same hole pattern (good luck).

I've placed and replaced several standard GBs and have been fortunate in that the hole pattern matched. YMMV.

GG&G has a really cool gas block with flip up sight.

http://www.gggaz.com/products/TactModFUP.php