TexasCHLforum.com

A-R wrote:Could be a sight height problem. I believe you need a front sight specifically engineered to sit on a gas block picatinny rail (as opposed to a full length handguard/quad rail set up)

That's true, and that could have been the reason for the warning. If the rail on the gas block doesn't mount the sight at the same height as it would be mounted on a forward rail, then your elevation adjustments will be useless.

Perhaps a simpler solution, although more expensive, would be to ditch the gas block for a low-profile one, and then mount a floating quad rail. Put the front sight on the quad rail. You'll also free up a little more accuracy in your rifle that way.

If you have a A2 standard front sight, you can mount a rear flip up sight and an optic, and the front sight won't bother you one bit.

I submit the carbine I built for my wife as an example:


That rear sight is an A.R.M.S. #40 L-P. The front sight is a standard A2 front mounted on a M4 profile barrel.

All of this said, unless the front sight you bought is plastic, It seems to me that a metal flip up front sight wouldn't be that affected on a rail type gas block. After all, the A2 front sight is mounted on the gas block.