[Belt Fed]

I recently took off the 556 classic hooded front sight and replaced it with a 550 hooded sight so I could properly shoot with my Swiss diopters.

I placed the hex adjustment screw through the sight, and then the disc that has the roll pin back on. Every thing went back together fine, but i did something wrong when reassembling it.

The adjustment screw is loose. I can maybe turn it 1/4 of the way and it will snug up again, but after firing it gets loose again. As you can guess this was causing hell with with my accuracy.

What did i do wrong when reassembling it? Its supposed to be tight and not move obviously, i just cant narrow down what i did wrong. Im thinking it has something to do with the disc that has the roll pin going through it, maybe i didn't tighten that down enough.

Im pretty confused about the whole thing.

 

[Ben]

I think it depends on how your 550 front sight went into the dovetail.

When you installed the sight, did you have to bang it in there, or did it go in easily?

If it went in easily, sounds like you'll need to remove the roll pin and tighten the disc and hex screw until both are snug against the gas block, then re-insert the pin.
The friction caused from binding the disc and hex screw is what keeps the screw/disc assembly from turning.
But! The screw and disc shouldn't be too tight!
If mounted properly, the front sight should be windage adjustable by turning the hex screw, yet should be snug enough that the screw doesn't turn on its own after firing the rifle.
Having a loose sight and a loose screw will most likely cause your scenario.

On the other hand, if you had to really bang the sight in, it won't matter if your hex screw is loose because the sight is most likely seated in due to a tight fit. Also, your sight probably won't budge when you turn the screw.

 

[Belt Fed]

I think thats what it was.

I had to bang the thing in, and then place in the hex screw. The hex screw was the only thing i snugged up to the gas block, i didnt snug up the disc with the roll pin on the other side of the block. As a matter of fact it explains why i bent the roll pin when i reassembled things the first time around.

Everything seems fine right now. One last question though, when adjusting the hex screw, how hard should it be to rotate the screw clockwise and counter clockwise?

When rotating it clockwise, its a little harder to adjust. Counter clockwise isnt as hard. It seems like this should be normal. Is this correct?