HK416 BUIS issues

[HKPRO]

I am clear on the fact that the rail on a 416 upper is 6mm higher than a DI M4.

I have the folding front sight that attaches to the gas block and I have an old GGG folding rear BUIS that I put on behind the Eotech. When trying to sight in the irons, it shoots about 6 inches high at 25. There is no way to adjust for elevation either front or rear.

Do I just need to get a GGG front and mount that on the rail? Is it an issue to mix or match BUIS to one manufacturer?

Other issues?

Thanks in advance M4pros out there.

[Armati]

If I understand you, you have an HK416 WITHOUT the HK flip up front sight.

You instead have a flip up front sight that was meant to be mounted on a gas block.

I think you will need to get a new front sight that is designed to be mounted on the top rail. The one you have will be too tall and the sights will not properly co-witness.

[HKPRO]

No, I have the HK flip up front sight that mounts on the HK gas block. I am not crazy about it and probably won't keep it. I think I need one that mounts on the top rail that has elevation adjustment.