Custom red dot sight mount-need input

[Bigdude]

I am currently designing a simple U-shaped mount that will hold my red dot sight (will be similar to picture below-except my mount will have two small vertical tabs at the front and rear of the mount to prevent access to the piston). Reason why is because I need my red dot mounted much lower than any upper rail can provide. My plan was to modify my Bonesteel Arms upper rail by basically cutting out a section of the top and sides. Then I will have the U-shaped mount fabricated and fastened to my modified upper rail. The U-shaped mount will be made of mild steel billet.

First question, how much space would you recommend that I leave between the top of piston and bottom surface of mount?

Second question, what material thickness should I use for the bottom of the mount? I want to use the least amount possible to keep it low, so I was thinking of approximately .075?.

Any information would be appreciated.

[MeatAxe]

Are you wanting to co-witness your red dot with the iron sights? This is difficult to do with the Vz58 iron sights, as low as they are, especially with a straight line butt stock.

I would be concerned with the structural integrity of the top rail if it?s been cut like that and had a steel section added (I assume riveted or screwed to the aluminum top rail). Also, the aluminum and steel pieces will not expand at the same rate when heated while shooting, which could be a problem.

I?ve pondered this problem myself. Since nobody I know sells a taller front sight base for the Vz, if you?re going to fabricate something, it occurs to me that the solution would be to cut the front sight tower in half and then insert / weld a section of steel (say a square nut or two) of appropriate size and  width between the two halfs of the sight tower to get the fsb high enough to co-witness with the red dot, where ever it is mounted on the rifle. If you could raise the front sight tower by 1/4" to 1/2" that would seem to be enough to co-witness most red dot sights.

[Bigdude]

I just dropped of my rifle, red dot and upper rail at the gunsmith. The solution we came up with is to first cut out the section of the upper rail keeping it a hair above the piston. Then weld on a mounting plate that matches the mounting screws (see picture below). Both the upper rail and mounting plate are made of aluminum. With this modification to the upper rail, co-witnessing will be possible.

[MeatAxe]

Interesting...keep us posted on how it works out.