I'm designing what is called a "Red Dot Sight Mount" (see image below) for a handgun.

Disclaimer: this kind of part is not regulated (at least not in any country that I can think of) and does not modify the functioning of the gun in any way (it's just a part that holds an electronical sight on top of the firearm), that's why I'm attempting to build this even if I have no experience in mechanical engineering.

This is what it looks like (this is one from a random manufacturer): Example of Red Dot Sight Mount

My question is: what should be the minimum thickness of the top part (the part with a red line on the picture above) so it doesn't break or bend/deform? The material is 7075 Aluminum with a type 3 anodizing finish.

The main thing to take into account will probably be the recoil of the firearm (9x19mm caliber pistol) which produces a recoil of about 2.7 kg.m/s, but then I have no idea what to do with it.

Most mounts sold commercially are about 0.10in-0.15in thick but I would like to go thinner to have the sight sit lower.

I understand the answer to this question might be complex and it might not be possible to give a numerical answer without (much) more details, but could you perhaps give the method and main formulas? Or a software that could be used to run simulations?

  • $\begingroup$ Make it curved, but 1/10th is already fairly thin for aluminum. $\endgroup$
    – Rob
    Commented Dec 23, 2022 at 0:52

1 Answer 1


No one would design this, they would do it iteratively. Too many variables:

  • acceleration of the slide starting and stopping
  • mass of the sight
  • grade of aluminum
  • mounting method

"Minimum" isn't a spec. A spec is an expcted lifetime on a specific platoform.

I don't know who could actually tell the difference in a .1" vs .05" elevation of a sight other than aesthetically. And it would be easier to mill it deeper into the slide.

  • $\begingroup$ I think that mount is meant to slide into the rear sight dovetail. $\endgroup$
    – Drew
    Commented Dec 18, 2022 at 11:28

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