Baikal's rib size?

[PrivateEye87]

What is the rib size of "Baikal O/U IZH-27" and "Baikal Semiauto MP-153" ?
I need to install fiber optic sights on both of them and i couldn't find their rib size any where.

 

[oneounceload]

If you have a caliper or fairly accurate ruler you can measure them. Are these for any particular purpose, like HD or something?

 

[PrivateEye87]

i dont have my guns with me. Yes i need use them for hunting

 

[oneounceload]

For upland birds and clays, I have found that the fiber optic sights tend to distract my eyes from the targets, resulting in a miss. There are several types - some that magnetically stick, some with adhesive, others that have prongs that wrap.