FN Commercial Mauser scope base?

[70worm]

What's the difference between a .860 and a .500? I assume it's a measurement? What do I measure to see which one I got?

 

[mdwest]

Im pretty sure those numbers are referring to the hole spacing on the rear mount.. but would need to see the ad/specs of the scope bases you are looking at to be sure (.860 and .500 are very common hole spacing measurements for rear mounts on LR mausers)...

 

[70worm]

Thank you.