You could always get the 50 mm and try it out for yourself. I had purchased the 50 mm because it was going on my Sako and the lowest Optiloc rings could accommodate for a 52 mm ( = or -) so I went that route. Knowing what I know now I much prefer the 42 mm. Should have listed to stubblejumper in the first place. I just had to try it and see for myself. Good luck in your choice...