Base for a FF III to fit Franchi Affinity 20

[strutnva]

Thinking about putting a FF III on my Franchi Affinty 20 ga.  What base do I need to mount the FF as low as possible?  Thanks for any input.

[turkey_slayer]

Burris 336 mount. Burris part # 410333. Need two holes tapped. 8-40 thread half inch apart. Buddy just got his back yesterday. I got it here if you want a pic