Just ordered one in AR base myself, that the plan to replace AR base and attach on my 870 SM. It just seemed like a good deal with protecter included. I hope to hav AR soon and thought I could save has for then to slay pigs.
I am leaning towards the 336 base. If I understand correctly, I can remove sight from AR mount and protecter and mount ff3 directly to 336 base. First, I need to have 336 drilled and countersinked for my. 870
Have you converted yours to your shotgun yet Prohunter?