Beretta 390 20 ga site/scope

[wolverines]

I have a rifle site barrel on my 390 20 ga.  I would like to put a ff3 on it but haven't found one that fit.  The gun is centered but shooting about 15" low.  I have no more adjustment left in the sights.  I can compensate but I have young shooters that will use this gun and I want to take out the guess work.  I would put a saddle mount on it if anyone makes it, but I don't want to drill it.