Uh, the reason people put 14 oz. of weight into the 391 is to make it weigh about the same as an 1100.
If you want a heavier butt end, add a Gra-Coil or somesuch. Then you REALLY won't have any recoil.
When you're all done with your project, though, you'll go back to the Citori and experiment with alternate loads and a better recoil pad. Why not do that FIRST instead, and save yourself a grand or more?
Last night, I had a borrowed Superposed. I wanted to see where it hit, so I proceeded to powder the first two clays I shot at, then, without further practice, I won a chip shoot with it, against better shooters. This is a gun I had never shot before, ever. It is also the gun that your Citori is based on (your Citori is essentially the Japanese version of the same gun). It is a FAR superior gun for shooting Sporting Clays than my 1100, or a 391, no matter how many silly weights you hang on it. For quail hunting, I'll keep the lighter and quicker 1100, but for clays, that Citori is top-notch.
The recoil got to me after a while, mainly because Browning's standard pad sucks. A Limbsaver would solve that, if I owned the gun. And I was shooting 1 1/8 oz. 3 Dram loads. My regular 1 oz. target loads would drop the recoil further.
I'm not trying to mouth off; I'm trying to save you a grand.