Yes, it has been worked out. The Benelli will cycle a wide range of loads. But the best solution is to use real buckshot loads instead of the reduced "tactical" loads. Tactical buckshot is a design trade-off, you trade some terminal balistics for a reduction in recoil. In theory this would increase the effectiveness of some shotgun users. Gas opperated shotguns do not have as much recoil as other actions, so the trade-off of a reduced load might not be worth as much.
I am not against "tactical" loads per say, but they are an equipment solution to what is a training problem. I think proper weapon fit and training are better solutions than using less effective ammo.