That seems a bit much - consider that Ammo not only lets you advance your combo, but adds extra potency on top. Moreover, it seems like a bad solution, because you're trying counter bad RNG with...more RNG!

If anything, I'd say turn it into guided RNG - if you deviate too much in either direction from the intended/expected outcome, the chance gets dynamically adjusted. In short, the more often RNG works against you, the better your chances get and the more often RNG works in your favor, the worse your chances get. Slug shot proccs? 5% less chance for it to procc next time. Slug shot does not procc? 5% more chance for it to procc next time. That's the basic idea.

That would flatten the performance to a more even level over time without getting rid of the RNG entirely.

But, I'm not a MCH player thanks to barrel, so...yeah.