I've never tried to develop a soft, light load. It seems to me, a fast powder makes for a fast recoil impulse, that is, a change of momentum over a shorter period of time. The pressure with something like Red Dot, Bullseye etc is going to spike quickly. If you're loading to low peak pressures, you'll get low velocities for the sharpness of recoil. I would try to find a powder that gives good velocity with a slow push rather than a sharp jab. That might be light loads of HP-38, Unique, Universal, or BE-86. If I was loading for this, I'd begin with starting loads of BE-86. In my experience, it's a wonderfully soft powder that's capable of good performance. I would also consider 125-grain bullets. I haven't thought about it enough or tried it to know if those would be better, but it seems logical.