Could be the smaller powder space underneath the 148's is giving you better ignition consistency. Try a magnum primer with the 125's and see if that improves the grouping any? Also, 125's are short, so they can tilt more on their way and into the forcing cone. Jacketed bullets can usually straighten themselves out doing this, but lead tends to swage into the bore at its angle of entry, and if that angle is much, it will unbalance the bullet, moving its center of gravity off the bore centerline and opening groups up.
The 130's grouping a little above the 125's is normal. Handgun groups rise with bullet weight because, for a given average pressure during firing, they take longer to clear the muzzle, letting recoil lift it a little more before they leave. Bullet weight normally has much more effect on vertical point of impact (POI) in handguns than changes in powder charge do, but raising the charge will also elevate POI a little. This is because, while an increase in charge increases the recoil elevating the muzzle, the barrel time is getting shorter. It just doesn't get proportionally shorter. It's shorter in rough proportion to the square root of the difference in force. It would be exact, but increasing charge also increases total ejecta mass, so the increase is a little bit more than the square root of pressure change.
There are tuning steps that can improve revolver handling of the shorter bullets. Some like a 5° forcing cone angle instead of 11°. Getting all the chamber diameters uniform can help. Getting the alignment of the chambers with the bore perfect by shimming the bolt position can help. If your wadcutters were hollow base, you may have a bore constriction where it screws into the frame that the hollow base skirt is blowing out to compensate for after the bullet goes through it, in which case the constriction needs to be lapped out.
