When I'm doing load development for either rifle or handgun I do everything possible to remove the vagaries of my own performance from the equation. That means shooting from a bench, off heavy bags.

Rifle development always starts at 100 yards. Handgun calibers start at 50 yards. Depending upon caliber and intent, both may end up being tested at greater distances once I'm further down the rabbit hole.

I don't find developing for handguns any less straightforward than for rifles. For me, working at distance and from a bench are the keys.

Most of the pistol shooting I do is freehand. Much as I enjoy that - among other things, handguns are almost universally used that way in the real world - no way would that work for me for load development!