Welcome to 'the next step' of reloading; where you take your sanity in your own hands and stray below (never above) the reloading manual.
As Ganderite says, no need to go all the way to 9 grains - you could likely go as low as 5, but at that point the load is not generating enough heat to burn all the powder, and you end-up with a mess. But you have little to fear going below the 'start-at' manual loads.
As an example; Vihtavuori lists 3.7 gr N310 as the minimum load for .45 with a 200gr LSWC, giving 827 fps -
http://www.vihtavuori(dot)com/en/reloading-data/handgun-reloading/-45-acp.html
- I prefer 3.3gr, though I'll go up to 3.6 - and for velocities I'm happy in the mid-600's; again, how much power / velocity do you need to kill a piece of paper? I'd shoot ~warmer out of a .44 magnum because of the big case and pressure loss at the flash gap - but the lightest .44 load of N310 that Vihtavuori calls-for, is 10gr for 1,250 fps -
http://www.vihtavuori(dot)com/en/reloading-data/handgun-reloading/-44-remington-magnum-.html
- why? For a lubed 204gr lead SWC, 650 fps will do me fine, and the load will be a lot quieter and less obnoxious.
My go-to load for .357 is 3.3gr Titewad in .38 Special cases, with a ~125gr LRN bullet, sized 0.358". You won't find this load in a manual - because Hodgdon doesn't even list Titewad as a pistol powder. Yet this load is light, clean and quiet - throws the little slug with enough oomph to bowl-over tin rabbits on the steels range, yet almost no recoil in a full-underlug 6" revolver, and very accurate so the guests at the open house can hit what they shoot at. And this is the exact same load I use in 9mm, with a 124gr Lee LTC; enough power to cycle the action, mild, quiet and accurate without too much smoke.
This is why I suggest getting a Chrony - a couple starter loads I worked-out for the .45 when I started loading for it, had disturbing variances in velocity - >100 fps in the 550-fps range over 5 rounds; that's too much inconsistency, and I don't use those loads anymore. Were they dangerous? - I doubt it; they likely didn't have enough powder in them to be dangerous. But I didn't like them, so I don't use them anymore. And I found-out because of the Chrony - it's a valuable reloading tool. Next - a lead hardness tester.
) powder burn rates, there are several other such lists and charts available; certain powders will move-up or down a point or two, but they all pretty well agree. Fast powders are good for light bullets, where you want the pressure to ramp quickly - otherwise, the pressure doesn't build to where the stuff will actually burn. For an example, you could try a load of 3gr H110; but bring a brass drift to push the bullet back out of the barrel, because so little of the powder will actually burn at that low load that likely the only thing pushing the bullet down the barrel will be the primer - and you'll be lucky indeed if it actually makes it out the muzzle; this is very much a "kids, don't try this at home" sorta' experiment.
