Matt, it sounds like you're trying to make reloading into Rocket Science, and it really isn't. While the reloading manuals sometimes say "Don't ever change ANY of the components we show here or your gun will blow up in your face and you'll be dead or scarred for life and then you'll be really sorry you didn't listen to us", there is still some wiggle room here.
I think of reloading manuals like cookbooks. Lots of good recipes in there, but every cook changes things a little bit, to suit their own taste. As long as you're not loading hot loads, you have plenty of room to alter the recipe. A slightly heavier bullet or a different primer or thicker brass can bump pressures up, but if you're nowhere near the red line it's not that big a deal. There are a lot of variables involved here, some that are rarely mentioned. But if you understand the basics of what you're doing, what to do or not to do AND WHY, then you're not likely to get yourself in trouble.
Starting off slowly and taking small steps is a good idea, but don't trip yourself up in the process. Most of the loads I use are right in the middle of the starting and top-end loads, then I adjust them from there to suit my needs. Starting too high is bad, but starting too low isn't much better. What you want are loads that are (1) Safe! (2) Consistent and (3) Accurate and repeatable.
I'm guessing you're loading for a 45 Colt. What gun? Give us some specifics on what you're using, what you want to accomplish (hunting, paper-punching or plinking), and we'll help you settle on a good load. There are hundreds of accomplished reloaders here, willing and able to help. For free!
Just a guess, but since you're using AA#9 you're looking at a non-Cowboy-level load, something around 1,000 fps or so, right? In a rifle that would be a fun plinker or target load, and good for hunting small game, maybe even deer up close. I'm hoping you've slugged your bore and measured your bullets to assure a good fit, right? Because all the reading and studying and ballistic knowledge in the world won't help much of your bullets are undersized, you will get horrid accuracy and bad leading. You don't need that kind of aggrevation, especially when you're just getting started.
There is a steep learning curve, so take your time and ask a lot of questions, we were all new at this back when.
To (finally) answer your actual question, a few grains difference in bullet weight won't matter enough to be able to tell a difference. Don't worry about minor variations in lead bullets, that's normal.