I have some sorted suggestions. None of these should be taken as supreme directives, but all of them seem to be worth sharing.
You are brand new to this game and you are starting with .40 S&W and Unique. I don't like EITHER of those for a brand new handloader.
.40 S&W is the least forgiving of any modern handgun cartridge in existence, for a number of reasons.
Unique is one of the most popular powders of the last 100 years and most folks who are older than 40 will cling to the stuff to their GRAVE but here in the modern world, there are better choices. Unique does great things, but it SUCKS to use in any powder measure. It's the physical shape of the flakes... it has major problems metering a consistent charge in any known tool.
If it were my decision to make, I'd start you with .38 Special and, well, almost any other powder on Earth.
As for published data and the variances... this is something you will see often. It is mostly related to the differences in components, test units and the goals of the tester when collecting the data.
Especially if you are new at the hobby...
Especially if you are working with the FOTY cal...
Especially if you are trying to meter Unique from a volumetric measure...
...your best bet is going to be to take the lowest of all the max loads you can find specific to that bullet weight and reduce it by 10%.
Make 10 rounds at 5.8 grains.
Make 10 more at 6.1 grains.
10 more at 6.4 grains.
10 more at 6.7 grains.
Make some even warmer if you wish.
When you take your new rounds to the range, start with the 5.8 loads and shoot them. Make sure each shot puts a hole in the target. Notice if the pistol seems to feed them. See how the brass is ejected, if the pistol can eject and feed them. Closely examine the brass and look for signs of stress around the case head and the face of the primer.
Then, and only then, should you shoot the 6.1 grain loads -- and repeat the process of close examination. Notice how far the brass is chucked and maybe how the blast and felt recoil compare to the first loads.
If all of these pass muster, try the 6.7 grain loads. Same, same same.
At some point, if all the ammo you brought appears to be safe, see if you can find a trend in any of the targets. Did any of them seem to offer a tighter group? Is there a certain "feel" or velocity you are attempting to attain? Ask yourself what your goals are and if you can reach them without getting to ANYONE'S max load. Not that you shouldn't approach a max load, just have a reason to do it and have a process to get there.
And do a LOT of checking of your powder drops if you are going to be metering Unique. Hodgdon Universal Clays does a pretty darn good job of being a more modern equivalent of Unique, and it meters much better. It also has the Hodgdon online reloading data center behind it, which is LIGHT YEARS better than what Alliant offers in the form of "load data" from their online "resource."
(I love Alliant powder... I hate their web resource)
In .40 cal? I use Power Pistol.