Nothing wrong with using data from the Hornady #9 manual. The #9 manual listed loads for 7 bullets and the #10 manual list loads for 10 bullets.
Meaning the average data for 178 to 180 grain bullets changed because they have more 180 grain bullets listed in the #10 manual.
Below a link to a...
Using Cream of Wheat in bottle neck cases can cause problems and pressure spikes if it clumps.
Many reloaders still use COW to fire form cases because it blows out the shoulder more with bottle neck cases.
Having said that I now use Trail Boss with all my rifle and pistol reduced loads simply...
There are two ways to tune a rifle for accuracy.
In the military you tune the rifle to shoot issued ammunition.
With a commercial off the shelf factory rifle you can reload and tune the ammunition to the rifle.
Both methods control how the barrel vibrates and the accuracy.
Start with checking...
Its a "No Deal" if you can't buy it.
"Out of Stock, No Backorder" at the link the OP posted.
Below a very good top rated tumbler.
Lyman Pro 1200 Tumbler (115-Volt) $47.99
https://www.amazon.com/Lyman-Pro-1200-Tumbler-115-Volt/dp/B000KKEPOW
Lyman Turbo 1200 PRO Sifter Case Tumbler 110 Volt...
Below is what happens when you fire old surplus click.................................bang Pakistani .303 British ammo and do not wait for the bang before opening the bolt.
This happened during a Mad Minute rapid fire and the shooter was not injured but the magazine was blown out of the rifle...