As has been stated by FW,
You will run into this kind of thing as you go along. I have both the 47th, and the 49th edition of the Lyman manual. The loads are the same in both. I also have the current (7th), and the 4th editons of the Hornady manual. The loads in both those manuals list 31.4 grs as max. My old Ideal manual #38 (circa 1951) does not list that bullet and powder combo to reference.
As I said, I never throw out a reloading manual...
If you look a little deeper into the texts, you will see that in this case, Lyman, has used a "Universal Receiver" as a test rifle, and Hornady has used a Winchester M94 rifle.
I think this is where most of the disparagement comes from. I'm not suggesting that either manual is "wrong", or either company has been negligent in any way. What I'm saying is they are using different methods to derive their pressure data. Universal Receivers and pressure test barrels are expensive, far more so than using a regular test rifle. Some companies use only rifles, and some use a mix of each.
A "Universal Receiver", is basically a test block with a pressure barrel screwed into it. These pressure barrels are usually machined to minimum specs, with a chamber that would be found to be smaller in dimensions than your average Winchester model 94 lever gun. The pressure barrel has a pressure port machined into it whereby the actual pressure in the chamber itself can be measured. If I recall, there are 2 primary ways of doing this, but both have the end result of being able to directly measure the maximum pressure that occurred in that chamber.
A massed produced hunting rifle, in this case a Winchester 1894, may have many, many barrels cut with the same chambering reamer and tool setup. This can lead to some "generous" chamber dimensions.
When a rifle is used, sometimes a "strain gauge" is attached to the rifle, but usually it is the fired brass that is examined to "determine" how much pressure occurred in the chamber.
Both methods will work, but each "rifle" is it's own individual, with differing chamber and bore dimensions. This will lead to pressure differences between rifles. You will notice this yourself, if you start loading ammo for same caliber rifles.