The reloading manuals are guidelines (arrr, pirate voice..
), not laws. They show data that was tested and safe in the guns used, and with the components used. Nothing more. What is a max load in one gun might not be in another, even the next ser# off the production line. That's why we are always told to start low and work up.
Now, that being said, most guns, as a group will behave about the same. About the same, NOT identicaly. Many will be identical (as far as we can tell) but some will not be. Some will show higher velocities and some lower with the same ammo. And the same goes for pressure signs.
Also be aware that as far back as the 1970s, there were 3 different identifited burning rates found in H110 powder. So, max loads had to be worked up to and adjusted as needed.
Hopefully today H110 is more uniform, but it still comes down to the individual gun used, the specific batch of powder, the brass, primer, and specific bullet combination determining what is the max safe working load.
Sticky extraction is the "don't go further" sign that is most important. Primers showing slightly flattened faces are a good place to stop. So is slight cratering of the firing pin indent. Primers flattened to the point of flowing out to the edge of the primer cup in the case, and/or flatteneing out the firing pin strike are a serious "back off" sign.
Sometimes these things show up in combination, sometimes only one shows up, first.
Each brand, and lot of components has an effect, and its own tolerances. Some primers are "softer" than others and will show signs of excess pressure when the load is still within "regular" limits. Some bullets have much greater "drag" in the bore than others, raising the pressure of a "regular" load up to the higher end, etc. And the gun itself plays a big part. A tight chamber or bore, vs a "looser" one makes a huge difference.
I've seen guns that showed pressure signs with factory ammo. Seen ones that showed hi pressure signs well before book max, and ones that never did, even with loads well over book max. Been reloading about 40 years, currently for over 30 different cartridges, rifle and handgun.
Each combination of gun and ammo components is an individual, particularly in regard to what is the max load. However, some general things do apply to all, and one of them is, when things start looking odd, its time to use caution.