PetahW pretty much nailed it.
You see, there is pressure, and there is pressure. The Rem series pump and autoloaders, the Browning BLR, and a few other front locking designs will handle a higher pressure than the "traditional" rear locking designs like the old Winchesters/Marlins, etc.
But in this case, "handle more pressure" means that the actions will take a higher pressure before stretching, or blowing up. It does not mean the guns will work properly with higher than standard pressure rounds.
Modern brass (in a properly supported chamber) doesn't let go until well above the max working pressure for ALL cartridges. Somewhere well above 60K psi if I remember right.
Well before you get to that point, cases swell and stick in the chamber. And it is at this point that the pump, lever and semis have troubles, compared to the bolt gun.
There are two phases to extracting fired cases. The first phase (Primary extraction) is pulling the fired case away from the chamber walls. The second phase is pulling it out of the chamber so it can be ejected.
With normal pressure loads, the brass springs back from the chamber walls a tiny bit, allowing normal extraction. Primary extraction normally occurs when the camming action of the bolt head unlocking moves the bolt head back slightly, pulling the fired case with it. This breaks the remaining grip of the case on the chamber, and allows it to be easily withdrawn, then ejected.
Now, when you shoot an overpressure load (above proper working pressure, but still well below the level at which the case, or the gun might let go), the brass is, in effect, hammer welded into the chamber. While the case still springs back away from the steel slightly, due to the high pressure, it is still gripping the chamber much more tightly than it should.
The mechanical force needed to rotate the bolt head is increased, when this happens. Lever, pump, and semis all rely on mechanical force inline with the bore, a portion of which is being converted to perpendicular rotational force to unlock, and the rest of it to move the bolt to the real after it unlocks.
A bolt action, with a large bolt handle, perpendicular to the bore allows the shooter to exert a LOT more rotational force on the bolt than the other designs, overcoming the increased adhesion of brass swollen from too high pressure. And, of course, there is a point where too much pressure will defeat even the bolt action's ability to extract the fired case.
This is why, when you are working for the ablsoute maximum pressure ammo usable, the bolt gun has an edge over other designs. Note that here we are talking about above standard pressures, but well below the pressure range where damage to the gun could result.
The standard "max" pressures, including "max loads" in reloading data is that pressure level which 1) is inline with industry standards for the cartridge, AND provides normal working function for the gun.
Individual gun tolerances being a variable, listed max loads are below the point of extraction trouble (or any other trouble) in the test guns. So they should be safe and work properly in all guns, BUT may not be. Highly unlikely to blow up any gun in sound mechanical condition, but very likely to cause functioning issues. That's why one ALWAYS starts low, and works up in small steps until the max for your particular gun & ammo combination is reached (if you go that far).
A hot load that functions fine in one gun might be too hot, and give sticky extraction in another. Even identical models of guns can have variations in how much pressure they will take before giving extraction troubles.
The standard pressure signs used by reloaders (flattened primers, cratered primers, expanded case heads, etc) can all occur at different points in different guns. Sometimes some of these occur in a particular gun below max working pressure, because of the tolerances of the gun, AND the ammo (particularly the brass case).
Some guns and ammo combinations can reach, and even exceed the listed "max" levels without showing any of the usual pressure signs. That is why the listed loads, and fired case pressure signs are all guidelines, not rules or laws. Arrrr!(pirate voice)
There is one pressure sign that absolutely should never be ignored, and that is sticky extraction. And sticky extraction can happen at a point below listed max levels, if the combination of brass, load and gun that YOU are using line up just right. Some lots of brass are softer than others. This means they are prone to stick at lower pressure than "harder" cases would. Again, this is why the max listed loads are guidelines.
No matter what pressure it happens at in your gun (and it can vary with different batches of ammo), when you get sticky extraction, STOP. DO NOT INCREASE the load any further. BE a good idea to back off a bit from that point, too.
If it takes noticeably more force to work the pump on your 760, you're done. Not matter what pressure level you are at, at that point, tis time to stop, and back off slightly. If you want, or need more, tis time to go to a different cartridge.
I am thankful I did not get hit in the face with the bolt. I still cant figure out why it did not hit me.