Reloading rule #1: If you change a component, any component, reduce load and work back up to an acceptable level.

Granted, the suggested 3% for these two powders doesn't give you much room to reduce but, that is a good thing, in my opinion.

Listen, physics being what it is, and this is just me, but, I don't think you can get enough H110/W296 in a case that is designed for a magnum load to blow up a gun by creating too much pressure.

Double or triple charges of a fast powder? Oh, yeah, now that can be done pretty easily.

In most cases (as in instances) a full charge of H110/W296 is going to fill the case (cartridge) almost to the base of the bullet. By the time you put enough in it to hit the bottom of the bullet, there isn't enough added to get the pressure to twice what the cartridge is rated for which is what SAAMI says is supposed to be the rated burst pressure of the firearm designed for that cartridge.

Can you get to pressure signs? Yeah, you can get flattened primers and sticky extraction but at that point, you are still nowhere near twice cartridge pressure.

Can you blow up a gun with H110/W296? Sure! Run a reduced load, have a squib followed by a round that goes off at its full reduced potential and you are going to test your frame pretty well.

Now, I need to qualify this statement a bit but, I don't load for the 454 Casul, 460 S&W Mag, so I cannot speak to those cases.

Just my thoughts on the matter though.