Many 1911s have unramped, unsupported barrels with a huge chunk of the cartridge hanging out. Many have been throated to feed JHP. There should be 1911s exploding everywhere if that were the case.
I'd worry about a G21 going kaboom about as much as I worry about getting hit by a meteorite. About the only way you're going to do that is by using tired and bulging brass or by overcharging the case... both are reloading errors.
With new factory ammo I'd not worry about it one little bit.
As others have said .40 is rather higher pressure than .45, but even then (with the partially unsupported chambers) it's not really an issue unless someone is reloading brass that should not be reloaded or putting in too much powder.