It ironclad should be what you look at.
Because that controls the player's experience of misfire.
Absolutely not. Because if you misfire, you literally can make your weapon EXPLODE.
So...no, it really really really is not that it doesn't matter. For more complex weapons (misfire 1-2, even 1-3 or 1-4!), at 4 attacks per round, you would literally misfire more than once every other round.
This faulty logic is precisely what leads to the problem here, Lanefan. When you only misfire 5% of attacks and you only make one attack a round, it's no big deal. When you misfire 10% of the time and you make four attacks per round? It could not matter less that your per-attack chance remains unchanged, you are going to experience misfires at an incredibly accelerated rate.