Double Down costing 1 Cartridge instead of 2 hurts the skill thematically

[mallleable]

Single cartridge Double Down has been throwing off my muscle memory a lot since I've been getting back into playing GNB. While I think it's fine to make GNB a little less strict when it comes to cartridges, I'm not sure if reducing the cartridge cost of Double Down was the best solution. I would prefer if the cost went back up to 2 cartridges, and GNB get a new skill that allowed them to generate cartridges during down time. Like a 'Reload' GCD that has like a 3 second recast time, and does 0 damage, but grants 1 cartridge.