Currently these are the only 2 specials in game that can roll 4th times the charm and Deconstruct. 2 ammo refunding perk, and given the small mag size this mean Deconstruct will proc around your 3rd or 4th shot and refund 1 round. For the Uzume this means every 3rd shot you land refunds 1 round and if all 3 shots plus your next shot are crits then you get 2 more rounds giving you a 7 round mag. Then if you continue to land 2 more shots you get 1 round refund and assuming all shots were crits your next crit will refund 2 more shots, giving you a 10 round mag. I believe this process can repeat 1 more time giving you a 13 round mag before reloading. TL;DR you can triple your mag size while only burning through your initial 4-6 shots, basically tripling your reserves since both perks give ammo from thin air.