Well, they can't have everything. Heavy clip stays heavy clip. Eat too much cake and you'll gain a few pounds, making you heavier.
That was a joke, thanks for coming.
So heavy clip... Imagine a box magazine, like for an automatic rifle. It has to be the same form factor as a normal container, but you want to add weight to reduce recoil. So you add some dummy rounds made of osmium (heavy stuff). Cuts recoil nicely, but leaves less room for real bullets.
tl;dr I think the recoil reduction and lost ammo should be proportional.