Tom, your premise does not hold up. There are more heterosexual married couples who cannot have kids than there are gay couples in the U.S. From your argument, these heterosexual couples are also not contributing and shouldn't be allowed to marry and benefit from it.
The purpose of hunting is to kill and/or capture an animal. If you carry weapons into the wilderness, stalk prey, take shots at them, etc., but you never bag an animal, you are still engaging in hunting.
Shooting bullets into cardboard, on the other hand, is a completely different game with different outcomes.
It is easy to see why hunting might have one set of rules and regulations, or even given its own government sponsored benefits, and why target practice might have its own rules and no benefits. It would be ridiculous, no doubt, for people playing target practice to demand the same benefits that hunters get.
I know this post is a little old, but sticking with this analogy, when the government has decided a cull needs to happen, you don't get money for shooting at deer/coyotes, you only get money when you show up with a carcass.
Why not only give benefits to people caring for children instead of married couples, if that's the goal?