Airgun. 
Washington needs to analyze the rules on these. You can take some big game with airguns bit it's not allowed. I'm not suggesting a moose with airgun and I'm not gonna say they're equal to powder burners by any stretch. However it's been proven time and time again airguns are more than effective on deer sized animals and larger in fact. However not all airguns are equal and they should do it somewhat like archery.
There should be a way to state that a minimum foot lbs energy is legal for some game animals. Airguns are currently not legal in Washington for game animals. But they should be, with some standards with respect to energy and particular animal.
There could be an easy regulation that requires something like 200 ft lbs for deer as an example. That's been proven for years to be good enough...