OLYMPIA — A Washington state Senate panel has approved a bill that would ban trigger devices that allow semi-automatic rifles to fire more rapidly, similar to the ones used in the Las Vegas mass shooting. The Spokesman-Review reports the Law and Justice Committee approved the bill after rejecting a Republican bid to allow them to be sold if the purchaser passes a federal firearms background check. The devices are known as bump stocks or bump-fire stocks. They were used to increase the firing rate of some rifles used by shooter Stephen Paddock last year in Las Vegas. Washington Republican Sen.