We didn’t know what a “bump stock” was until the killer in Las Vegas on Sunday used a dozen of them to make his job of slaughtering people so much easier.

And we sure didn’t expect Republicans in Congress to get on board this week with regulating bump stocks, which essentially convert a semi-automatic rifle into a fully automatic weapon. The great majority of Republicans in Congress wouldn’t ban the sale of scud missiles at 7-Elevens if the National Rifle Association were against it.

EDITORIAL

So, to our thinking, it was mildly good news on Wednesday — a glimmer of hope — when a significant number of congressional Republicans indicated they might favor a ban on bump stocks. And even the NRA signaled it might, this one time, come around.

We’ll try to suppress our skepticism that Congress might go after the devices, which are such a tiny part of America’s gun problem, just to spare themselves from having to answer for not doing more.

Among the first Republicans to come out against bump stocks was Rep. Adam Kinzinger, who released a statement calling on the Bureau of Alcohol, Tobacco, Firearms and Explosives to reconsider the legality of the devices. Kinzinger is rare among Republican congressman from Illinois in that he occasionally reveals a mind of his own.

Sen. John Cornyn, a Republican from Texas, has asked Sen. Charles E. Grassley, a Republican from Iowa, to convene a hearing of the Senate Judiciary Committee to consider limits on bump stocks. Other Republican senators questioning the continued legality of bump stocks include Lindsey Graham of South Carolina, Orrin Hatch of Utah and Marco Rubio of Florida.

Are they serious or putting on a show? We fear it’s the latter.

In the aftermath of every mass shooting, the NRA’s lackeys in Congress look for ways to look a little less like lackeys, for the sake of appearances. But this time, bending before a furious American public, even the NRA now says bump stocks “should be subject to additional regulations.”

Nobody should believe Congress is serious about banning bump stocks until it does so.

But if it does, it will be taking a small step toward more sensible gun laws — with more to come, we can hope — for a country that is weary of all the dying.

Send letters to: letters@suntimes.com.