I mean you are simply delusional if you think banning bump stocks will stop casualties from shooters since they can just make a bump stock themselves easily.
I don't think it would make a particularly large dent, but any marginal benefit you get from regulating them will come at the cost of
absolutely nothing to legal gun owners. My original thought was that these things were dumb and useless enough that gun enthusiasts wouldn't feel the need to reflexively defend them at all costs. I was wrong.
Keep in mind that laws can still be effective even if there are loopholes. Prohibition did drop alcohol consumption, and gun registration laws do curb ownership levels,
even though we live in a world where you can literally 3D print a single-fire pistol. I'm not particularly gung-ho when it comes to addressing gun violence through regulation. I think that the root problem here has more to do with poverty and mental illness, which could be better addressed by social programs and expanding healthcare. But the bump stock thing seems like a solved issue - they serve no practical purpose for anyone besides someone looking to fire rapidly into a crowd of people.