The list will keep growing, I'm sure.
Besides the companies outright boycotting California (Barrett) and New York (the other 5 manufacturers), there are dozens who are taking the less drastic, but still significant, step of asking people to contact their elected officials and express their support of 2nd Amendment rights.
Smith & Wesson and Hornady are just 2 examples that I've covered on my blog. There are dozens more though!