I have to be honest with you, I think it's really an oversimplification to talk in the simple terms of "pro-gun" versus "anti-gun." There's a lot more nuance to this issue on both sides. For example, I come from a libertarian-minded family that I would call "enthusiastic" about guns. I'm the only man in my family who doesn't own one. But even my brother, who is a strong defender of second amendment rights and is a shooting instructor, advocates for a licensing system similar to the way driver's licenses work. That is, no one is taking your guns away. But before you can own or use one, you must be properly trained and screened. You absolutely can own a gun, but acknowledging the reality that it's a potentially dangerous device, much like an automobile, you have to prove you are qualified first. I think this is a very sensible approach. Much of what people call "anti-gun" positions on the left are not about banning guns ("assault"-style weapons being an exception) as much as requiring citizens to demonstrate their capability and intentions. Bernie has even defended gun makers and sellers against being held accountable for misuse of their products. I actually disagree with him on this--you can sue McDonald's for burning your mouth on their coffee, you can sue Cuisinart if your kid electrocutes himself on their toaster. I think you should be able to sue a gun manufacturer if their product causes bodily harm to you or your associate; Bernie doesn't, or used not to. But there you go.
https://berniesanders.com/issues/how-bernie-pays-for-his-proposals/
There's little evidence that his proposals would adversely impact businesses, and much to the contrary. Raising the minimum wage (which he would do gradually to prevent shocking the economy) raises the wage floor for all workers regardless of income and also puts more liquid currency in circulation in the economy (as opposed to it being concentrated in savings or otherwise out of circulation). This can only be a good thing. As for larger corporations: they really don't need any help. Hillary's thing about Boeing and the Export-Import Bank was literally laughable. As in, I literally laughed. The American national religion is "free" market, trickle-down capitalism: we insist it works in the face of overwhelming evidence that it really doesn't. Regulated economies in Europe prove much better equipped to avoid and mitigate recessions, as in 2008.