I'm a white guy in his mid-20s, and I'll chime in... YES, I've witnessed racism at gun shops and gun shows. I had a guy at a gun show with Nazi memorabilia. He showed me an Adolph Hitler postcard and said, "It would make a great gift for your friends in Haifa". Except, oh wait, my Israeli friends are from Haifa.
I've also witnessed a dealer defer a black customer to guns that were "more in his price range" (ie, Jiminez and a bunch of saturday night specials). I also listened to another gun store employee talk about how glad he was that he had a CCW " 'cause one time this black came up to him who look like he was up to no good."
Remember that some gun owners who embody the typical "stereotype" think everyone is like them: White, Republican, Born-Again Christian, SUV-driving, a hunter, owns a big dog, etc. When their bubble is burst, they may not know how to cope. Or they may just continue to live in their bubble where they think that people who "choose to be gay" want to take away their guns, slash the tires on their H2, and pin their eye-lids open so that they can force them to read, "The Origin of Species".
So yes, racism does still occur within the gun community, but then again, it occurs in the community at large. For our part on THR, we try to combat it (note that unlike other gun forums, we don't take kindly to gay bashing). I'm sorry that you had to encounter it, but rest assured, incidents like this will diminish as time moves on.
As for me, I'm off to read GQ, then head to bed...