I purchased 3 guns and some accessories from RKGuns.com. There's pros and cons.
Pros - I've had very good gun buying experiences. Prices are often the lowest. So far, all gun purchase experiences have been pleasant. I took delivery at the closest Rural King which saves some money. Not around the corner but the people are nice and I like the store.
Cons - For non gun purchases, customer service from online RKGuns.com (not the store) has been awful. I ordered Magpul mags and they never came. A gun case fell apart and they wouldn't stand behind it. Emails - don't bother. I sent photos, got robot responses that "we're looking into it," but nothing happened. I wound up calling, got put in the "Que" for a long time, and eventually reached people who couldn't help (other than cancelling the magpul order.)
For anything other than actual guns, I won't order from RKGuns.com online again unless the prices are unbelievably good. You have to assume if the item is defective you're stuck, and if it never arrives you'll have to suffer through a long phone wait to cancel the order.