No, I've never heard of them. I've never worked in a machine shop so I'm still learning as I go, project by project. Each project I tackle presents something new I need to figure out.
I did research index drills but 6xD was to short, the they jump to 8xD which is too much and nothing in between. All my research never brought up gun drills which is a bummer at this point. I'm definitely going to look into them further, thanks for the heads up.
I've pretty much got it figured out now, I can do the machining to spec just working on the finish. I finally found the exact reamers I needed, which is dumb in hindsight, live and learn I guess. It probably wouldn't have been that big of a deal for anyone with actual experience in the trade but I'm just flying by the seat of my pants (still).