Man, sorry guys. I had a bunch of life poop happen and I never got around to closing this thread out. I ended up shooting the gun down and then unscrewing the bottle from the rifle. This caused some other issues, but I was able to disconnect the fill from the gun at least.
I really appreciate everyone's help. I should have clarified, my Guppy has a bleed valve, it works great. What I attempted was attaching only the micro-bore fill line to my SCBA tank which fit and got me all excited. The 2nd SCBA bottle didn't have a bleed valve. Lesson learned. If I can get the manifold unscrewed from the bottle, I'll probably just get another fill setup like the Guppy has, I love the dual gauge setup.
Anyway, thanks for all the replies. Pics for clarification.