Actually I mentioned the green one for use with the A5 set up. Springco doesn't make a green carbine spring to my knowledge.
Believe it or not they DO make a green one (I was looking at their website when I read that post of your's quoted above). And it is for the A5 buffer and tube setup. That's why I asked. So blue it is then for a regular carbine tube?
I kind of feel lucky to have gotten this barrel. Colt made them for the IDF (or so I've heard in the past) at one time with a 1:7 twist so the Izzies could convert and use the heavier bullets like M855. They're supposed to be like hen's teeth.
Yeah, I know rifle ones are longer. Technically the green one can be used on a carbine as long as you have an A5 setup so that is where the misinterpretation of what you said came in on my part.
How do you think the .085" gas port will affect things? It's a little smaller than the one you mentioned (.093").