I think that I'm still not getting my question right.
Assume you have an AR-15 with a 18" - 24" barrel, a rifle length gas system and an A2 stock. If you remove the stock, buffer tube, spring, and buffer, and replace them with a carbine length buffer tube, spring, buffer, and collapsible stock, what effect will that have on the action?
In other words, a rifle upper on a lower with a carbine telescoping stock. If that's what you're talking about, I've done it and it works fine.