I just recently built my AR and got a quad rail for it. Looked at my upper and I'm not sure if i can take off whats on now. Does anyone know for sure? Not really looking to screwing up my upper. Its a sota arms 7.62 upper. Thanks!
Why do you want to replace the tube? Whatever it is that's pictured in the center photo, it doesn't look compatible.
I'd go out and shoot it first and see how it works as is.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek
Went out and shot it today and there were no problems. I was wanting the quad rail so I could add a front grip. Maybe a gun smith could give me a better idea of what I need? I'm extremely new to ARs so any advise on what I should do would be a ton of help.