rolltide90

What length gas system would you recommend running with a 20" barrel? I called GA Precision and they said they normally run mid length tubes.

I am thinking about having a barrel custom turned and was wanting to use a .875 gas block but the only guns I have seen run the .875 gas blocks are Armalite. I am using a DPMS style bolt and was wondering if it would function properly with a Armalite style gas system on the barrel. Anybody have any answers?