Quoted:
9.5" is an interesting choice. Is it carbine or pistol length gas system? I thought 10.3" was the shortest you could go with carbine gas. FWIW, I'm going 7.5". A pistol should be a pistol was my reasoning. Now if was for a SBR lower, I would probably lean pretty hard toward a 10.5", but no SBR for me
The 9.5" from Blackhole Weaponry is a pistol gas system. They use a 3 land polygonal rifling which I think I read somewhere is supposed to help with the velocity issue.
Now earlier I said I was gonna go with the DD 10.3", but I had an impulse buy today and went to Rainier Arms to pick up a 10.5" White Oaks barrel. The reason being is because I hate waiting....the 9.5" is on order, and I can't wait for a DD 10.3".....I want a barrel TODAY! So the WOA 10.5" will hold me off until I get a chance to try the 9.5".
FYI: What's nice about Rainier Arms is since I bought the BCG and barrel from them, they are going to help me headspace my upper to ensure safety...Even though I bought them at different times (albeit all parts are still new and unused).