Colt SOCOM barrels are also heavy barrels.
Daniel Defense Socom barrels are also good to go, if you can find one.
Brownells sells a complete DD Socom Block ii clone upper with DD's heavy socom barrel. It's rarely in stock though. I managed to snag one and I've been truly blown away by it's accuracy using Black Hills 77gr OTM.
https://www.brownells.com/rifle-par...om-upper-receiver-14-5in-5-56-prod136059.aspx