Which Can will be the best fit for a 6.5 Grendel SBR? Ultra 5, 7, 9? According to this thread on the Grendel forum, it's the U5 30cal... http://www.65grendel.com/forum/show...quot-and-6.5-Grendel-Preliminary-Test-Results "The 5" Ultra seemed to be the quietest overall when taking the ejection port area and gas vent holes into consideration, since the 7" builds more back pressure. The 7" Ultra of course is more quiet at the muzzle, but louder at the bolt carrier gas vent holes." I guess I'm looking for confirmation from the source before I commit to the 5". The 9" length is not a problem, and I'd run it if it was noticeably quieter. Your comments and recommendation are appreciated.