I don't belive this test .....they are getting 3k fps out of a 14.5? I'm pushing the piss out of a 55 grain bullet oUT of a 20" barrel and getting 3100 fps .....yet they are getting close to the same velocity with 5.5" less barrel but say that speeds drastically drop 300fps in 1.5"? Not buying itHere is the article I read showing the averages of five shot groups from 10.3", 11.5", and 14.5" barrels.
https://www.ar15.com/archive/topic.html?b=3&f=118&t=509733