I have or have had
1 Magnum reasearch (superb but spendy)
1 Butler Creek (piece of junk)
1 E.R. Shaw ( shot just fine)
1 Volquartsen (had features gm didn't offer)
But I currently have 9 green mountain barrels, in each rimfire caliber ranging from 16.5 inch 17 hm2, to 20 inch 22mag. I love them, have installed probably anohter 15 for relatives and friends. Have not had a single bad one.
I highly reccomend Green mountian.