I only tested it on my friends Tippmann 98, but man was it shotting really well! Some of my other friends it shot better than the Boomstick! It is accurate, shoots far, and is very quiet! I don't know what more you could ask for in a barrel!
None that I could think of! It only broke like 3 balls out of 2000 and it was the bolts fault! But yeah that's all I could think of!
Best damn barrel I've ever seen! Not saying much because I only tested, BUT still! Only few barrels I can think of can campare to the Stone Cold II. Maybe the Boomstick, All American and maybe the J&J Ceramic!