I still recomend the laser punched boges from Electronicstix.com. I had one last over two weeks. I don't use the DC cartos just single. I had one that was old enough to colapse the air tube. But then I don't change them like I should. I hate to use my backup stock. OMG I got another 150 coming and still got 75 in house. LOL paranoid. Yep I am I am.