I punch my tanks, and it does dent them a little, but I've never really had a problem with fitting. Just lube up the rings with a drop of juice first. And when I need to refill, I just slide the threaded side into the tank and do it that way. It actually works a lot better, and you can get more juice in the tank. Then just slide it back in place and wipe off the bottom. I'm sure that can take a toll on your connection over time though. I punch up to three holes in my cartos without leaking or fitting issues. It works great for me. At first, I was taking the cap off to fill, and putting the cap back on always caused horrendous flooding. Then I was sliding the carto down and filling from the top, and that worked, but only ever filled my tank about 60%. Doing it from the bottom, I can fill the tank completely, AND never have to remove my drip tip to fill. The only problem I ever have now is air flow. Because the connection on my Provari is flush with the top of the juice well, the tank will sit right on top and block air flow. But then I just slide the tank up ever so slightly and it's fixed. Does anybody else do this? Because it seems everywhere I look, people are sliding down and filling from the top.