I've been using NATS carts since June of last year, so far I like most of all the configurations I've tried, and I've tried all my favorite groupings, even the 27 bugpin mag. I can honestly say this though, TTechs liners are superior. But I don't think it's the actual needles anymore. TTech liners seem to flow better, and they really shine with larger groupings, whereas NATS carts, the larger round groupings seem to be too tight in the tip of the cartridge, limiting its flow. I think it's the way the tip of the nozzle is shaped. I've taken a razor and shaped the tip of NATS to look like TTech and instantly there always better flow. It only takes a few minutes extra to set up but I think it's silly that NATS uses the same size cart for the 11rounds as they do for the 7 rounds. I've emailed them and messaged some "Ken" guy on FB about the issue, I don't know that anything will come of it though. I will say tho, They did fix the tension issue with their O rings, so there's that. Anyway, simple solution; order my larger rounds from TTech. No biggie.