Got this for my Echo1 P90. Already had an 85 spring and a box mag installed on my gun, it was a great CQB bullet hose but I wanted that extra accuracy. Installation took less than 5 minutes (may take more if you are unfamiliar with tearing down hop-ups). Lubed the barrel and gave it a try. Accuracy was dramatically increased, 4-6 inch groupings at 75 feet was amazing, 10 inch groupings at 75 feet on full auto was even better. The hop up unit seemed to be less effective though, and if I had more than 1/3 hop the BBs would just sprinkle out 10 feet in front of me. After a couple test shots it jammed, 2 BBs fed into the barrel at once. Usually the gun just shoots them out, but because it was a tightbore they got stuck in there pretty good. Used unjamming rod and removed them. Has been happening every 200 rounds now, very annoying. Switched back to my stock barrel and problem solved! Too bad that such a great quality barrel has to jam on me so much.
Amazing accuracy for such a short barrel
Easy hop up installation
It's Systema, you know it's good stuff
Jams on my gun very often (maybe because of box mag though?)
Must keep it very well lubed to keep it from jamming
Acutely affects hop up setting, dont use too much