Works Amazing... with the correct bucking
This is a huge upgrade over the stock M249 hop unit.It feels premium in your hand, and fits perfectly in my A&K M249.However, when using Maple Leaf hop buckings, the feel lips stick too far in to the feed window stopping any feeding from occuring.It was an easy fix to trim the feed lips so they do not pass into the window.Depending on the buckings you choose, you might not have this issue.After the adjustment, all of my box mags feed flawlessly.Using the ball bearing, the hop unit has 10 adjustment points. Thankfully with the weight of BB's I use, I get perfect hop on one of them.I tried to use the included O-ring instead of the ball bearing to get a more precise hop adjestmen, but it was too thick for the adjustment dial to fit over.Thankfully I didnt need it but I would suggest you have an o-ring set to swap in if you dont want to use the ball bearing.All in all, I'm very happy with the feel and performance of the unit. It's WAY better than the stock unit and is a great substitute if you can't get the Bullgear one.