Just picked up one of these, and what a great little rifle! Nice grips and rails, collapsable stock, trigger is nice and tight. This rifle feels really solid and looks great. I put 180 rounds through it with no hic-ups whatsoever using both the Hk and Colt style mags(not that theres really any difference between them). I didn't have any scopes that would co-witness with the Hk sights so I put some Magpul sights on it. I really like the look of the Hk sights but they are not adjustable short of filing down the front post. Added the fake can offered by Umarex to complete the rifle. Hope you like it as much as I do.