Things I liked: Weapon is well built and shoots straight. Magazine is interesting. CO2 change outs are a snap
Things I would have changed: Accuracy drops off after 50 feet, but this is an SMG. Silly not to have a full auto feature, especially where this is Umarex.
What others should know: Took a moment to figure out the folding stock. It's pretty, but get yourself an Umarex Steel Force or EBOS if you want full auto.
Things I liked: Nice length for a military style air rifle. Very accurate at 100 ft. Grouped 8 inside 1/2 inch. Magazine is interesting, looks like a Pistol revolving mag. Plenty of tactical rail for attachments. Trigger pull is easy.
Things I would have changed: Dual CO2 is nice, but the key system is ridiculous. Someone at Winchester/Umarex needs to devise a better system. The Winchester M14 (which has the same chassis as the MP4) has a slot for the key inside the magazine.
What others should know: Don't lose the key! Flip down sights need work.