Had the full stock version of this AGM shotgun some time back. Tested and fired @360 fps using .20's, and is very accurate with .25's. I attached a short RIS on top and used it with an RDS. Very fun to shoot and is light, which is a welcomed change after hauling all those full-metal AEG's. The hop-up is effective, but I didn't need it with .25's. I don't remember, but I believe it overhopped .20's even when off.
However, the gun had a flaw where the hop-up chamber wouldn't prevent a bb from falling into the receiver and rattling around. After a while, enough bb's fell into the internals and jammed the pumping mechanism to the point where a part broke. I took apart the gun and it's all plastic inside (except for the spring, of course). There's a nub that should have prevented the bb's from falling into the gun, but I guess someone left off a small tensioning spring at the factory. Doesn't seem like a frequent issue, based on the other reviews, but it did destroy my gun.
In summary, a very fun inexpensive gun to use. Surprisingly good performance. However, because the internals are all plastic, I wouldn't expect the gun to last. I'll probably get another shotgun, but will be looking for something with metal internals.
Thank you for the review! I am very happy that you enjoyed this shotgun, If you wanted to look into something a bit sturdier, check out the A&K M870 PUMP ACTION METAL SHOTGUN.