The magazine has no method of locking the bb feeder spring back, so you must hold it down while reloading. It is pretty stiff so it get tiring after a while. Also, there is no convenient hole in the feeder for you to load bbs into. You must load them in the top. This is very difficult with a conventional speed-loader. It is easiest to use the old-fashioned speed loader the gun comes with. However, doing so is very slow and impractical in the field. Before you buy, be aware of the loading difficulty.
On another note, I personally do not think the full metal slide version is worth $20+ than this version. The gun is fairly weighty as it is, and the metal slide just adds more weight, Also, plastic stock slide is pretty durable, feels fine to shoot.
Finally, if your slide locks back a little while firing (when the magazine is not empty), then chances are you overloaded the mag with gas. Release some and that should fix it. Also, HOLD YOUR GG/PROPANE BOTTLE UPSIDE DOWN WHEN LOADING. Seems obvious, but if you try right side up it will not work. That little tidbit is from experience ;)"