What kind of gun is it an m4?
If so then yes the normal 1 peice hop up will replace the 2 peice. (you will likely have to mod the lowwer reciver to fit the one peice in)
There is a c clip at the front of the hop up that has to come off for the barrel to come out. Also you should at least turn the hop up all the way off or even better remove the screw and the adjustment wheel from the unit so you can tilt the arm out of the unit. Then give the barrel a lil twist back n forth as you pull. I find alot of the china stuff seems as tho its glued in place lol but itll come out with a lil love
There are replacement 2 peices available if you google it