First off hi everyone!

Well I got my son his first pellet gun for Christmas the m4-177.
First thing I did was took the gun apart to install the ftp kit for him. Well I got
Called into work so left the gun on my work bench and come home to parts all
Over the place! I know I know my wife was looking for something and knocked the parts
Flying. Now here is my problem I can not find the hammer weight or hammer spring :(
The gun is the Usa model btw! Now I have a few other guns around all crosman btw. Can I use
The weight and spring out of any other gun? If not where can I get replacements?
Thanks in advance