I have a full metal d-boys stock m4 bushmaster stlye AEG. The gun is shooting around 340 fps stock. Today I tried a variety of springs to increase the fps as well as some other little hop ups.
First off I tried a modify s120 spring which i have read to produce around 400 fps. Installed it cronied at 320 fps.
Next I tried another 400 fps spring, same thing around 325 fps. I was thinking i must have done something wrong so i went back to the stock spring and nope, back to 350 fps. The modify s120 is at least one inch longer than the stock spring. I dont know if this matters but i really thought it would put it up to 400fps. I tried a new piston, head, sleeve and that made things worse. Now the nozzle protruded slighly into the hop up and stoped ammo from feeding properly. I have had this box apart about 10 times now and I am feeling dumb as to why with upgraded parts it performs worse. Maybe D-boys just have shitty mechboxs that dont like upgrades.
Any suggestions?
Is the mechbox worth upgrading or should I just build a new one from scratch?
Anyone have a recomendation for a good drop in mech box around 400fps.
Thanks
