i have a G&P Metal M4 Rapid Fire II. i want to upgrade my spring to the Systema M130 Irregular-Pitch. can i will do it?
G&P Metal M4 Rapid Fire II Assault Rifle AEG
the full name off the spring is
Systema M130 Irregular-Pitch Airsoft AEG Power-Up Spring (420~450 FPS)
and if i can. do i need to upgrade more stuff in the gun?