I'm brand new to the airsoft scene and I'd love to know if there are any external or internal upgrades for the jing gong mp5sd but apart from that hello I'm Dylan
Loads of stuff available in and out, google is your friend, depends what look you want to go for and if it actually needs internal work.
I ran a JG MP5 as my first RIF for a year and half on a massive 9.6V NIMH battery that filled he whole fixed stock, rate of fire was insane always got looks!
The standard innards finally gave up and stripped a piston but I think that shoes they are good kit for the price!