Okay.. I've sorted a few basic gun issues like wiring and changing a motor in an MP5 but I keep seeing words wot I am not understanding the meaning of so:
What's bushing and how / why do you do it?
What's shimming, is it something most people do in Amsterdam and how how can this help my gun?
How much of a pain is it to change a spring in an AK74?
Any help / advice gratefully received 
Bushes are the things that the gears spin within. Most manufacturers (not all) fit plastic ones initially, meaning that the gears cause stress on them, eventaully wearing them out and causing a failure of the gears in the process. "Bushing" usually means replacing them with higher quality metal ones, like mini bearings, so the gears spin more freely and cause less stress and the metal bushes will last longer than plastic ones. It's a "must do" if you plan on fitting a stronger spring. Stronger spring = more stress on bushes.
Shimming is part and parcel of bushing. In order to make the gears a good fit, with no side to side movement, small spacers, or shims (like mini washers) are fitted between the bushes and the gears. Each manufacturer of gears and bushes will end up with a slight difference, meaning shimming can be a bit of a balls ache. Replacement Marui gears always come with a little bag of shims. For other makes, you usually have to buy them seperately.
Changing the spring in an AK is a doddle if you know what you're doing. If you don't, It'll be a nightmare! If you've not done it before, best to get a shop to do it. That way, if the gun packs up, at least you have a guarantee.
When I want your opinion - I'll tell you what it is!
Hey i've always wondered that too!
Thanks
"I think we are in rats' alley - Where the dead men lost their bones."
Me too... I'm a numpty when it comes to electrical stuff, mechanical mind, you see.
GBBs FTW!!1!1!!!11 kthxbai
mechanical mind, you see.
Hehe! Bushing, shimming and spring changing are all mechanical changes. 
A Proud Member Of 'Team Spleen!' who play mainly at Gunman Airsoft, Tuddenham, Suffolk.
You got me, McV. Hoisted by my own petard... 
Cheers guys! My M1A1 and MP40 are too sweet to mess wth but I've got a Galaxy MP5k that's an utter piece of sh*t - never worked well enough to use - so I may start experimenting on it!
Oh - anyone else got sticky feeding MP40 mags and will a squirt of silicon fix of FUBAR them?