The safest way of doing this is to strip your gun down and start replacing stuff. Adding high quality items like reservoirs lubricants, seals, valves, etc etc will give you a huge increase in power. If you feel like risking it though you can try (if you have a PCP or CO2 gun) rigging the release valve to only let higher pressure through, or modify the connecting outlet to allow for a bigger tank (that only works if the gun does not have a specific power setting, and instead just opens the valve for a set amount of time).
Keep it clean and get a stronger spring.
NO
No
you dont
Yes. A&K and one other company make an airsoft gun based on the design of the Magpul Masada.
At your house LOL.
I would highly recommend that you do not make your own airsoft pellets. They might jam and or brake your gun.
An Airsoft gun
no. Airsoft guns could not possibly shoot that fast.
Because you, my friend, have a broken airsoft gun.
Not worth it. You may damage your gun
youtube it