Thank you for all your opinions.
Actually, I don't have enough budget to buy any toys after buying a new car couple months ago.
But I will be glad to help someone making the internal spare parts of firing mechanism of GBB M16 or M4 rifles. But no promise on how fast it will be done for I will do it after work on available machines.
I do this just for gaining some knowledge of GBB firing mechanism and knowing some new friends in Canada airsoft community. Just provide me the materials and drawings or the old parts. I can make it precisely with in ~.0005" tolerance.
In the near future I will build my own GBB C7A2 or C8A :-)