No,place the bushings back in the SRC GB case,and place the parts goldentrigun listed inside aswell.Your bushings should fit very tightly in your GB case.I lkie to use super glue on the seats of my bushings,and seat them ussing a ballpeen hammer and ratchet extention.You dont want the bushings comming out when you open the GB up.
Here is an excellent guide for GB shimming,very good in fact:
http://www.airsoftsociety.com/forums/f10/how-shim-like-true-mechanic-30461/
Heres another regarding opening the GB for the first time:
http://www.airsoftsociety.com/forums/f10/my-comprehensive-beginners-guide-opening-gearbox-first-time-32341/
Hers a very good one for advanced hopup modification:
http://www.airsoftsociety.com/forums/f10/my-guide-fine-tuning-hop-up-33545/
I hope these help.
Here is an excellent guide for GB shimming,very good in fact:
http://www.airsoftsociety.com/forums/f10/how-shim-like-true-mechanic-30461/
Heres another regarding opening the GB for the first time:
http://www.airsoftsociety.com/forums/f10/my-comprehensive-beginners-guide-opening-gearbox-first-time-32341/
Hers a very good one for advanced hopup modification:
http://www.airsoftsociety.com/forums/f10/my-guide-fine-tuning-hop-up-33545/
I hope these help.