there are many different opinions on every mod and sometimes they are 180 out from each other. I know I have seen at least 3 or more takes on bolt probes, hammer spring spacers, valve porting etc.
So to compile a decent reference you would have to decide what is correct and stand behind it or include every opinion on the subject. (a truly daunting ask).
There have been a few who have made a decent attempt to bring together all the mods. This one was posted here.
http://www.network54.com/Forum/79537/message/1025125764/my+collections+on+QB+%28long%29
Mike Melick in Iowa, (a noted tuner) has a manual that describes assembly, disassembly and some of the most common mods and a few not so common. If you were to E-Mail him I am pretty sure he would send you the file. He always tries to help whenever he can.
Also as was posted earlier Archer Airguns sells a good book on the whole family of QB 78's.
And last there is a lot of good information here under QB78.
http://www.airguninfo.com/chinese.shtml
Just my thoughts.
Jeff Schock
WB9ZPO
QB78 carbine tuned by CO2une,
QB78 Thumb hole stock
AR2078 mild tune by MM
