If you look ahttp://www.network54.com/Forum/113813/message/1297542006/qb78+.22+tune...changes+continue...What+next.
That was done with just a dremel and a hand drill. I do advise a lathe to do the probe, even better purchase the XP tune kit from archers and not have to worry about recking the bolt.
Others are getting much more then I but this is not bad considering no tools but a dremel and a Drill etc. At 85 with 14.3 cps It should do about 740 FPS. at 69 F is already peaked just about 16 ft-lbs (14.3 cps peaking at 710 fps). Once I get the HDD I hope to have more fun with this. Unfortunately is pretty cold so can only shoot inside right now. Without the HDD it is wasting alot of CO2 so it will be nice to recieve the hdd.
The QB is a realy kewl air rifle with lots of potentional for over stock velocities very easily. Goto archers, pick your qb style, add the XP Tune kit and HDD and your almost ot your goal. If not opening up the barrel port will help and you can easily do some valve work if you want.
If you are thinking about bulking the ar's might be a better price point and you get the target stock! But then its a little bit heavier.