Well Kevin,
As luck would have it, the test cronograph printout from Mr. Archer for the Gold Service is missing for this .22 cal QB78 but I do remember the velocities being in the high 400's. An XP tune kit was installed as well as a two stage trigger. I replaced the deluxe stock with a Crosman 160 stock from the 1960's. A very easy do, just had to enlarge the trigger well and re-inlet the barrel band area. Everything else lined right up.
With two new powerlets I shot a string of twenty through an Alpha Crony. Here are my results with a "tuned QB78 deluxe in .22 Cal.
String#1 Crosman Premier HP .22 cal 14.2g 30 sec. between shots. 92 degrees
Low 610.9
High 624.0
Ave 614.8
Xspd 13.10
SD 4.35
1. 624.0
2. 619.9
3. 615.4
4. 614.6
5. 613.5
6. 613.9
7. 614.4
8. 612.7
9. 610.9
10. 611.7
String#2 Crosman Premier Hp .22 cal 14.2g 30 sec. between shots. 92 degrees
Low 605.7
High 616.7
Ave 611.3
X spd 10.96
SD 3.31
1. 616.7
2. 613.2
3. 612.2
4. 615.7
5. 611.9
6. 609.9
7. 609.2
8. 605.7
9. 609.4
10. 608.9
A very nice increase in velocities after the upgrades and was shooting 0.5 ctc groups at 10 yards from a bench. This was built in Dec of 2010 so I think if I put a cleaning patch through the bore the group would close a bit. Notice the gradual decrease in MV in the two shot strings. I think if I let the powerplant warm back up I would get an even better standard deviation and spread numbers. There was a 20 minute pause between the two shot strings.
This is the third one I've built for others. I have got to get me one of these! Kevin, are you going to do any more mods to yours? Really like the wood you got on yours. Happy and Safe Shooting!
