QB78 Hammer Spacer Mod Lockup

[iconoclast]

Charlie's QB-78 Tune describes using a 1/4" spacer between the cocking block (0800) and the tube plug (2000) to increase power by allowing more CO2.
CO2 tuneup by Craig describes shimming the hammer with 5/8" dia washers.
I didn't have a 1/4" spacer handy, but I did have some 5/8" washers.
So, I used 4 washers to give a little less than 1/4" spacing.
I placed them between the cocking block (0800) and the tube plug (2000) as Charlie described.
It seemed to work, sort of, for a while but then locked up the cocking lever in the forward position.
When I removed the tube plug (2000), I found that my washers had fallen over.
This prevented the cocking block (0800) from returning to it's back position.
-------------------
Are Charlie and Craig talking about different shimming methods?
Should the shim be between the cocking block (0800) and the tube plug (2000)?
Or, should the shim be between the cocking block (0800) and the hammer spring (0700)?
Could  someone explain this mod in a little more detail and how it works?
Thanks,

[ribbonstone]

Not really sure about that post....the only thing I want to shim (if i shim anything at all) is to shim the hammer spring forward.  Bascially, that pre-tensions the spring, increasing it's strength, which makes the hammer smack the valve harder.

Rather than try to write it, will post a pictures (excuse the discolored hammer...I cleaned it up later).

[iconoclast]

Thanks for the pictures.
It makes more sense to do the shims this way.
However, to tell the truth, I'm not sure I need anymore power.
After doing most of the other mods, my QB78 sure seems to shoot with a lot more power already.

[ribbonstone]

Agree...can wack the valve harder and get more power, but it tends to make the rifle into a gas hog.  Does take gas to go fast, but there is a point where you can retrace your steps through the woods  by following the line of empty 12gr. cartidges.   Can think of it as an anti-lost feature for people that don't have a GPS unit.

Best advice I can give:
Pick  speed...mod it to that speed...live happy.