just wondering.
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just wondering.
Never seen anyone make one.. but,..... the right balance of hammer weight and spring tension on the hammer and you can eliminate most if not all hammer bounce.
Bruce
If you look at one of the units being sold- it only appears to be cap for the hammer pin- likely with a rubber grommet inside. That being said, any type of rubber grommet that has a protective costing to reduce wear should do the same thing. I do have to say that some of the claims I have seen for this type of device ('debouncer')- i.e. double the shot count, no reduction in power, would appear to be a bit optimistic. I think the "bstaley mod" that Bob posted up is likely a better solution- allows for the specific output to be tuned and requires nothing other than some o-rings and maybe some glue to hold them together so they can move/reposition themselves.
I'm forgetting the guy's name now, but one of the gurus of airgun invention came up with a U-shaped hammer debouncer for the QB years ago and Archer Airguns sells it with a kit:
http://www.archerairguns.com/QB78-HDD-p/qb78hdd.htm
Being a DIY-oriented sort of guy, I spent a lot more of my time than I should have in trying to duplicate his part. Took me a few hours - and I charge $50/hour for my time when working with musical instruments, so I guess you could say it cost me 5 times as much as Archer sells them for. But it worked out well and I don't mind as I love making things work and learning from the experience. Here's a few pictures of what I came up with, made from some O1 tool steel, a lot of filing and bending and fussing to get it right. Works very well. I've also added a single O-ring between the hammer and the steel valve retaining block (mine's a heavily modified HPA QB78), the ring being 0.060" thick, leaving about 0.045" of the valve stem proud of the O-ring. That evened out velocity a bit and quieted the action a lot, while reducing wasted air. Anyway, here's the pictures to revive this old thread. Hope this helps.
http://www.luthier.ca/other/forum/QB...debouncer1.JPG
http://www.luthier.ca/other/forum/QB...debouncer2.JPG
http://www.luthier.ca/other/forum/QB...debouncer3.JPG
Did you happen to have any "before" and "after" pellet velocities?
Not really, as I didn't install the debouncing device to change velocity but rather to reduce air wasted per shot. Higher shot count being the goal. I was working on the tune to get it down to just below 20fpe, as the gun came to me shooting just a few shots at about 28fpe and I don't need it anywhere nearly that powerful. Or loud. So I chopped off some hammer spring and added about a 6mm long brass preload shim. Took about 30% off the hammer itself with a grinding burr in a Dremel, carving away behind the head and cutting off the sides and bottom as well, leaving about 1/4 of the circumference in contact plus two small corners about 1mm wide each. Lower friction, more consistency. Lighter hammers seem to work for me in modding my previous PCP carbines, a Brocock Atomic and a 2240, so no reason it wouldn't work out the way I wanted with the QB78. I'm very happy with the tune, but await a Ninja 13ci bottle connector from my friend Rick, a machinist, as I want to put the bottle below the cylinder not in front of it. This is to be a backpack-able take down rifle.
Anyway, at a guess I'd question whether a debouncer would have much effect on velocity. More likely it helps a bit with consistency of air use from shot to shot. As does the 'bstaley mod' - adding O-rings as needed to tune hammer depth of impact on the valve stem. Oh, but my target velocity I should state as being about 700fps with JSB Exact Heavy 18.13gr, or 775fps with JSB 14.39gr, either way being just barely legal per the HFT 20fpe limit.