Hammer bounce in true hammer actions?

Hammer bounce in true hammer actions?

Joined: September 11th, 2010, 3:10 pm

February 17th, 2012, 11:04 pm #1

Has any of the more technically minded people here researched the phenomenon of hammer bounce in revolving hammer actions? By revolving hammer I mean hammers that turn around an axle as opposed to plunger type hammers as in Crosman 1377 and similar.

Looking closely at a Gamo CO2 revolver and an older Crosman it looks like they have by passed the hammer bounce by using a transfer bar. On the other hand it might just look that way, and the hammer could be bouncing faster than the eye can catch it.

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Joined: June 5th, 2006, 12:49 am

February 18th, 2012, 12:28 am #2

By themselves hammers bounce the same as strikers. The transfer bar doesn't help because
it still connects the hammer and valve stem as long as the trigger is pulled. You'd
have to let off the trigger in a couple of milliseconds to beat the bounce.

But these CO2 revolver hammers do bounce less (than say a 22xx striker) because usually
they're mated to in-line valves which require less force to open and have different
forces acting on them during firing. With a 90-degree valve you'll still have bounce.
http://www.youtube.com/user/Rakemaan?ob ... sults_main
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Joined: September 11th, 2010, 3:10 pm

February 18th, 2012, 1:35 am #3

Interesting to see in one of those vids that they used what seems to be a rebounding hammer. Being more familiar with shotguns, the rebounding feature was the first thing that came to mind when I read about valve bounce. It is a simple self regulating system, and judging from pics it was used in the Giffard CO2 of the late 19th century. Obvioiusly it was rejected in later designs for unknown reasons.

Seems like I will have to resort to the old principle- via experiments you arrive at results. I am thinking of installing a rebounding hammer in 1377 and see how that works out.
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Joined: November 28th, 2002, 6:26 pm

February 19th, 2012, 4:00 pm #4

...I do wonder how useful firearm analogies will prove to be in airguns.

Steve
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Joined: September 11th, 2010, 3:10 pm

February 20th, 2012, 11:41 pm #5

Has any of the more technically minded people here researched the phenomenon of hammer bounce in revolving hammer actions? By revolving hammer I mean hammers that turn around an axle as opposed to plunger type hammers as in Crosman 1377 and similar.

Looking closely at a Gamo CO2 revolver and an older Crosman it looks like they have by passed the hammer bounce by using a transfer bar. On the other hand it might just look that way, and the hammer could be bouncing faster than the eye can catch it.
Shotgun primers probably require less force to actuate than a valve stem. But, shotgun hammer springs are diabolically overpowered. It only takes a comparison between a traditional V spring and a modern coil spring powering the hammer of self loading shotgun to appreciate the range in spring power available.

The Giffard had an external hammer. The design was abandoned and I wonder why. Complexity could not have been the issue, the system only has four parts, hammer, spring, guide with rebound prongs (if a coil is used) and sear. If a V spring is used there is no need for a guide, the spring itself provides the rebound arm for the hammer.

A friend owns a Giffard rifle. I will have to pressure him into letting me take a close look.
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