Discussing Hammer/Striker springs .......... ?

[Motorhead]

While NOT new to air rifles ( Springers for 30 years ) ... am just getting my feet wet in PCP / Co2 / HPA types.

Likely this subject has come up over the years but not finding much if any chatter about question at hand, so if you know something and willing to take the time sharing would love the input !!

**Having used and modified MANY paintball markers over the years that in design share many the same type parts and operation principals.  Case in point being how PB guns near ALL manipulate hammer/striker SPRING preload finding a specific FPS rating or used to fine tune efficiency between regulator pressure within gun and getting the best flow from valve with spring installed.  ( Found PB markers to be VERY spring. hammer weight & exerted force sensitive for optimized efficiency )

** Why do we not see spring preloader adjustments on the PCP family of guns  ... or do some ?

Thank you,
Scott

[rsterne]

They are a very common AFTERMARKET item.... I presume the manufacturer doesn't want you fiddling with the gun, so they don't fit them, in general.... In order to get the best "bell-curve" you not only have to adjust the preload, but also the fill pressure in conjunction with that.... The Marauder has not only a hammer spring preload adjuster, but also an adjustment for the hammer travel and one to restrict the flow from the valve.... The combination of those three adjustments allows the gun to be tuned for various power levels using different fill pressures as a result....

Regulated PCPs (which are much less common) can be tuned over quite a large range of velocities by just changing the hammer spring preload.... The limiting factor is at the bottom end of the velocity range.... If the hammer strike is too weak, then when the tank pressure drops below the regulator setpoint the velocity will actually increase, rather than decrease.... This sets an effective lower limit on this system on regulated guns....

Some PCPs do have velocity adjusters that operate differently.... The Korean guns use a threaded collar on the back of the valve that physically limits how far the hammer can open the valve.... It has gear teeth on the outside of it and is turned by a geared thumbwheel on the outside of the receiver.... It is apparently very effective, allowing the gun to operate over a very wide power range.... but I have no idea what the resulting shot string is like....

Bob

[Motorhead]

Bob,
Thank you for taking time to respond.  Reading your QB thread you do indeed have a good grasp on the dynamics of valve chamber pressure and force it puts on the sealing face of valve as pressures differ.  More pressure within valve HARDER ya got to hit it opening.  Increases in striker weight increase open dwell time of valve where lighter weight decreases dwell time.  Spring pressure part of the package.

Yea, know this concept pretty well myself.

** So, good to know having pre-load adjustable is indeed still a Must have for serious tuning.

Thanks !!

[Ribbonstone]

One  difference is that the pressure of CO2 isn't really changeable...as you whack the valve harder, the valve lets go of more gas. You don't get the option of decreasing or increasing the gas pressure, its pretty much whatever the temperature decides. So with co2 (or those using regulated air), smacking the valve harder is a matter of changing dwell time and releasing a longer burst of gas.

Add the variable with PCPs that the harder the whack the valve, the higher the fill pressure can be.  So its not just letting go of more air, but allowing the use of higher pressure air. So can increase fill (so long as not over the pressure limit of the air tube) as you increase the smack to the valve, resulting in a short blast of higher pressure air.

OF the two, the short blast of high pressure air gives both more power and more shots per fill.

[rkr]

Bob, in reference to that collar and korean guns - do you know if AR6 serie of guns have that?

[rsterne]

Sorry, don't know.... There was a post in the BB forum, I'll see if I can find it....

Bob

[rsterne]

Career 707.... Here is the thread....

http://www.gatewaytoairguns.org/GTA/index.php/topic,20463.0.html

I don't know what other Korean guns use a similar setup....

Bob