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Benjamin Discovery: Turning down to 7 fpe?

May 6 2012 at 5:22 AM

william  (Login williamN)
YC

Does the Discovery have removable transfer ports so I can switch out for a smaller dia. one?

I am assuming to get the flattest shot string that along with backing off the hammer spring that a smaller transfer port would also be needed?

Anyone with experience with a Disco care to guess how many shots within a 20fps spread I could get with the rifle set at around 7 fpe?

 
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tony
(Login wt157)
YF

If you put a weaker hammerspring it does not have the...

May 6 2012, 5:46 AM 

power to open the valve at high pressure, smaller transfer port sound better to me.

 
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Michael Chavka
(Login haywire2)
YC

Have you considered running your Discovery on CO2?

May 6 2012, 7:06 AM 

In the summer, I run my Discovery(s) on CO2. It's self regulating, and easily increases shot count (.22 cal.) to well over 60 shots with an average fill. My .22 cal. shoots 14.3 grain pellets at 500 fps which is 7.94 FPE.

Regards,
Michael Chavka

Success is not an entitlement.

 
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Daniel
(Login dan1358)
YF

Discovery on CO2

May 6 2012, 9:36 AM 

How much quieter does this make your Discovery over HPA? Have never run my Marauder .25 on HPA yet, just CO2. Man is it quiet! I only get about 13 dead on shots and then I have to refill or use the mil dots for elevation. Thinking about getting a Discovery too. Would just use CO2 also, but was wandering if I would have to put on the "silencer" thing.

 
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Steve in NC
(Login pneuguy)
GM

For any given muzzle velocity/energy, CO2 tends to be louder than air. Not quieter.

May 6 2012, 12:14 PM 

That's simply because CO2, with its lower pressure and higher density, tends to be less efficient and thus requires the expenditure of more gas for any given velocity.

More gas = more noise.

Effective hammer debounce will help tame the muzzle blast of both air and CO2 (by improving efficiency and reducing gas expenditure), as (of course) will a good LDC like the Mrod's shroud.

Steve


    
This message has been edited by pneuguy on May 6, 2012 12:16 PM


 
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Steve in NC
(Login pneuguy)
GM

The Disco uses the same transfer port as the 22xx series, and it would...

May 6 2012, 10:51 AM 

...certainly be possible to make a custom version with a restricted ID, but I don't know of anyone who does. Another (easier) option would be to simply reduce hammer spring power, then reduce fill pressure to get an acceptable shot/velocity curve.

The best option would be to install a regulator, which would make 150 shots per fill easily possible in .177, 200 in .22.

Steve

 
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Eric
(Login oldshooter)
YC

About the regulator....

May 6 2012, 11:33 AM 

Hi Steve,
How hard to adjust the regulator?And does it have to pair with the power adjuster?
Thanks
Eric

 
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Steve in NC
(Login pneuguy)
GM

If you mean this regulator...

May 6 2012, 12:03 PM 

http://www.airgunsofarizona.com/DiscoReg.htm

...then pressure is easily adjustable via the setpoint nut accessible through the vent slot.

As for power adjustment, one of the really nice advantages gained when a regulator is installed is the ability to quickly and easily adjust power by simply changing the hammer spring preload. So while an adjuster really isn't necessary, without one you'd be missing out on half the fun of having a reg' in the first place. happy.gif

Steve

 
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william
(Login williamN)
YC

Re: The Disco uses the same transfer port as the 22xx series, and it would...

May 6 2012, 4:32 PM 

In the past, on more than a few pcps, if I tried to drop the power too much with just the hammer spring I got a rise and fall velocity and no real flat spot.

The reg sounds interesting. I'll check that out.

 
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Jeff P
(Login pad617)
YFOT

William if you are interested in a reduced transfer port email me...

May 6 2012, 12:12 PM 

pad617 at cox dot net

Jeff P

 
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william
(Login williamN)
YC

Re: William if you are interested in a reduced transfer port email me...

May 6 2012, 4:37 PM 

I haven't purchased the Discovery yet but if I do I will definitely contact you.

 
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