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PostPosted: Fri Aug 07, 2015 10:58 pm 
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Haven't tried just reducing hammer weight on an otherwise stock 2240. But my guess would be that there would be some increase in shot count and possibly a reduction in velocity, though I'm not sure about that second.


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PostPosted: Fri Aug 07, 2015 11:31 pm 
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The effect is similar to cutting a coil or two off the hammer spring.... an increase in shot count with basically no loss in average velocity over the string.... The first few shots may be a bit slower, but a much flatter string than stock....

Bob

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PostPosted: Sat Aug 08, 2015 12:32 am 
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topher1266 wrote:
NO other mod.

- Waaaay quieter shot cycle
- Increased Efficiency
- reduced MV

Done in conjunction with mild porting, and modest valve tweaking; you can get back ~all of the MV, and just bask in the satisfaction of the greatly reduced report, and fairly significant increase to shot count.

Great mod, IMHO.

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PostPosted: Sat Aug 08, 2015 5:59 am 
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I am a litlle confused...(not hard),first off, I thought the 2240 "wastes" CO2,especially with the shorter 7-3/4" barrel,mainly by opening the valve too much,so if the lighter hammer or spring was used,would it not (hammer) hit the valve as hard,thus not opening the valve as, much,thus not wasting CO2,thus increasing velocity?
Seems to be more than the 'bigger is better" theory,which I usually subscribe to,as far as the mechanics of the 2240 go. Thanks, Huck

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PostPosted: Sat Aug 08, 2015 10:12 am 
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Yes, the valve is open too long, with the 7 3/4" barrel until after the pellet has left the muzzle, thus it wastes CO2.... However, how can saving CO2 increase the velocity, when said pellet has already left the muzzle?.... It can't.... At best you can only maintain the velocity when you reduce the hammer strike.... If you go to far, the velocity will drop....

As I said in my very first post on this subject, the only way to increase the velocity is to enlarge the ports to increase the volume of CO2 that reaches the pellet while it is still in the barrel.... effectively increasing the pressure at the base of the pellet during the critical first portion of the shot when most of the acceleration takes place.... Therefore the first step is to increase the velocity through improving flow.... Once that is achieved, then you want to close the valve sooner, so as not to waste CO2 after Elvis has left the building....

Bob

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Airsonal;
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PostPosted: Sat Aug 08, 2015 11:07 am 
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Huck wrote:
... would it not (hammer) hit the valve as hard, thus not opening the valve as, much,thus not wasting CO2, thus increasing velocity?

Imagine hitting your hand with a 3 pound hammer. Broken bones, lots of pain, right? Now imagine hitting your hand with a 1.5 pound hammer using exactly the same force (same spring, same spring preload). Maybe broken bones, and sure, it'd hurt... but not nearly so bad as with the heavier hammer, right? So how would a lighter hammer hit with the same force? Is this the new physics they're teaching or something? The reduction in wasted CO2 is not due to a lighter hammer somehow magically using all the same amount of dumped CO2 more efficiently. The barrel length along with the particular pellet's resistance to initial movement (a heavier and/or larger diameter pellet will be more efficient in the same length of barrel) determines the total volume of gas which can be usefully applied to the shot. The reduced waste is due to reduced volume of CO2 being dumped during a less forceful hammer strike on the valve stem. The valve is able to slam shut more quickly thanks to the lesser mass of the hammer, which the remaining pressure can push back more easily.


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PostPosted: Mon Aug 10, 2015 6:51 pm 
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rsterne wrote:
No, making the hammer longer will open the valve less than it does now.... This is because the hammer cocks through a shorter distance, and hence has less stored energy and momentum when it hits the stem.... It does have increased preload (the result of a strange design quirk), but the net effect is that when you extend the nose of the hammer the valve opens LESS not more....

Bob

Thanks!
So how should I go about checking where I need to be regarding some extra feet per second when using this adjustable 1701-P hammer...should I start off with the threaded striker all the way screwed in and then take a few shots over the chrony and keep backing out the striker,one turn at a time and chronying each turn out?
I also have a slightly modded valve,bought from one of the vendors...now which should I install first...the adjustable hammer with the "stock" untouched valve,or install both together?
I also have RVA coming which will allow me to change out hammer springs without taking the back of the gun apart. Which should I change out and in what order?Thanks,Huck

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PostPosted: Mon Aug 10, 2015 7:34 pm 
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I thought I had explained this pretty carefully.... ANYTHING you do to reduce the hammer strike (reduce the weight, travel, or spring) will NOT increase the velocity, it will either stay the same or decrease.... All of those things are intended to save CO2....

To increase the velocity, you have to increase the flow of CO2 from the valve to the pellet, which is done by increasing the port size.... so that means installing a modded valve, or modding the one you have....

Bob

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Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Mon Aug 10, 2015 7:54 pm 
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rsterne wrote:
I thought I had explained this pretty carefully.... ANYTHING you do to reduce the hammer strike (reduce the weight, travel, or spring) will NOT increase the velocity, it will either stay the same or decrease.... All of those things are intended to save CO2....

To increase the velocity, you have to increase the flow of CO2 from the valve to the pellet, which is done by increasing the port size.... so that means installing a modded valve, or modding the one you have....

Bob


So,if the 'stock' 2240 with the 7-3/4" barrel is "wasting" CO2,due to the valve being opened too far and then installing an adjustable hammer and lengthen it,thus not allowing the valve to open as much...so as not to be wasting CO2,would that be saving CO2 or upping the velocity some? Thanks,Huck

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PostPosted: Mon Aug 10, 2015 8:41 pm 
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Huck, I'm afraid I must give up.... You keep asking the same questions, and I keep answering them in the same manner, trying to explain, but it's not working.... I have run out of different ways to say the same thing.... All the answers to your questions are in this thread, several times over.... I apologize that I can't make them any clearer.... Good luck with your build.... Experience will be the best teacher....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Mon Aug 10, 2015 9:00 pm 
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topic39453-15.html

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PostPosted: Mon Aug 10, 2015 9:27 pm 
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While it is becoming tempting to suggest that Huck is trolling with these endless circular questions, I suspect it is more a matter of lacking confidence. None of the changes you have available to you is irrevocable Huck. Throw all the new stuff in there and run some tests at whatever settings you like. Record what you have done and the resulting velocity and shot count per CO2 bulb. Try a lot of things. Learn from experience, as Bob said in his ever so patient last post in this thread. From your collected data figure out what settings you prefer and set the gun like that and get back to shooting it.


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PostPosted: Tue Aug 11, 2015 6:11 am 
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Thanks!...I understand. Huck

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