Tuning my new P-rod

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fishinwrench

fishinwrench

Member
Nov 25, 2017
589
16
mo
I'm a bit confused because every review and tuning video says the best pressure is about 2600 to 1500, but mine (totally stock) does best from 3000 to 1400 with a tune of 6 turns spring/ 2 turns throw. That's 21-23 shots. And the hands down best grouping pellet is Predator Poly Mag's 16gr. followed closely by CPHP 14.3's, and JSB 18.1's coming in at a close 3rd.

I'm not tuning with a chrony though, I am going only by the ability to keep every shot within a 1.5" circle at 30 yards. In other words..."minute of squirrel head".

I ordered a .105 TP and a heavier hammer spring from Hill, assuming that I was gonna want more power, but now I'm questioning whether or not I even need/want to do the performance mod.

By going forward with the bigger TP and stronger spring what do you think my losses and gains will amount to ? I just don't wanna end up wishing I'd left well enough alone.

Thanks for listening/reading. 🤔


 
Dear Wretch...

I reamed out several ports in the Prod, used a heavier spring, and although your shot count will likely go down a bit, you might find a heavier pellet will do better with accuracy. I was shooting 21 gr JSB's and had no accuracy problems. You can always dial the hammer spring back if too much power becomes a problem...unlikely, but anything is possible.

I ended up shooting slugs, because that Prod can be brought up to short carbine performance. It's a "sleeper"...do a little reading on Prod performance. You might end up putting a buttstock on it.



Regards,

Kindly 'Ol Uncle 
 
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trying to tune a PCP without a chronograph is like running in circles. A chrono is about the same cost as 5 tins of pellets. That 1.5" circle isn't going to tell you what that larger TP and hammer spring did. To get the most out of your gun, it may involve just the slightest tweaks on that hammer spring. Only a chronograph, and being able to look at your shot strings will enable you to do this.
 
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Check out this little chrony, brought to our attention by Cyclopse dude... ~35 bucks. That is about the cost of only 6 tins of CPHP from Walmart... Do note that it only measures in METERS per Second. Multiple by 3.208 to get FPS.



https://www.airgunnation.com/topic/compact-budget-chronograph/



Direct link

https://www.aliexpress.com/item/Free-postage-Muzzle-Speed-Meter-Velocimetry-Velocity-Anemometer-Vale-nce-Tester-with-Tripod-CS-muzzle-speedometer/32954736508.html?spm=2114.search0204.3.67.628f387dan9KGr&ws_ab_test=searchweb0_0%2Csearchweb201602_1_10065_10068_10130_10890_10547_10546_319_5734911_10548_317_5730311_10545_10696_10924_453_10084_454_10083_5729211_10618_10920_10921_10922_10307_537_536_5735011_10059_10884_5735111_10887_10928_100031_321_322_10103_5735211%2Csearchweb201603_51%2CppcSwitch_0_ppcChannel&algo_pvid=f2e0ac21-b806-43fe-82e2-075ceb4efd94&algo_expid=f2e0ac21-b806-43fe-82e2-075ceb4efd94-11
 
Upvote 0
trying to tune a PCP without a chronograph is like running in circles. A chrono is about the same cost as 5 tins of pellets. That 1.5" circle isn't going to tell you what that larger TP and hammer spring did. To get the most out of your gun, it may involve just the slightest tweaks on that hammer spring. Only a chronograph, and being able to look at your shot strings will enable you to do this.
Click to expand...



No truer words have been spoken Fish. You'll be glad you got one. You will spend more on pellets chasing your tail without one.
 
Upvote 0
trying to tune a PCP without a chronograph is like running in circles. A chrono is about the same cost as 5 tins of pellets. That 1.5" circle isn't going to tell you what that larger TP and hammer spring did. To get the most out of your gun, it may involve just the slightest tweaks on that hammer spring. Only a chronograph, and being able to look at your shot strings will enable you to do this.
Click to expand...



No truer words have been spoken Fish. You'll be glad you got one. You will spend more on pellets chasing your tail without one.
Click to expand...

+2 on the chrony. If you go past the max FPS (hammer spring) you will start losing power and without a chrony you will never know. 

edit: Mine's doing about 750FPS 19-20 FPE at 16 shots with 18.13 gr JSBs.
 
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Ok (dammit) I'll get one ordered and on the way. It's pretty obvious that I'm gonna never be "sure" until I do.

Appreciate the advise.
1f44d.svg
Click to expand...

I think one of those cheapies would work just fine. You need to see when to stop cranking on the hammer spring. 
 
Upvote 0
Ok (dammit) I'll get one ordered and on the way. It's pretty obvious that I'm gonna never be "sure" until I do.

Appreciate the advise.
1f44d.svg
Click to expand...

I think one of those cheapies would work just fine. You need to see when to stop cranking on the hammer spring.
Click to expand...



I agree. It's ordered and on it's way. 😊



I am not satisfied with my understanding of the hammer stroke adjustment. Let's say for my current spring tension setting of 6 turns....does decreasing hammer stroke length cause the valve to stay open longer even at higher pressures, or is hammer stroke adjustments only beneficial at lower pressures (like under 2000psi) ?
 
Upvote 0
Ok (dammit) I'll get one ordered and on the way. It's pretty obvious that I'm gonna never be "sure" until I do.

Appreciate the advise.
1f44d.svg
Click to expand...

I think one of those cheapies would work just fine. You need to see when to stop cranking on the hammer spring.
Click to expand...



I agree. It's ordered and on it's way.
1f60a.svg




I am not satisfied with my understanding of the hammer stroke adjustment. Let's say for my current spring tension setting of 6 turns....does decreasing hammer stroke length cause the valve to stay open longer even at higher pressures, or is hammer stroke adjustments only beneficial at lower pressures (like under 2000psi) ?

I notice that at higher pressures my gun is extremely quiet until it gets down to about 2300psi, then she starts to bark considerably louder.....but POI does not change much( if at all). Can I tweak that change in bark by slight adjustment in hammer throw ?
Click to expand...


 
Upvote 0
Ok (dammit) I'll get one ordered and on the way. It's pretty obvious that I'm gonna never be "sure" until I do.

Appreciate the advise.
1f44d.svg
Click to expand...

I think one of those cheapies would work just fine. You need to see when to stop cranking on the hammer spring.
Click to expand...



I agree. It's ordered and on it's way.
1f60a.svg




I am not satisfied with my understanding of the hammer stroke adjustment. Let's say for my current spring tension setting of 6 turns....does decreasing hammer stroke length cause the valve to stay open longer even at higher pressures, or is hammer stroke adjustments only beneficial at lower pressures (like under 2000psi) ?

I notice that at higher pressures my gun is extremely quiet until it gets down to about 2300psi, then she starts to bark considerably louder.....but POI does not change much( if at all). Can I tweak that change in bark by slight adjustment in hammer throw ?



Is that change in "bark"thee "double bounce" that I keep hearing about?

Click to expand...

Click to expand...


 
Upvote 0
Ok (dammit) I'll get one ordered and on the way. It's pretty obvious that I'm gonna never be "sure" until I do.

Appreciate the advise.
1f44d.svg
Click to expand...

I think one of those cheapies would work just fine. You need to see when to stop cranking on the hammer spring.
Click to expand...



I agree. It's ordered and on it's way.
1f60a.svg




I am not satisfied with my understanding of the hammer stroke adjustment. Let's say for my current spring tension setting of 6 turns....does decreasing hammer stroke length cause the valve to stay open longer even at higher pressures, or is hammer stroke adjustments only beneficial at lower pressures (like under 2000psi) ?

I notice that at higher pressures my gun is extremely quiet until it gets down to about 2300psi, then she starts to bark considerably louder.....but POI does not change much( if at all). Can I tweak that change in bark by slight adjustment in hammer throw ?



Is that change in "bark"thee "double bounce" that I keep hearing about?

Click to expand...

Click to expand...

Click to expand...

My P-rod has a loud bark but you can tune down some. For the hammer throw adjustment is to find the peak FPS and then back it off a little. Now for the hammer bounce you can install 2 or 3 o-rings inside up against the valve to keep the hammer from knocking open the valve again causing wasted air. Find an o-ring that is the same size as the ID where the hammer goes. Hill airgun sells all the parts you need. LINK....https://hillairgun.com/
 
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There are so many directions you can go with a Prod. Without putting a regulator in it, you can go from a one magazine wonder cannnon to a 5 magazine target gun. I personally like a 3 magazine gun with decent power. Three mags is easy to remember for refilling the gun and more than 20 shots is a nice shooting session. Your not constantly running to the pump. If I want to shoot 18gr pellets over 800fps, I have other guns that do that without breaking a sweat. There is a standard gun best tune out there. There are videos and I am sure guys have posted it on forums. I used it for a while. YouTube “Tuning Maurader pistol” is like 7 turns on the spring, 1 turn out on the hammer throw. It’s a good tune, almost 700fps with a 14.3gr pellet. I think the fill pressure is 2,800. Which brings me to the last thing. If you watch the video n2stuff posted a link to, that guy in the videos fill pressure is too high. He is wasting effort and shots until his gun gets in the sweet spot. Lots to learn. I have a box of big springs and giant transfer ports that were a waste of money. I use a 140 TP, SS valve and my own SSG and spring for 765-785fps for 20 shots. I got tired of messing with it but I hope to get a 750fps for 24 shot tune when I feel like messing with the gun again.
 
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Ok well of course I now have an issue. Installed a WAR moderator and after a bit my groups went to hell. Thought it was the moderator but removed it and the groups didn't tighten up. Cleaned the barrel....no help. Checked my tune and noticed that hammer throw setting had moved. Reset it and it shot good for about 2 magazines then the throw setting moved again (it turns too easily IMO). So now I have the throw backed off fully CCW since it seems to hold that setting ok.

So what do I need to do to make it where it will hold my hammer throw settings ? A little blue loc-tite maybe ?

By having the throw completely backed off my sweet spot psi is now considerably lower and shorter (down around 2200-1700) which I don't care much for.
 
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