Ways to tune a regulated PCP

I'm not a tuner, but, I don't see anything wrong with your logic.

Several guns also have the option to manually adjust the hammer spring tension too so you can basically fine tune to any speed using a combination of that and the regular pressure.

Yup, that's about as simple an explanation you can get. Once you've experimented with each option to it's extent without changing the others to learn how they work the fun part begins. Mixing the different techniques for the best/most consistent velocity, standard deviation and extreme spread for your given round. Did I mention the swearing and hair pulling...................that too.

Yes like John said thats the basic ways to tune a regulated air rifle. The important thing is knowing which needs to be done to get the correct tune. You might need to add hammer energy and leave the reg setting alone or you might need to up the regulator and leave the hammer alone or both might need to be adjusted with one raised and the other lowered or both raised or both lowered. Theres allot more to it than just cranking up the reg setting to gain power or lowering the hammers energy to drop power if you want the most efficient tune.

changing valve springs?
i think that makes no difference.
its a very small spring and the pressure behind is MUCH stronger.
we are talking about 1200 - 4000 psi
the only purpose that this spring has is to close the valve when you cylinder/bottle is completly empty

"Hubertus"changing valve springs?
i think that makes no difference.
its a very small spring and the pressure behind is MUCH stronger.
we are talking about 1200 - 4000 psi
the only purpose that this spring has is to close the valve when you cylinder/bottle is completly empty

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May I ask how many rifles you have regulated and tuned?

The valve spring definitely effects velocity

Common regulated set point of 2000 psi (138 bar) on my .252" OD poppet see's 103 lbs of force against it. If I retained the stock valve spring @ 30 lbs/inch, when installed its likely compressed around .33" which gives 10 lbs extra or close to 10% more force against poppet, or I can use a light spring like I have installed at the rate of 6 lbs/inch when installed its pre-loaded 2 lbs which is only 2% more force. That 8% may not seem like a lot to some but when it translates to 8% less spring energy required you obtain a much easier to cycle rifle, or 8% less hammer weight which can reduce cyclic vibration and lock time.

I run a .252" poppet with .211" porting which allows me to make 60 FPE @ 2000 psi with 33.95 gr pellets on just 7.7 lbs/inch of hammer spring. A heavier valve spring like above would require roughly 8.3 lbs/inch of hammer spring or at least 8% more pre-load of the current 7.7 lb spring if it were available...so if I have .5" preload with .8" travel my final cocking force on the 7.7lb spring is 10 lbs. With the heavier valve spring and more preload the final cocking force would be closer to 11 (10.8).

In regulated applications the statement "valve spring's primary duty is to keep valve closed when filling gun from empty" is mostly true. Its best to look elsewhere for velocity increase/decrease primarily because its best to just have the lightest spring installed that performs its primary function in regulated guns. Non-regulated tuning on the other hand, the rifles bell curve is quite heavily dependent on the valve springs ability to offset the difference in force against the poppet through out the pressure range of the rifles shot string.

-Matt

mmahoney once you start the new thread for your specific tune I will throw some info in there that will get you headed in the right direction unless someone else with some experience beats me to it When you start that thread make sure to include the current reg setting and velocity and what you want to accomplish so we can be more direct with the help.

Yup, that's about as simple an explanation you can get. Once you've experimented with each option to it's extent without changing the others to learn how they work the fun part begins. Mixing the different techniques for the best/most consistent velocity, standard deviation and extreme spread for your given round. Did I mention the swearing and hair pulling...................that too.

Click to expand...

LMAO at the ending

I've heard (so this is worth what you paid for it) that on guns like a Marauder with an transfer port adjustment screw, set the reg at the desired pressure, open all other adjustments, except the transfer port, then adjust the transfer port to achieve final velocity. This might require removing the reg from the gun and adjusting several times to get the right pressure, but once set, it's set.

That would be about the same as the Impact adjustments, if you draw the parallel. Adjust the reg pressure close to desired velocity, adjust the valve screw to finalize velocity, then you can use the power wheel to slow the pellet down for different kinds of shooting. So far I haven't found much use for the power wheel.

Oh, and on the Marauder field and target model, firing 14.3 grain Premier Domes, the reg pressure seems (at least in the review videos), the reg pressure seems to be set between 1400 and 1500PSI, achieving around 800 fps. Reg pressure depends on what you shoot, and desired velocity

Good luck

on my Prod w/Huma regulator set at 96bars it shoots about 590fps when set at a higher pressure it shoots at a lower fps...at 124bars the valve barely opens up. Basically too high reg pressure reduces the valve opening. It shoots fastest fps at 96bars, higher bar reduces fps. The hammer spring is too soft and can't push against the higher pressure. I'm thinking of getting a softer valve spring because the heavier hammer spring makes it harder to slide the bolt back.

DaBinChe have you tried to swap out transfer ports yet? I think expermenting with different size TPs will solve your problems.



CA

If you want (and have time) to watch a seriously excellent video about what one owner did to tune a rifle by adding a regulator check out the video link below. 

The second link is a post that I think is pinned on AGN and is specific to efforts he took to tune his newly regulated rifle...I was very impressed by both his meticulous skills and the degree to which he researched materials and the clarity by which he presents his tune-up.







https://www.youtube.com/watch?v=HQAfyI6qSqA







and 

https://www.airgunnation.com/topic/an-air-odyssey_installing-altaros-regulator-and-short-stroking-an-aas510-extra/

Hello ALL

The ULTIMATE goal here is to find out at what reg pressure your particular gun will shoot the best at.

We are talking about adjusting the reg pressure specifically for accuracy here, not necessarily for power.

If you want to find out what the optimum reg pressure for YOUR gun then you need to tether your UNregulated gun

using an adjustable regulated valve coming from your High pressure tank. OR set your regulator on your regulated

gun at a higher setting than you think you will need then either way use this device-

https://www.airgunnation.com/topic/regulator-suggestions-for-tethered-line-to-airgun/

And after you have found the magic pressure your gun likes you set it at pressure THEN do all of the fine tuning.



CA

I'm looking for some correction if my below understanding is wrong. It is my understanding that: To increase the velocity of the shot string:

• Raise the regulated pressure - This causes the air released from the valve to come out faster and thus push the pellet harder.
• Add weight to the hammer- This causes the valve pin to be hit harder and thus allow more air to escape and push the pellet harder.
• Install a stronger hammer spring- This causes the hammer to hit the valve pin harder and thus allow more air to escape.
• Install a weaker valve spring- This makes the valve easier to open so that more air escapes when the valve pin is hit.
• Open the transfer port wider- This allows more air flow to push the pellet.

To decrease the velocity of the shot string:

• Lower the regulated pressure- Air pushing pellet has less presure so pushes it at lower velocity.
• Remove weight from the hammer- Causes hammer to hit valve pin softer so less air escapes.
• Install a weaker hammer spring- Causes hammer to hit valve pin softer so less air escapes.
• Install a stronger valve spring- Causes valve to be harder to open and quicker to close causing less air to escape.
• Reduce the size of the transfer port- allows less air available to push the pellet.

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I agree , I only sequenced and noticed it in according of my point of view :

1. Open the transfer port wider - This allows more air flow at the same poppet dwell/time . Cut also some edges on all transfer way.
2. Raise the regulated pressure – This may causes raise the acting force in to the pellet.
3.  To enable it you need to use stronger hammer spring or some spring preloading . Higher air pressure need more valve cracking force .
4. You may also add hammer weight a little bit .This causes the valve to stay open longer time - more dwell , because higher weight hammer brake returning of the poppet . Too heavy hammer may cause loudness and inefficiency especially with the short barrel.
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   Easiest and best way .to reduce the power is to choke the air transfer way.
   
   Adding/threading some choking screw with some press seal under the screw cup is easy too. Easiest way is therefore to use screw with different lengths for each power.
   
   

DaBinChe have you tried to swap out transfer ports yet? I think expermenting with different size TPs will solve your problems.



CA

Click to expand...

I have the largest transfer port from Hill airguns also their valve kit too and a MM/WAR hammer forge barrel so all the air passageways are as open as they can be. As I said it is just a matter of the pressure being too high for the hammer spring and weight to open the valve enough....but don't want a heavier then stock hammer spring because as is it is hard to cock, think a softer valve spring would be best or a heavier hammer but that option is not available.

Going to try this weekend see what numbers I get