What method do you use to tune your PCP? I've watched numerous You Tube Videos on tuning and get different results when I use them. Do you start with the Hammer all the way in (CW), or all the way out (CCW) ?
N/A Tuning a Regulated PCP
- Thread starter Freddy J
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You usually want to start with the hammer out/loose and go in until you don't see a benefit anymore to tightening it, knowing the exact gun you're talking about would be helpful but in general thats the way to do it.
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I don't think it matters, but you have to know when the hammer is at maximum effectiveness. That way you know what the speed is when the hammer is letting all the air out of the plenum.
My scheme:
1. Set the reg to somewhere close.
2. Adjust the hammer until the speed is at max. That might require a little hunting back and forth with the hammer spring.
3. If the max speed is around 3-5% above your target speed, back out the hammer spring until the speed is at your target speed. Done.
4. If that is too high or too low, adjust the regulator appropriately and go to step 2.
NOTE: some guns require you to depressurize the gun before lowering regulator pressure. So I recommend you set the reg low on purpose at the start.
I have yet to deal with fancier PCPs like an Impact, where you have two regulators.
My scheme:
1. Set the reg to somewhere close.
2. Adjust the hammer until the speed is at max. That might require a little hunting back and forth with the hammer spring.
3. If the max speed is around 3-5% above your target speed, back out the hammer spring until the speed is at your target speed. Done.
4. If that is too high or too low, adjust the regulator appropriately and go to step 2.
NOTE: some guns require you to depressurize the gun before lowering regulator pressure. So I recommend you set the reg low on purpose at the start.
I have yet to deal with fancier PCPs like an Impact, where you have two regulators.
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Either way will work in most cases. The initial goal is just to find the amount of hammer spring tension necessary to reach the velocity plateau (max velocity achievable with the current regulator setpoint).
However in some cases you can get confusing behavior when starting with maximum hammer spring tension. What happens is the hammer overdrives the valve stem and strikes the valve body, causing it to rebound. The result being unexpectedly low velocity because of very short dwell. So the more certain approach is to start at low hammer spring tension and begin dialing in more.
However in some cases you can get confusing behavior when starting with maximum hammer spring tension. What happens is the hammer overdrives the valve stem and strikes the valve body, causing it to rebound. The result being unexpectedly low velocity because of very short dwell. So the more certain approach is to start at low hammer spring tension and begin dialing in more.
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Whether making tuning adjustments or sighting in a scope.. I always take at least 3 shots between adjustments.
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Hi Freddy J. Look at it from this perspective. If you wanted to destroy your valve assembly as quickly and efficiently as possible, you would bleed all the air out of the gun, then max out the hammer spring compression, then cock the gun and pull the trigger. The valve assembly slams into a metal wall (end-of-travel) and bounces back -- possibly damaged.
I can't type much more since my hand is recovering from minor surgery. Before I quit for today, I do want to emphasize that a lot of people want to quickly try to tune their PCP rifles to maximum power. They do that by maxing out the hammer with a low(ish) plenum pressure. They watch their chronograph readings increase as they, shot by shot, increase the plenum pressure. So they are overdriving their valve until the plenum pressure is enough to no longer be overdriving the valve and the chronograph reading has leveled out and then maybe dropped a little -- that's when they call it good. Trust your gut -- not YouTube videos. For that matter don't trust me either. I see overdriving a valve as bad -- a tiny bit is necessary in order to know you've reached the maximum muzzle velocity. Start with a reasonable plenum pressure (maybe something a bit less than what someone else ended up being happy with -- hard to say where to start), but definitely start adjusting the hammer spring compression from a small amount of compression and increase it by small increments and watch your plenum pressure gauge and chrony. It's medication time. Cheers.
stovepipe
P.S. I forgot to mention that if you start tuning with the hammer spring compression maxed out and you have a particularly strong spring, you might find that your regulator pressure will never be high enough to not be overdriving the valve. Your muzzle velocities will be all over the place -- not good. I know I'm repeating a lot of what's already been said by other folks, but it's coming from my own experience.
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It's a function of where you are and where you want to go. I think most of us, me included, get to fascinated with trying to make the highest fpe possible from a gun. The difference between getting a reasonable weight pellet up to an accurate speed and sending the heaviest pellet you can find to the maximum speed possible is not likely to be worth the trip.
I almost always start with the as-received tune. I say almost because when I got my Avenger they were sending them out with the regulator at maximum and I knew I did not want that. So I dropped it to minimum and worked my way up. That is a totally reasonable thing to do with a gun like the Avenger that allows you to increase the regulator but not reduce it with air in the gun. If you drop the regulator you also need to drop the hammer spring and find the point where you get maximum velocity for that regulator setting then reduce a little for effiency while checking accuracy. But if the maximum you get with that regulator setting is not enough you increase the regulator and try again.
I don't usually increase the hammer spring before I start shooting after I've increased the regulator. I turn it up some during the first few shots looking for the maximum velocity.
I almost always start with the as-received tune. I say almost because when I got my Avenger they were sending them out with the regulator at maximum and I knew I did not want that. So I dropped it to minimum and worked my way up. That is a totally reasonable thing to do with a gun like the Avenger that allows you to increase the regulator but not reduce it with air in the gun. If you drop the regulator you also need to drop the hammer spring and find the point where you get maximum velocity for that regulator setting then reduce a little for effiency while checking accuracy. But if the maximum you get with that regulator setting is not enough you increase the regulator and try again.
I don't usually increase the hammer spring before I start shooting after I've increased the regulator. I turn it up some during the first few shots looking for the maximum velocity.
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For maximum air efficiency, you want a balanced tune. Reg pressure is critical, and if you tune so that the maximum velocity at a given reg setting is 5-10% over your target velocity, then back off the HST a little for your goal, you'll be close. It's a trial and error process, and can be tedious and time consuming. Some folks will say that you need a reg gauge, but I disagree, assuming you are starting from scratch with a new rifle. A gauge allows you to set the reg at a specific pressure, but you don't know that pressure when beginning with no history. The process will take you to the answer.
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