Question is.. If I lower the regulator pressure down to achieve the 900 fps I want, would I gain anything? Increase shot count or lower the es?
Lower regulator pressure for longer shot string ?
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Without changing anything else, maybe a few more shots but not many. Depending on how low you take it you can back off the hammer spring as well. At lower pressures the valve doesn't need to be struck as hard to supply the same volume of air. So the tension on the hammer needed to open the valve at 160 bar isn't needed at 120bar.
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You are asking a real tuner question. As others have said, as you reduce regulated pressure, your hammer strike needs to reduce because it has to overcome less resistance behind the valve (less pressure behind the valve). You will usually get less velocity from your pellet as you reduce pressure. Normally reducing pressure "can" give you more shots, unless you have to increase hammer strike so much that your valve dwell (the amount of time the valve remains open) is excessive to get the desired velocity. If you have too much dwell, then the valve remains open too long, and extra air escapes the end of the barrel *after* the pellet has already left the barrel. This is known as "wasted air". It kills overall efficiency and can result in a lower shot count.
The magic in a lot of tuning is knowing what regulated pressure is the most efficient (once you consider your valve time and ideal dwell time) to achieve your desired velocity (for a given pellet weight). If all things are equal, a heavier pellet typically requires more pressure to achieve the same velocity as a lighter pellet; but it will also have a higher amount of total foot pounds of energy (FPE).
As an example on my Marauder, I have about 1800 PSI regulated pressure which supports an "efficient" 42 shots of 40 FPE with 25.39 grain pellets. I am wanting to go to a heavier pellet, and keep about the same velocity. I will likely have to go up to about 2100 PSI to hit my 50 FPE goal with the heavier pellet. The opposite is true if I was going to a lighter pellet, and wanted to keep its velocity in the stable speed zone. Too fast on a pellet can harm accuracy... most pellets have an ideal sweet spot for velocity versus accuracy.
Enjoy your learning, and of course look for posts where others have done similar things; there is a lot of knowledge in this forum... but sometimes you have to dig.
The magic in a lot of tuning is knowing what regulated pressure is the most efficient (once you consider your valve time and ideal dwell time) to achieve your desired velocity (for a given pellet weight). If all things are equal, a heavier pellet typically requires more pressure to achieve the same velocity as a lighter pellet; but it will also have a higher amount of total foot pounds of energy (FPE).
As an example on my Marauder, I have about 1800 PSI regulated pressure which supports an "efficient" 42 shots of 40 FPE with 25.39 grain pellets. I am wanting to go to a heavier pellet, and keep about the same velocity. I will likely have to go up to about 2100 PSI to hit my 50 FPE goal with the heavier pellet. The opposite is true if I was going to a lighter pellet, and wanted to keep its velocity in the stable speed zone. Too fast on a pellet can harm accuracy... most pellets have an ideal sweet spot for velocity versus accuracy.
Enjoy your learning, and of course look for posts where others have done similar things; there is a lot of knowledge in this forum... but sometimes you have to dig.
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It seems reasonable to assume that a simple chart (to serve as a guide line not a gospel) could be created.
Each caliber may have different behavior characteristics but a chart indicating a reg pressure for pellet weight relationship could be shown.
We could all benefit from that...perhaps a more technical/mathematical AGN member could put this together even as a sticky post.
On the other hand this may be some of that mysterious forbidden knowledge that the airgun tribal shamen guard....but can be had for a price.
Each caliber may have different behavior characteristics but a chart indicating a reg pressure for pellet weight relationship could be shown.
We could all benefit from that...perhaps a more technical/mathematical AGN member could put this together even as a sticky post.
On the other hand this may be some of that mysterious forbidden knowledge that the airgun tribal shamen guard....but can be had for a price.
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First off? What type of gun are you talking about? What cal?
Like addertooth stated there are more factors that need to be considered.
Hammer spring tension, type of hammer system, and regulator pressure plays a role. They all work together.
But in general yes if you reduce the air consumption it will yield more shots.
Like addertooth stated there are more factors that need to be considered.
Hammer spring tension, type of hammer system, and regulator pressure plays a role. They all work together.
But in general yes if you reduce the air consumption it will yield more shots.
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.177 Gauntlet with a JSA tuning kit and their shortened valve spacer(the spacer that the valve stem goes through between it and the hammer).. Wanting to tune to heavier pellet above 10.5 grain. The kit has a adjustable hammer spring tensioner... Just wanting to know once the best heavy is found, would it be better to drop the regulator pressure to the speed I want with the hammer spring tensioner backed out...
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Ah? I think I understand what you're trying to do?
You want to lower the regulator to match the velocity, to the point that there is no jump in FPS when it gets off the regulator.
Then YES! You can gain a bit more shots. But it depends on how many shots you are getting(or wasting) off reg.
Ideally that would be the optimum setting of the regulator if that is where you plan to leave it rifle settings.
You want to lower the regulator to match the velocity, to the point that there is no jump in FPS when it gets off the regulator.
Then YES! You can gain a bit more shots. But it depends on how many shots you are getting(or wasting) off reg.
Ideally that would be the optimum setting of the regulator if that is where you plan to leave it rifle settings.
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10X,
There are way too many variables for a chart. If I made a chart of an unmodified Marauder, it would look nothing like the chart for a modified Marauder. Most Marauders will not dish out 40 FPE at 1800 PSI, but a modified one will. But I do actually like the way you think. Unfortunately, it isn't as simple as it would appear.
There are way too many variables for a chart. If I made a chart of an unmodified Marauder, it would look nothing like the chart for a modified Marauder. Most Marauders will not dish out 40 FPE at 1800 PSI, but a modified one will. But I do actually like the way you think. Unfortunately, it isn't as simple as it would appear.
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Tuning is all a balancing act. For the Gauntlet, does it allow modifying the transfer port?
If you lower the reg pressure, in theory you should achieve a longer shot string, with reduced speed. Less energy imparted to each pellet should give a couple more shots, though I wouldn't expect many more shots.
The reason I ask about the transfer port is for fine tuning. If perhaps you get the reg down to 875, and just can't adjust to 900 for some reason, the transfer port adjustment might be a way to get the speed up or down from where you are.
Tinkering to improve is so much fun!
If you lower the reg pressure, in theory you should achieve a longer shot string, with reduced speed. Less energy imparted to each pellet should give a couple more shots, though I wouldn't expect many more shots.
The reason I ask about the transfer port is for fine tuning. If perhaps you get the reg down to 875, and just can't adjust to 900 for some reason, the transfer port adjustment might be a way to get the speed up or down from where you are.
Tinkering to improve is so much fun!
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addertooth
There are plenty of variables....seemingly innumerable settings of reg, of HST, pellet weight, size, fit, transfer port size etc...like most of us airgun affectionados/tinkerers, I observe trends and of course FX has accommodated us somewhat by selling us adjustability (relatively easy adjustability) with the purpose of manipulating what matters to get a performance level ei; efficient shot count at the desired fpe....
After your comment I thought of the emense undertaking to chart out the necessary amount of data to have usable charts for various combinations and calibers and the settings and variations....
In the end if I get 60 regulated shots from my 22 Royale instead of say, the possible better setting to get 70 shots I'm ok with that..
There are plenty of variables....seemingly innumerable settings of reg, of HST, pellet weight, size, fit, transfer port size etc...like most of us airgun affectionados/tinkerers, I observe trends and of course FX has accommodated us somewhat by selling us adjustability (relatively easy adjustability) with the purpose of manipulating what matters to get a performance level ei; efficient shot count at the desired fpe....
After your comment I thought of the emense undertaking to chart out the necessary amount of data to have usable charts for various combinations and calibers and the settings and variations....
In the end if I get 60 regulated shots from my 22 Royale instead of say, the possible better setting to get 70 shots I'm ok with that..
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10X what is the caliber and tank volume of your FX... knowing these two things I can guess whether you can theoretically hit 60 shots. As a reference, I get forty-two regulated shots (fastest shot in the string versus slowest shot in the string 1.8 percent variation). It gives 40 foot pounds of energy with each shot with 25.39 grain .25 caliber JSB ammo. My air tube volume is about 190cc. If you are the same caliber, and are satisfied with 40FPE, and your tube volume is 300cc or more, it should be very achievable if your FX has been optimized.
Your FPE will have to be lower (due to the smaller caliber) in order to achieve the same efficiency.
I just checked, the FX Royale 400 series .22 caliber air rifles have a 400cc tank. So other than not being the same FPE, 60 shots should be VERY achievable...
This guy got a 100 shot string with a 400cc tank and regulated. His target was 900 FPS with a 18.13 grain pellet, 33FPE.
http://www.airgunsforum.com/showthread.php?p=907
Your FPE will have to be lower (due to the smaller caliber) in order to achieve the same efficiency.
I just checked, the FX Royale 400 series .22 caliber air rifles have a 400cc tank. So other than not being the same FPE, 60 shots should be VERY achievable...
This guy got a 100 shot string with a 400cc tank and regulated. His target was 900 FPS with a 18.13 grain pellet, 33FPE.
http://www.airgunsforum.com/showthread.php?p=907
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A huge factor of wasted air and shot count is Hammer bounce! Manufactures like FX and Daystate figured this out. I'm not sure if Umarex has gotten there yet?
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In a Gauntlet .177 I am getting 890fps w10.9g JSB factory stock, no idea of shot count as I use only the single shot tray and havent shot a fill in one sitting yet, guess I should. My reg is verified at 1,100psi ( +/- 40fps , best the gauge claims ).
From the sound it is easy to learn it IS burping or "bouncing" . Just for efficiency I keep meaning to try drop a felt washer over the valve stem - like a QB-. Only as it's the fastest lowest cost and often works, soft of a b-staley thang-. The hammer/striker is TOO heavy , if wanting efficiency perhaps lighten that, it is also way over sprung . You can use a light striker and lighter spring and keep your stock number but increase count tho that bounce is still the wasted air- I believe.
Summers coming I may play with modding thisone but for power/slug as it can take a .177 pellet about 1/2" in length. But wont want to mess with my seemingly Golden barrel.
Good value rigs no matter your end goal. There may be some competition for the Gauntelt coming down the road but until they are proven ( and actually available) under $1,000 for 1st time buyer's it's the one I hand them to try first.
John
From the sound it is easy to learn it IS burping or "bouncing" . Just for efficiency I keep meaning to try drop a felt washer over the valve stem - like a QB-. Only as it's the fastest lowest cost and often works, soft of a b-staley thang-. The hammer/striker is TOO heavy , if wanting efficiency perhaps lighten that, it is also way over sprung . You can use a light striker and lighter spring and keep your stock number but increase count tho that bounce is still the wasted air- I believe.
Summers coming I may play with modding thisone but for power/slug as it can take a .177 pellet about 1/2" in length. But wont want to mess with my seemingly Golden barrel.
Good value rigs no matter your end goal. There may be some competition for the Gauntelt coming down the road but until they are proven ( and actually available) under $1,000 for 1st time buyer's it's the one I hand them to try first.
John
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Addertooth
You sound like you know a lot about this...
Yes my Royale is .22 with a 400 cc bottle (an oldie without a power adjustment wheel or reg)....I installed a HUMA reg (set at 150 per marks on reg) after drilling a breather hole. I then shot 18.1 JSBs over the chrony screwing in the HST screw until the velocity reached 880fps....locktite goo and now I shoot 5 twelve shot magazines down to 150bar before I refill the air bottle to 220 bar.....
From my reading here and my experience with this Royale and several other PCPs... I am close to peak efficiency and shot count...
As an observation, the higher the FPE the amount of wasted air to achieve high FPE goes up steeply.
You sound like you know a lot about this...
Yes my Royale is .22 with a 400 cc bottle (an oldie without a power adjustment wheel or reg)....I installed a HUMA reg (set at 150 per marks on reg) after drilling a breather hole. I then shot 18.1 JSBs over the chrony screwing in the HST screw until the velocity reached 880fps....locktite goo and now I shoot 5 twelve shot magazines down to 150bar before I refill the air bottle to 220 bar.....
From my reading here and my experience with this Royale and several other PCPs... I am close to peak efficiency and shot count...
As an observation, the higher the FPE the amount of wasted air to achieve high FPE goes up steeply.
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10X, your observation is spot on. For the record, on my Marauder the Huma regulator is set to 1800 PSI, or effectively 122 bars (according to the marks on the regulator, actually 115 Bar but it has an error in it's markings on mine). All air rifles have a sweet spot where they get good air efficiency, if you exceed that energy/velocity, then overall efficiency suffers. Increasing porting, and improving flow tends to raise the sweet spot up. I suspect the sweet spot for my marauder is in the 40 to 50 FPE range (depending upon the weight and type of pellet), but my Maximus has a much lower sweet spot. I am not sure a Bulldog could be tuned down to reliably and repeatedly do 50 FPE. Your ears will tell you a lot. Most air rifles tend to be quieter when they are operating in their sweet spot. Once they start getting louder, you are pushing some limit in the design. Some people don't even try to hit the best efficiency FPS/FPE, they instead focus on what power level gives the smallest fast shot to slow shot variation in a string. My rule of thumb is to try to keep under a maximum variation of 2 percent in a string, with less being even better. Once you get beyond that, your point of impact at 50 yards starts to be discernable.
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