N/A How to determine FPS

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Depends on the projectile. Often you can search on here or other forums and find a good idea of what a particular projectile likes. Of course this is just a baseline and some trial and error will ensue as every gun is a little different. Pellets are much easier than slugs. If you hit anywhere between 850-920 you are often good.
 
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Trucker3573 said:
Depends on the projectile. Often you can search on here or other forums and find a good idea of what a particular projectile likes. Of course this is just a baseline and some trial and error will ensue as every gun is a little different. Pellets are much easier than slugs. If you hit anywhere between 850-920 you are often good.
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In the video, his FPS range was only 5 FPS. It appears more complicated than you suggest. I'm wondering if there's a pickoff chart of pellet weight versus best FPS.
 
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Plinkalot said:
I just watched this tuning video which I found to be the best so far for tuning an FX Impact.

However, he doesn't explain how he determined the original FPS he was trying to achieve.

So how do you pick a starting FPS to tune to?

Thanks
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you need a chronograph to measure FPS, then input that FPS and the pellet weight and voila you can have FPE.
 
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Plinkalot said:
The gun and barrel length shouldn't matter to my original question. I want to use all kinds of different pellets and weights in all kinds of different guns. I'm looking for the starting point of FPS to tune to.
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I’m out. I tried good luck to you I hope you find what you are looking for
 
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Plinkalot said:
What I'm trying to understand is the initial FPS to tune to. If .22 pellets are good for 850-920 FPS where do you start? If 905 is actually best, but I start at 890 and tune to it, how would I know that 890 isn't the best?
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The speed for a given pellet and rifle/barrel that accomplishes the tightest group if accuracy is all that matters. Alternatively the fps that produces the best compromise of group size and shot count or yet another alternative, if a hunter, is the fps that produces the best compromise of power and accuracy.
 
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You really can't know what your target is unless you're tuning for fpe, and you don't care what your accuracy does. It's an experimental determination. You try different velocities and test accuracy while noting power (if power is important to you). When you've fully optimized whatever you're after (velocity or accuracy) or you've find a point that you're satisfied with, you're done. Even two "identical" rifles will likely have optimal tunes that are more than 5 fps apart.

GsT
 
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Plinkalot said:
What I'm trying to understand is the initial FPS to tune to. If .22 pellets are good for 850-920 FPS where do you start? If 905 is actually best, but I start at 890 and tune to it, how would I know that 890 isn't the best?
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Most Diablo pellets fly nicely at aprox 880 fps some destabilize after 930 fps using unnecessary speed (air and hammer force) can waste air and create a harsh shot cycle. Slugs seem to like it much faster 960 fps and up.
you HAVE to experiment with reg pressure, hammer tension AND different pellet types... as every gun may yield slightly diff. results. so there ya go...
sometimes is difficult to know "how to ask a question" in order for people to know how to answer you.
 
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Plinkalot said:
I just watched this tuning video which I found to be the best so far for tuning an FX Impact.

However, he doesn't explain how he determined the original FPS he was trying to achieve.

So how do you pick a starting FPS to tune to?

Thanks
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Hi Plinkalot. I understand your question. When you are new to all of this and you suddenly have a pcp rifle that allows you to change the plenum pressure and how hard the valve is getting hit by the hammer and can also use lots of different weights of pellets and slugs and can also use barrels of different lengths and twist rates and even change calibers -- well, it's like having a portable laboratory.

So when you hear someone say they tune to such and such fps or you watch a youtube vid that says "I'm going to tune for such and such fps", of course you say "Wait a minute -- where the hell did that fps value come from?", and it's good that you are asking.

These fps values come all over the place from guys that have tried lots of (or maybe just a few) different values and say they like it best at value X or in a range from X to Y. It's not like there is a database that I know of. It's tidbits of blurbs spread all over this forum and other forums and youtube vids, etc. In most cases the proclaimed "favorite" tune is incomplete -- fps is specified, but other important info is missing.

If you find and read enough posts that talk about tuning the same rifle as yours shooting the same projectile, then you will get a sense of what's in the ball park as far as fps goes. It's important to note that the same fps can be obtained by changing both the regulator pressure and hammer spring compression and, even though the fps is the same, the resulting accuracy can be wildly different.

stovepipe
 
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stovepipe said:
Hi Plinkalot. I understand your question. When you are new to all of this and you suddenly have a pcp rifle that allows you to change the plenum pressure and how hard the valve is getting hit by the hammer and can also use lots of different weights of pellets and slugs and can also use barrels of different lengths and twist rates and even change calibers -- well, it's like having a portable laboratory.

So when you hear someone say they tune to such and such fps or you watch a youtube vid that says "I'm going to tune for such and such fps", of course you say "Wait a minute -- where the hell did that fps value come from?", and it's good that you are asking.

These fps values come all over the place from guys that have tried lots of (or maybe just a few) different values and say they like it best at value X or in a range from X to Y. It's not like there is a database that I know of. It's tidbits of blurbs spread all over this forum and other forums and youtube vids, etc. In most cases the proclaimed "favorite" tune is incomplete -- fps is specified, but other important info is missing.

If you find and read enough posts that talk about tuning the same rifle as yours shooting the same projectile, then you will get a sense of what's in the ball park as far as fps goes. It's important to note that the same fps can be obtained by changing both the regulator pressure and hammer spring compression and, even though the fps is the same, the resulting accuracy can be wildly different.

stovepipe
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Hey stovepipe,

Thanks for that... makes perfect sense.

What I'm coming to realize (and all of you have been saying) is I can tune to the extremes of either max FPE of max shot count, or anywhere inbetween, for any particular pellet or weight. And I can do this at any particular FPS.

So I could tune for a light pellet for plinking at max shot count and lowest FPS where I get good groups?

I could also tune for a heavy pellet at max FPE and an FPS that gives me good groups?

Can I then switch between these tunes simply be reverting back and forth to the different settings for each tune? Do you guy keep a log of settings/tunes for your favorite pellets and uses?

BTW, my rifle is an FX Impact M4 Sniper .22 cal. It will be here tomorrow. I'm putting an ATN X-Sight 4K scope on top. Expecting to have lot of fun with this rig.
 
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Plinkalot said:
Hey stovepipe,

Thanks for that... makes perfect sense.

What I'm coming to realize (and all of you have been saying) is I can tune to the extremes of either max FPE of max shot count, or anywhere inbetween, for any particular pellet or weight. And I can do this at any particular FPS.

So I could tune for a light pellet for plinking at max shot count and lowest FPS where I get good groups?

I could also tune for a heavy pellet at max FPE and an FPS that gives me good groups?

Can I then switch between these tunes simply be reverting back and forth to the different settings for each tune? Do you guy keep a log of settings/tunes for your favorite pellets and uses?

BTW, my rifle is an FX Impact M4 Sniper .22 cal. It will be here tomorrow. I'm putting an ATN X-Sight 4K scope on top. Expecting to have lot of fun with this rig.
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Absolutely keep a log of your tuning parameters -- projectile used, plenum pressure, hammer spring compression, hammer weight if you use different ones for different tunes, hammer spring used if you use different springs for different tunes, average muzzle velocity, standard deviation of muzzle velocity, shot count of strings put through chronograph, and notes of how well it grouped at what distances, ambient temperature, and anything else you can think of that might be noteworthy. Oddball notes might include such things as "drank way the hell too much coffee before shooting these groups".

The point is that the last tune you TESTED is almost never going to be the tune you end up sticking with. You will try lots of tunes and finally decide that "what I did last tuesday was the best so far". So you check your notes and set things back to the way they were last tuesday.

stovepipe
 
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Plinkalot,
I had a very similar question not too long ago, and with responses and experimentation... there is no absolute answer. The truth??? There will be a big range of velocities for each pellet that will shoot more accurately than you can (assuming, of course, you're not a nationally ranked bench rest guy ;-))

User jakob8572 responded with a very helpful link showing fps/bar/hammer/barrel/pellet relationships for Maverick/Wildcat - even though you are getting an Impact, it should give you some reference points to start with.

chart link
 
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TitanRebel said:
Plinkalot,
I had a very similar question not too long ago, and with responses and experimentation... there is no absolute answer. The truth??? There will be a big range of velocities for each pellet that will shoot more accurately than you can (assuming, of course, you're not a nationally ranked bench rest guy ;-))

User jakob8572 responded with a very helpful link showing fps/bar/hammer/barrel/pellet relationships for Maverick/Wildcat - even though you are getting an Impact, it should give you some reference points to start with.

chart link
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TitanRebel,

Thanks for that. I'm a data nut so this will give me hours of wasted time ;) .

Seriously, this is great stuff for a newbie, thanks.
 
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Plinkalot said:
BTW, my rifle is an FX Impact M4 Sniper .22 cal. It will be here tomorrow. I'm putting an ATN X-Sight 4K scope on top. Expecting to have lot of fun with this rig.
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I strongly suggest that you clean the barrel of your new airgun and then just shoot it with the factory settings. Try pellets in the 15 to 18 g range.

Don't worry about tuning until the airgun is well broken in - at least 500 pellets. Get to know the airgun before messing with it - and record settings and pressures before making any changes.

You have to tune to YOUR gun! Dial settings, internal parts, regulator manometers, chronographs, etc. all have tolerances. Someone else's tune may work ...maybe. OK to use for reference, as a starting point.

Here's a good tuning reference...



Have fun with your new PCP!

Cheers
 
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