Tuning M3 Help Needed

Looks like the .22 Sniper requires a different (harder) valve adjuster spring C51. Ask the dealer if he replaced it.

What dealer did you buy from? If your M3 was a .35cal and they replaced the barrel and then put a dull transfer port then they don't know how to tune a M3 or impact!! They have to change the spring to a lighter one and changes need to be made on a few other items you can't just swap a barrel out. You will never tune your M3 to shoot any less then you have said. Send it back to be tuned professionally. Sorry buddy but it is a awesome airgun once you get it worked out 

Or... you could just turn the reg up  

Contrary to popular belief, a higher reg setting will be more efficient, due to the valve having more pressure behind it. That results in the valve closing faster, and wasting less air. That will also get those power adjustments working better too in your case. The downside of higher reg settings for lower power use can be a bit more ES in some guns. I rarely find it to be enough to matter at most distances people are shooting though(on low power tunes). Most people that are shooting long distance stuff are shooting heavier ammo at higher power, which necessitates a higher reg setting anyway. That is all within reason, of course. I'm not saying set the 2nd reg to 150 bar or anything, but maybe 100-110-ish bar would be the ticket in your case. This is assuming the hammer spring adjustment is on the lower end.

With a too-light spring you are overdriving the valve rod at the higher hammer settings, and it's bottoming out and rebounding so fast that it closes the valve sooner, resulting in less velocity. As you decrease hammer the rebound stops, valve is open longer, and velocity rises. Same thing with too much hammer for the reg pressure, which is what you described in your OP. So yes, get the right spring OR increase the reg--which you will of course do while waiting for the spring anyway.

Marl3y, I have a different take on looking at this situation, but first, I need you to fill your gun tank to capacity and write down the pressure, then start taking shots without valve spring, hammer spring, Macro/micro and write down the tank pressure drop at each shot or group of shots until you get at least 20, or more to make it statistically significant; else, its a WAG. Report back the pellet weight, velocities and pressures, also the tank volume if it is a 300 cc, 400 cc, or 580 cc, and fill pressures either 250 Bar, or 310 Bar.

The best place to start is by setting your valve spring adjuster at the center, the macro at 8, and micro at 3. Then adjust your regulator for your desired velocity. Keep in mind that the best combination of precision accuracy AND power is right below 889 feet per second (fps). Once you go above that you will have more power, but at a loss of precision due to entering transonic turbulent Eddie currents that play havoc on projectiles from spit wads to 747s. The 889 fps is at just below Mach 0.8 at STP, and you don't want to hit that wall. The Mach is taken at station and varies with the speed of sound which is approximately 20 x sqrt (absolute temperature), so each degree Fahrenheit will change the speed of sound by about 1 fps proportionately with temperature, as a quick and dirty rule of thumb.

Now, the reason I need said numbers and values is to calculate the air mass in the tank, plenum, and thus the amount of air per shot and how many fpe per grain of air you get. For instance, every website I've visited that puts out the specifications on the FX Impulse in 22 caliber shows that the 22 outperforms the other calibers by around 200%, which is ridiculous. I did some simple ratios and proportions then it did not seem right so I did some statistical mechanic formulas and it appears that the FX Impulse M3 is very close to the proverbial perpetual motion machine; in other words, impossible, and not just improbable. 

Once I get your numbers and crunch them down to the individual grain of air at 1 atmosphere you will see that it only has so much energy, and in order to take advantage of it while being as efficient as possible, you must back down from the highest power peak, which means you want the valve open for no more than 7 inches of pellet barrel travel so you have the most efficient pressure at the muzzle as the pellet exits. If you get a few fps above, you will also have a much higher pressure which translates to wasted air for the small velocity increase. 

In addition, shot count and power are on a teeter totter balanced by a fulcrum that is the compressed air pressure and volume in cc. You cannot increase power and shot count unless you raise the cc, or pressure, but better both, so set your goal and let the shot count fall where it may, of course you can have the most shot count with your goal velocity is you adjust everything in unison for the most efficiency at your goal velocity. 

Lastly, I presume that you have a 580 cc bottle at 250 Bar (3,626 psig, or 3640.7 psia, which absolute pressure is needed for the calculations), which better would be a 300 Bar bottle, but I'll calculate with 250 Bar. Said bottle at said pressure contains approximately 2,660 grains of air at 70 degree Fahrenheit. If your regulator is set at 115 Bar, which is where I would start, The 115 Bar (1,668 psig) pressure is like a preload where every shot is at that energy level, and at that energy level preload has approximately 1,219 grains of air that will not be used as it is there to hold the preload pressure of 115 Bar; therefore, the difference of 250 - 115 = 135 bar (1,958 psig), which equates to 2,660 - 1,219 = 1,441 grains of AVAILABLE air for the shot count from full fill down to the regulator pressure. Now, I can predict how many shots you can get with an efficiently tuned gun that uses 4 grains per shot, but first I need the mass and velocity, or fpe of any of the shots in the string, so lets say your 18 grain pellet travels at the best combination of accuracy and power of 889 fps, which would give you approximately 31.58219265 fpe, if you were at sea level and at 45 degree latitude, else, you might be a millionth of a fpe off. Great so far, we'll round it to 31.6 fpe then we divide by 4 fpe per grain of air to get 7.9 grains of air per shot. Then we divide the 1,441 available grains of air by the 7.9 grains of air per shot, and we get 182.4050633, but we only recognize integer shots, so the shot count would be 182 shots as a prediction. With the numbers you provide, we can adjust the air usage. Remember, you only have 1,441 grains of air available, and not 1,442, which means there will be those that will claim that they can get more energy out of 1,441 grains of air at 70 degrees Fahrenheit, and those people I would have to agree with because that is how wars are started.

In conclusion, the laws of physics are not just really good ideas, and numbers do not lie, but you can lie with numbers. I almost ordered the 22 caliber FX Impact M3 with the 700 mm barrel because I loved what I seen, and I'm not talking about the rifle, but the numbers, but after crunching them, I think i am going with the 25 caliber, unless I get my prototype patented and book finished with entertaining-educational videos to follow.

Take care, stay safe and Godspeed.

FJB Out!

Marl3y, I forgot to mention the FX Impact M3 specifications, here they go:

0.177 35 fpe 375 shots 13,125 fpe total 4.9 fpe/gr. air

0.22 79 fpe 330 shots 26,070 fpe total 9.8 fpe/gr. air

0.25 89 fpe 160 shots 14,240 fpe total 5.353 fpe/gr. air

0.30 124 fpe 105 shots 13,020 fpe total 4.895 fpe/gr. air

0.35 156 fpe 45 shots 7,020 fpe total 2.639 fpe/gr. air

I calculated the fpe total by multiplying the fpe by the shots. I also calculated the fpe/gr. air, and that is what stood out like a sore thumb. How can the 22 caliber be more efficient than the 0.177? The 22 caliber is almost 200% more efficient than the other calibers. I calculated it to be at most 179 shots at the best case scenario

Cool?.

Awesome!

Amazing what two little spacers can cause so much preload. What Bar pressure did you settle at? How far from my 115 Bar? 

Lastly, do you get anywhere the 330 shots stated on many websites describing the 22 caliber FX Impulse M3?

I'm thinking that marketing used the lightest pellet, set at the lightest pressure and adjustment to where the pellet just popped out of the muzzle, and then used the heaviest pellet at the highest setting to get the 79 fpe because there is no mention of velocity or pellet mass used for both values of fpe, and number of shots.

It's not easy to decide which pcp to go with when advertisement and marketing are playing with the numbers.

Lastly, I suggest you stick with the 25.39 grain pellet at 889 fps and learn the trajectory curve so that you can place the pellet at any range with minimal prediction and zero guesswork; for example, said mass and velocity aimed at a target 100 yards will have an apex, or highest point, of 18 inches above the line of sight, and when it lands on target at 100 yards, it is coming in like a mortar round, so closer targets you will shoot too high, and farther targets you will shoot too low because of the trajectory arc not being a perfect parabola, but a cycloid after the apex, which is where havoc plays with over spun pellets of over 40,000 RPM spin and changing dynamic gyroscopic and gravitational forces fighting each other and who ever wins, determines which way the wobble helix will transpire. It will all be covered in my book with numbers, formulas and equations that can be tamed with a $13 Walmart calculator. 

Enjoy your your shooting and gun.

Stay safe

FJB Out!