So I recently purchased a second FX Impact in the .22 cal compact version (500MM barrel). I also own a 700mm .25 Impact X that I added a Power Plenum to. On the .25 cal, with the Reg at 110 bar and the valve knob at two lines, it’s slinging 26g hades at 990-1000fps. The new compact won’t get 15.89g hades over 935fps. I haven’t pushed the reg about 110 on the compact but it seems to plateau. I really don’t think the barrel length makes that drastic of a difference but am stumped on this. I believe the .25 had the heavier hammer weight and stiffer spring, can that be it?
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Tuning FX Impact Compact .22/PP max velocity
- Thread starter AirgunnerSFL
- Start date
Well looks like the old Impact-X is pushing 57fpe and the new one only 30fpe so I would say the barrel does make quite a difference. Then again so does caliber, pellet weight, porting, hammer weights and springs and plenums.
It's difficult to compare two entirely different guns. One built for long range and heavier ammo and one built for short range and lighter ammo.
It's difficult to compare two entirely different guns. One built for long range and heavier ammo and one built for short range and lighter ammo.
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My Compacts reg is@ 95 bar and shooting 15.89s at 925 fps, when I had it @ 105 bar was shooting 18s at 925-930.
So you should easily exceed 933 with 15.89s.
And yes barrel length makes a huge difference in velocity.
With my current tune, reg @ 95 bar, just barely 3rd line showing on the valve rod, and lot's of slack on the hammer spring I'm getting 925fps with15.89s and at least 60 shots on a fill with the 500mm barrel.
With the exact same tune installing my .25 600mm barrel kit with no other changes, I'm getting 915fps with the 25 grain JSBs
So you should easily exceed 933 with 15.89s.
And yes barrel length makes a huge difference in velocity.
With my current tune, reg @ 95 bar, just barely 3rd line showing on the valve rod, and lot's of slack on the hammer spring I'm getting 925fps with15.89s and at least 60 shots on a fill with the 500mm barrel.
With the exact same tune installing my .25 600mm barrel kit with no other changes, I'm getting 915fps with the 25 grain JSBs
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if it helps- The difference between my 700mm & 500mm is around 14% velocity with 23 grain slugs.
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My 500mm fx crown does 50fpe with room for more in 22 cal. Not a mkii either
Yall need more reg pressure to make good power on a shorter barrel. Valves are more efficient at higher pressure typically. And having higher pressure in the plenum equates to more system volume. I'd think running higher pressure would yield an equal shot count or pretty damn close
Yall need more reg pressure to make good power on a shorter barrel. Valves are more efficient at higher pressure typically. And having higher pressure in the plenum equates to more system volume. I'd think running higher pressure would yield an equal shot count or pretty damn close
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When I pushed the reg up to 110bar, the gun had a horrible extreme spread- It would peak in the low 940’s but range from 925-940’s.
Lemensd sounds like it’s in line with yours. I’m going to try the power kit and see how that helps.
I want to shoot the hybrids out of this gun out to 75 yards and would like to get them in the 900’s. Hopefully that isn’t asking too much out of this gun.
Lemensd sounds like it’s in line with yours. I’m going to try the power kit and see how that helps.
I want to shoot the hybrids out of this gun out to 75 yards and would like to get them in the 900’s. Hopefully that isn’t asking too much out of this gun.
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Airgunnner
Are you adjusting your hammer spring? You have a bad tune going, you must increase your hammer spring tension with increased reg pressure, but I'm sure you know this.
We are not inline mine is at 95 bar and 925fps very consistently with the 15.89s with a low extrem spread, plus my first shot of the day is within 4fps of all following shot's. I don't need to blow off that first shot like so many people do.
When I had it at 105 bar 18 grain JSBs were flying at 925 the 15 grains would have been 960fps. And with the 600mm .25 barrel kit installed with these same settings JSBs 25 grains 925-930 and both tunes were consistent and efficient.
I tried the FX Hybrids in .25 @ 900 fps and was unacceptable grouping's even at 35yrds. That's with the above setting of 105 bar same tune but velocity was consistent.
That's when i backed it down, improve shot count to aleast two mag's (56) shot's.
So now at 95 bar , 15.89 .22 cal @ 925 fps and just swap to the .25 cal 600mm barrel kit 915 fps on only one tune, change nothing but the barrel. Both calibers are very consistent and efficient , right at 60 shot's each on a fill.
That was my goal, one tune with two different calibers , that's why I went with the .25 in 600mm to get the velocity where I wanted and at the same time in .22 in 500 mm barrel for a flat out to 50 yrds trajectory. No retunning, between caliber changes.
Sorry if long winded, but you should easily exceed 940 with the 15 grains plus make it very consistent we had some fine tuning.
Are you adjusting your hammer spring? You have a bad tune going, you must increase your hammer spring tension with increased reg pressure, but I'm sure you know this.
We are not inline mine is at 95 bar and 925fps very consistently with the 15.89s with a low extrem spread, plus my first shot of the day is within 4fps of all following shot's. I don't need to blow off that first shot like so many people do.
When I had it at 105 bar 18 grain JSBs were flying at 925 the 15 grains would have been 960fps. And with the 600mm .25 barrel kit installed with these same settings JSBs 25 grains 925-930 and both tunes were consistent and efficient.
I tried the FX Hybrids in .25 @ 900 fps and was unacceptable grouping's even at 35yrds. That's with the above setting of 105 bar same tune but velocity was consistent.
That's when i backed it down, improve shot count to aleast two mag's (56) shot's.
So now at 95 bar , 15.89 .22 cal @ 925 fps and just swap to the .25 cal 600mm barrel kit 915 fps on only one tune, change nothing but the barrel. Both calibers are very consistent and efficient , right at 60 shot's each on a fill.
That was my goal, one tune with two different calibers , that's why I went with the .25 in 600mm to get the velocity where I wanted and at the same time in .22 in 500 mm barrel for a flat out to 50 yrds trajectory. No retunning, between caliber changes.
Sorry if long winded, but you should easily exceed 940 with the 15 grains plus make it very consistent we had some fine tuning.
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My .22 Impact compact is at 120 bar on the reg. hammer wheel on max and hammer spring adjusted to 16.5MM gap. Valve adjuster is at the 4th line.
Shooting the FX Hybrids at 900 FPS for 2 full mags.
Good accuracy out to 50 yds. and shot count is plenty good for hunting.
Shooting the FX Hybrids at 900 FPS for 2 full mags.
Good accuracy out to 50 yds. and shot count is plenty good for hunting.
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