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VK Slugs on my FX Impact X .22

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Ya that probably wasnt to clear. My 600mm liner is 16:1 twist rate and some are getting good results but only if everything is tuned perfect. It seems as if the 15:1 twist rate and extra 4" that the 700mm offers is more user friendly. Just like the pic rflops3 showed above, all those groups are unreal at 100 meters and all on the same setting unless I missed something. I cant do that at 50 yds. consistently yet. I have shot groups like that a few times but the next group might be 1" or more then 3/4". I have done lots of tests with the chrony and my spreads are extremely good so this is where I am at, I think the slugs do better if shot faster but if I turn it up to much it gets worse. I just think there is to much unused air when the slug reaches the end of the barrel and the turbulence upsets the slug. If I turn the power down I dont think the slugs spin fast enough. So what I should have said was settings dont have to be so perfect, not people when using a 700mm vs 600mm. I still think I can hit a good combo with the 600mm but these slugs are not cheap so I am looking at all options. Using less air with the 700mm to get the same fps as I can get with the 600mm seems like a huge advantage.
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Yeah. What I found is that air is one big key. Too much air and all goes wrong. I have spent over 150 slugs to properly tune the gun. For you to ave an idea I'm now able to do 100 shots with JSB monsters @ 980ft/s but the slugs uses almost the double of air. I don't know why but when I shoot slugs, I can get no more than 75 shots consistently at that speeds.

I think that the valve steam is your friend on this. Get it fully opened, crank the reg and hammer spring until you get at least 10 ft/s higher than you want and then with small 1/4 turns get down to the velocity you want.
 
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Starling,

For best results, shoot for 920 to 950fps. Don't go higher unless you don't mind dealing with negative effects from supersonic airflow around the slug.

Tune the gun like Ernest shows, to minimize turbulence behind the slug when it exits the barrel.

One final step is to check accuracy at 25 or 30 yds.....3-shot groups. They should all be touching or better. If not, use the valve stop one notch or less at a time to slightly increase or decrease velocity, and check accuracy with a 3-shot group after each adjustment.

Each adjustment you make will change the harmonics slightly. You're searching for an accuracy node when doing this. You should find one within 10fps on either side of your target velocity.

When your groups at 25 to 30 yds are all touching or better, you've found an accuracy node and should get good groups at 100yds.

Also, I've had great results with the O-rings on the barrel liner.
 
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Starling,

For best results, shoot for 920 to 950fps. Don't go higher unless you don't mind dealing with negative effects from supersonic airflow around the slug.

Tune the gun like Ernest shows, to minimize turbulence behind the slug when it exits the barrel.

One final step is to check accuracy at 25 or 30 yds.....3-shot groups. They should all be touching or better. If not, use the valve stop one notch or less at a time to slightly increase or decrease velocity, and check accuracy with a 3-shot group after each adjustment.

Each adjustment you make will change the harmonics slightly. You're searching for an accuracy node when doing this. You should find one within 10fps on either side of your target velocity.

When your groups at 25 to 30 yds are all touching or better, you've found an accuracy node and should get good groups at 100yds.

Also, I've had great results with the O-rings on the barrel liner.
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Always learning from the best. Thanks for the tips Bob. I'm also using the orings on the liner as well. Maybe the tuning or the gun itself or me as shooter but on my testes unless the slugs go high on speed they do not perform as well . But I confess that I didn't try as hard on lower velocities as I did on high velocities.
 
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Good Shooting! small changes make a huge difference, monsters redesigned are amazing with the SlugLiner ... and pellets in general... FX DISH ALL THE OTHER LINERS! 😅

This weekend I was testing the 18gn jsb out of the slug liner just for fun and they are good too! 

If you want to go up to 30gn, next good change is a big bore valve seat. 
 
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I have a curiosity. My MKII will arrive later this month. What should I expect about velocities out of the box ? (Assuming of course that the reg is at 150, maxed hammerspring and elongated TPs).
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Nothing extraordinary if you already have the X. To have a baseline, I will say around 930-960 the Monsters with the mods you mention @ 150b
 
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