Tuning Tuning Impact M3 .22 for shooting slugs at 100m

[nerijus]

Hi, I am looking for tuning advice to shoot slugs 1MOA at 100 meters. I can get good groups at 50m but at 100 it is all over the place. 3-4 MOA is best I can do.

My setup is:
.22 700mm sniper version
Superior Heavy Liner
Carbon sleeve
FX Integrated Harmonic Barrel Tuner Shroud

What I have tried so far is different slugs: JSB KnockOut 25.39, ZAN 28gr, 30.5gr, .217 and .218, H&N 30gr .217. With all getting very similar result. After some initial testing I thought that ZAN 28gr .218 would be best.

I tuned my m3 to shoot at different speeds: 958, 945, 935 and 916 fps. I follow the 95% rule for tuning, and cut 10-20 fps by valve adjuster. At all speeds I was able to get spread of 5-9fps. I got like 8 shots in a row at the same speed of 958fps. Second reg at 142bar, first at 175.

Shooting at 50m target I got best results at lowest speed – 916fps, 1st reg 122 bar, 2nd 155. STD 1.2

After getting constant shots, I would play with harmonic tuner, shooting 8 targets 5 shots groups, turning by one hash mark:

After 50m I move to 100 and the result is disappointing 3-4 moa. So, what would you suggest?

 

[Airgunmann]

Keep trying different slugs give NSA slugs a try people have good luck with them also

 

[CBuasri]

Old post ut here are my 2cents.

It might just be the barrel. As good as FX barrels are they can't be 100% good.
You just have a bad barrel.
Make sure there are no play or slack in the barrel housing. Get a carbon fiber sleeve or install more O-ring with the tape trick like Matt from South Africa does to keep the o-rings in place.
Also, if you have your old superior line, install that back and see if it still performs the same.
Those grain slugs will be alright going through that liner.
Really anything pass 34gn, I would use the heavy liner .

 

[Juice13]

What are your regulator settings?

 

[bigHUN]

The Reg must be high.... you need a high pressure with short dwell.
Also check the liner crown.
A long dwell will make the air catch the projectile edge at the muzzle and there 90% the errors start.

 

[N1neWivesSniper]

Old post ut here are my 2cents.

It might just be the barrel. As good as FX barrels are they can't be 100% good.
You just have a bad barrel.
Make sure there are no play or slack in the barrel housing. Get a carbon fiber sleeve or install more O-ring with the tape trick like Matt from South Africa does to keep the o-rings in place.
Also, if you have your old superior line, install that back and see if it still performs the same.
Those grain slugs will be alright going through that liner.
Really anything pass 34gn, I would use the heavy liner .

Anything past 25-grain is heavy liner on .22