Problems tuning impact with donnyfl koi *Solved*

[Danielswe]

Just got my brand new donnyfl koi mounted on my impact mk1 25 cal but cant get any good groups, its really bad.
Im not complaining about the silencer im sure its me thats missing something when i try to tune the gun.
Im shooting with jsb heavy mk2 875 fps and target only 110 feet away 5 shot groups spreading about 2.5 inch.
I tryed many settings from 860 - 910 fps but nothing seems to help. after every setting i shoot 1 mag ( 16 shots) before making new adjustment.

Can anyone please help me figure this out because i really like both the look on my gun with the donny and that its much quieter .

Sorry for the wrong spellings -

 

[Gerry52]

What's happening if you shoot it w/o the Koi? Is it still squirrely or shooting well? Did you go one size up on the Koi (.30) or did you get a .25?

 

[Danielswe]

I Had no problems with nice groups before .
I didnt go up in size on the koi, got a 25.

 

[MrP]

9 times out of 10 when I’ve had issues like this it has been clipping… sometimes very slight clipping that is not immediately obvious to the eye.

Make sure everything is snug and tightened up. If you have O-rings in your adapter and between your adapter and the moderator that can sometimes prevent it from seating dead center.

 

[badger5th]

I have a Koi for my Crosman 2240, great moderator, no clipping with the .177/.22 size. If you suspect pellet clipping I suggest taking the end cap off and looking for shavings. The monocore in the Koi is aluminum and harder than lead. The edges may shave off bits of lead.

 

[Gerry52]

When I got a Donny Ronin for my .25, Donny told me to go one size up & get a .30 moderator. I'm glad I took his advice.

 

[Airgunmann]

Check it over real good for clipping if nothing else you could open the holes in the moderator to 30 cal size

 

[Danielswe]

Thanks for all the advices . Will try and check everything today.

 

[Danielswe]

Checked the moderator today real good with a flashlight..It was clipping ! When looking with the light it was really easy to see lead marks on the baffels and end of the tube, looks like it just painted the moderator a little with lead and no big marks. Drilled it out with a 9mm drill ( maybe 1 mm more than original) and now it shoots like a good impact again
Thanks again for all the tips making me find this. Beer on me if u visit Sweden

 

[MrP]

Awesome. I went through this recently with the Rex p I just got. I assumed my tolerances were OK on the moderator and I was starting to question the quality of the barrel…

The clipping was so light that it wasn’t even damaging the 3d printed plastic baffles - barely skimming the surface - but still affecting poi

 

[TheCarFather]

I also delt with this very same problem on my Cayden with a buck rail moderator. It was driving me crazy and was so relieved when I finally discovered the problem.

 

[Danielswe]

I agree, clipping looked like it didnt even damage the paint but still gave a very bad poi. And the dealer told me that the only chanse for clipping is if i accidently doubleload ( never happens to me but happens everytime some friend is trying the gun *grr* ) so when i first looked for clipping i did a really sloppy job . I know the feeling Thecarfather !! yesterday i was going thru youtube for all the tuning tips and tricks... tryed everything and shot about 250 shots *lol*
Im soo happy i found this forum and became a member before i sold the gun