Conundrum

[Lordgower]

Conundrum

I am shooting an Onix Reload in .22. At ten meters it shoots very accurately. It has an adapter on the barrel for a moderator and I am using a Red dot sight. However, when a moderator is fitted, an HW, it shoots 15 centimeters high. Taking the moderator off and it shoots accurately again. On checking the moderator there does not appear to be any “clipping” and the same item on a rifle does not make any difference to the rifle’s accuracy.
I would be grateful for any explanation and any suggestions to alleviate the problem!
Thanks.

[B&W FOX]

The moderator changes the barrel harmonics

[Turnup]

I don't expect that barrel harmonics can move POI by 15 cm at 10 metres - that is a huge change!. It must be the mod either clipping or not quite centred on that rifle. You could try to catch a pellet in something very forgiving and see if it has clipped. Also try fitting a washer between the barrel and the mod - those fibre plumbing washers come in 1/2" and should be a good fit. If still strugling then try adding about the same weight to the end of the barrel (without the mod) and see what effect that has.

[evert]

Try sighting through the barrel/moderator, and look for misalignment.

[WesseH]

Maybe a bit late but is the moderator tapered steeply?
Is the moderator pressing on the air cylinder perhaps?
That would cause the barrel to be elevated thus resulting in such a huge difference in POI...

[webtree]

check the mating surfaces and threads i have had rifles in the past that have been screw threaded wrong or the shoulder where the mod fits up to is damaged