Thread: Shortening a CZ455 varmint barrel - how short to go?

Running into problems with 22LR subs pretty much all going supersonic in the 20" barrel. Previously there was the odd one which would do it, but as the barrel has now had just over 1000 rounds through it, it's obviously just broken in, and the normal condition is supersonic "subs".

This is quite a problem, as most of my shooting is around orchards with a spotlight. The neighbors are more than happy for the shooting, but just don't want to hear it. A supersonic crack is hard to ignore.

So my question is....how much to chop off? I was thinking a 14" barrel would do the job.
Has anyone else done this, and how does it shoot? Is there a noticeable drop in muzzle velocity?