I have a .22 cal rifle that has a JM Monolith kit installed and tuned by Ed K. When I shoot it, I can easily keep JSB exact or Logun Penetrators (16 gr) between 3/4 and 1/2 at the 50 yd outdoor range at the gun club. Of course this depends on the weather and my skill etc. It shoots almost as well as my 2 PCP (Logun MKII and a AA S410ERB) but doesn't require any charging gear. Yes it is somewhat heavy, but that is relative, as my RX-1 weighs almost as much as the M54. I think it's a great rifle and it's definately a keeper.
V/R
Nathan