The small reciever rifles have all got long trigger pulls. They usually wear-in quite smooth, but the distance of travel is always an issue, compared to a "GOOD" trigger like a Webley or Rekord.
This helped on my gun:
A simple trigger stop. Overtravel movement is greatlly curtailed and it really helped with consistancy and it's accuracy!
Secondlly, CZ has a number of Factories, each making their line, but several versions of the 618-624 guns were made. In the five 618's I've had, there have been 5 different versions! Each a little different. The latest has a 624-type, barrel pivot lock screw. Some have grooved recievers, some not. Serial # on some (Various places too!) I guess each factory has their own "Proofs"?
The pictured rifle is a Raven-18.
Everything is CZ, far as I can interprate.However, the rifling DOES continue through to the Breech (contrary to the oftfound "Open Chamber" (for use of European Round Lead Shot), The reciever is grooved for the tiny CZ Scope, and the barrel is grooved for a front sight hood (missing). Crowning is different from other 618 bbls. Velocity is around 370-390fps, in .177 Cal Now that may seem slow, but accuracy is astounding! I've targeted the little Bugger out to 40 yards! My normal sight-set is 20 yards for it.
A former Owner apparentlly "tuned" the guts for smoothness. I stripped, Stippled, restained, and Laquered the stock (7 coats, if I remember right? Hand rubbed.) I did the trigger stop, and deburred all metal edges (needs a re-blueing someday...)
HTH,
ZVP