polygon barrel tolerance?

[Scragglygoose]

Hope I'm asking this in the right forum. I have a CZ-82 9x18 that has the polygon rifling. If I drop a .356 bullet down the bore it falls right through, a .357 dia. bullet has a small amount of drag but can be easily pushed through. I know I can't drop a .356 bullet down the barrel of a 9 mm pistol so is this normal for a polygon barrel or is this thing just shot out? The pistol has a 1983 manufacture date on it and it looks very good overall.
Thanks

 

[Bill DeShivs]

8X18 uses a larger bore diameter.

 

[Scorch]

9X18mm Makarov uses a .363" bullet instead of a .355" bullet common to most other 9mm pistols.