I'm not exactly sure what a thin walled or the heavy walled description means. CZ has two different Varmint barrels as far as I know. There is the 527 Americanized one that's about 24 inches long and the 527 European Varmint that's about 26 inches (25.6"?) long. The barrels taper may be different. Both Varmint barrel lengths have been imported to the U.S. You might give CZ-USA a call and ask what the difference is between the two.