I have a Kadet kit from the late 1990's when CZ first came into the U.S. I have put thousands of rounds through the kit on my CZ 75 frame. I have noticed no loss of accuracy, if anything perhaps it is even more accurate. I believe that CZ uses a hammer forged barrel in their Kadet and current Kadet .22 lr kits, for the CZ 75, P0 7, and P0 9, kits. Seems like shooting out a .22 lr barrel would take perhaps a lot more than 50,000 rds.
In fact my Walther PPK in .22 lr which was made in 1967 has had well over 50,000 rds throughout the years, has had no loss of accuracy, and in looking in the barrel I can notice no wear. It was one of my first handgun, and back in the day 500 rds of .22 lr ammo could be had for sometimes less than $5 per brick, and it was a cheap shooter compared to the PPK .380 caliber I could have purchased at the time.