Tight spot in bore of CZ 17 HMR American...

When my CZ was new it shot slightly better groups. Some of the folks here recommended not cleaning the 17 until accuracy dropped off (up to 200-300 rounds). After a little experimenting, I found the accuracy dropped in mine after 20 shots requiring cleaning.

Tonight I really cleaned the bore and finished it off with Flitz. When Flitzing a tight spot near the chamber in the throat are became obvious. It was really tight for .5"-1.0" near the chamber until it was Flitzed. Now its smooth and consistent.

Any of you guys experience this? Theory is that accuracy drops off when a projectile is sized down early in the bore and the bore opens up.

The CZ shoots, but its no where near the performer some of you guys claim. A family member Savage easily shoots as well if not better. A 22 Mag shoots as well too!

Any of you guys have this problem and did it help the accuracy?