Extractor marks are not that uncommon with gas guns and heavy turkey loads. The slow burning powders required to keep pressures in check produce a lot of gas. Gas operated guns that do not have some sort of self regulating gas system that vents off excess gas can sometimes eject the shell with too much force, which causes the extractor mark. If the gun does not leave the mark with target loads, that is likely the issue. The 20 gauge was/is designed to shoot shells with a maximum of 1.25 oz of lead shot, and we are shooting quite a bit more payload than that with TSS turkey shells.
Other than polishing the chamber to reduce friction when ejecting a fired shell, the only real fix is to shoot shells with a different powder or lighter payload. If you handload or know someone who does, they could reduce payload to 1.5 oz, 1&7/16 oz, or even 1&3/8 oz to see if that eliminates your issue. If you do not have access to handloads, Foxtrot makes a 1&3/8 oz load (other manufacturers may as well). Pumps, single shots, O/Us, and inertia powered autoloaders do not leave those extractor marks because they are not operated by high volumes of gas that cause the fast operating cycle.
