can anyone confirm if riveted extractor on 600 series is same as 700 riveted extractor ?
Yes same riveted extractor is used for the 600 as is used in the 700, within each cartridge family, .222, .308, or .350 mag.
From Brownells . . .
BROWNELLS - REMINGTON 700 RIVETED EXTRACTOR KITS
Replaces the no-longer-available Remington factory part to keep older rifles shooting. A fast, economical, alternative to returning rifle to the factory for repair. Replacement requires no modification to bolt or rifle. Fits all variations of 700, 600, 600M, 660, 742, 760, 788, 40X and XP-100. Large fits calibers with .473" (12.01mm) diameter case head, including .22-250, .243, .270, .308, .30-06, etc. Small fits calibers with .378" (9.60mm) diameter case head, including .17 Rem., .222, .223, etc.