Hello,
I have a new style R&R Open shotgun. Shotgun seems to run best with Win AA Supersport 1oz 1350 FPS. The 16lb spring in came with was too week and had a lot of problems with the bolt not fully returning to battery. Also I experience a issue you describe above where the shell ejects perfectly, bolt returns but doesn't strip a shell from the mag.
So I have changed the front spring to 18.5lb. The bolt is retuning to battery nicely and shell still eject with out failures, but I still have the issue not stripping a shell a lot more often then I like.
I ordered a calibration set of Ext