The heavier mainspring may reduce the amount of felt recoil (more resistance for the hammer needed to move), but will put more weight on the sear.
Watch your ejection of empty casings. The recoil spring works with the main spring.
And the primary job of the recoil spring is to return the slide to battery, secondary is to assist with the recoil of the slide moving to the rear.
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Former President of the ECPT (Eifel Combat Pistol Team)