My first recommendation, as with any new (or "new to you") firearm, would be a disassembly, inspection, and thorough cleaning and lubrication. Check the internals, including the extractor and magazines, for damage. Be sure to include the magazines in your cleaning.
If the cleaning and re-lubrication doesn't have the desired effect, next up would be a new recoil spring. If OEM springs are unavailable, Wolff offers spring of different rates.
If you still have the same issue while attempting to tune your new recoil spring to the ammo, and have ruled out physical damage to the magazine itself, the next replacement would be the magazine springs, or new magazines, if the existing ones appear damaged.
Ammo, as always is also a key component in this scenario, so be sure to try different types and brands of ammunition.