Originally Posted by Any Cal.
The extra power spring will reduce the time available for ammo to feed, as it increases slide speed on the return. The stock spring comes back fast, and goes forward slowly, allowing the ammo to rise in the mag. If you are 'overrunning' the ammo in the mag, it is because the extra power recoil spring. You can see the difference in slow mo quite easily.
That is exactly the problem I've had with heavier spring weights and hot ammo. Nose-up FTFs. No such problems with the factory spring.
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