Two things:
Make sure that you have the latest magazine follower. It is the rounded one... Not the more angular dog-legged follower.
Make sure that you have the new "flat" recoil spring. The original is the rounded spring type and does not hold it shape or tension very long.
Both of these items can be obtained through Sig CS for free. Call them and you will have the replacements in less than a week.
I received the new "flat " recoil spring & installed it & will give it a work out tomorrow. The other part was B/O. BTW, it took about a week sent via FedEx.