So when you say you are supporting or bracing the mag, you are consciously pressing up on it? It's almost sounding like the toggle isn't going back far enough. I personally view Wolff springs with suspicion, like they are one-size-fits-all or universal in nature.
Some masking tape of the back of the frame to see if the rear toggle link is hitting the frame on recoil may be the next test. If the tape isn't being hit at all then you may need more recoil or less spring.
I am assuming that the gun is clean and very generously lubed?
dju
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