S&W M&P .22 (the Walther made one) Feeding Problem

So, I've had this Carl Walther-made M&P .22LR for years. https://www.smith-wesson.com/firearm...hreaded-barrel

It has run just fine (pretty much 100% with ammo like Mini Mags), even with the added mass of an RMR added (thanks to Mark Housel). I keep it clean and lubed.

In the last few months, however, it has developed an issue. At slide lock, after I insert a loaded magazine, and drop the slide with the release, the first round fires normally. About 50% - 75% of the time, however, the next round isn't fed from the magazine. USUALLY, the fired round is ejected cleanly, but not always. So I go click on an empty chamber. If I hand cycle the next round, the rest of the shells in the magazine will usually feed OK. USUALLY.

So far, I have changed the recoil spring, and cleaned the magazines and installed new mag springs (I have three, and the problem happens with all of them). The problem persists.

I then tried loading various numbers of rounds in the magazine (from the capacity of 12, down to 4-5). The problem persists.

I have tried different ammo (the aforementioned Mini Mags, Aquila, Winchester, and other standard and high velocity rounds). The problem persists.

I think/thought the issue was related to the springing, either that the slide was returning to battery too fast and/or the magazine spring was failing to push the next round up for feeding into the chamber.

But I'm pretty much out of ideas. Any suggestions would be GREATLY APPRECIATED. THANKS IN ADVANCE!!

Try a new magazine? The followers do wear out over time.