I recently swapped out the grips on my ‘A’ series (1970’s) Model 41 to a Nils grip that fits my hand better that I bought second-hand (they appear unused otherwise - original owner went with a different way). At first install the magazines would not seat to the locked position where they clicked into place. I removed the grips, and carefully examined to see if I could detect where any interference may be causing this. It seemed like the spacing around both the mag release and slide release, though very snug, does not interfere with their movement, and I could not find where the problem was being caused, though tolerances generally seemed to be very tight. I reinstalled the grips and lo and behold, the magazines now will click in firmly. The satisfaction was short lived. I took the pistol to the range where at first it fed and functioned just fine, but after running a few magazines through it (all stock SW mags BTW which have never before exhibited any issues), the magazines would start to release and drop on their own upon firing the pistol (always on firing with no delay at all), in spite of having clicked into place firmly (I would check by tugging at the bottom of the mag).

My question is, where should I look for interference that might be causing this to happen? I’m handy enough with a Dremel tool to be able to alter small details, but other than the release button, which appears to have no interference issues, I do not know where to look. Thanks in advance for any suggestions.

Any chance the grip panels could be shifting during firing? Such movement could cause malfunction by interaction with the catch or the catch nut. (release button)

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Ret. LE, FA Instr, S&W Armorer

If the mag clicks in place, but falls out after firing there is movement between the grips and the frame. The grips must be interfering with the mag release or your finger bumps the mag release when the slide cycles.

The big questions are "How to stop the grips from moving?" or "How much movement is acceptable?" .

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S&WHF 366

I'm just back from the range and I'm pretty sure I figured it out with some careful troubleshooting. I didn't notice that there was a "sub-button" that is at the 12 O'clock position on the mag release button. It's easy to miss as it's tiny and flush with the frame and almost looks like part of the release button (but it operates independently). There was no cutout for that tiny button on the Nils grip so it was not allowing it to protrude the tiny bit it needs to when a magazine is inserted. I could see on the grip where it had made a mark. I carved out a tiny cavity which allowed the button to move (protrude), and that instantly fixed the problem. 300 rounds and not a hiccup!

Good for you and Welcome to the Forum also.

Thank you, Barrie!