[mrerick]

Put some masking tape on the back of the frame under the place where the receiver toggle contacts it and the frame stops the toggle.

Load a single round, and manually cycle it into the Luger. Leave the magazine in place

With a single round chambered and the magazine in place, aim and fire the Luger while focusing on a good supporting hold in which the recoil force will travel back through your bones and your body absorbs the recoil.

Check the tape to see if there is excessive force against the frame, no force against the frame or just a little.

Repeat the exercise a few times after changing the masking tape.

This will help you understand if the toggle mechanism is being driven back with too little or too much force, and will help you judge your grip.

If you can just see the marks from the toggle on the tape, the recoil spring and balance is probably pretty close to being correct for the ammunition you're using. If this is consistently the case, look to the magazine and also to your grip as the possible source of the feeding problems.

If everything is correct, load two rounds, chamber one manually and fire two. Observe the masking tape. Feel the recoil impulse.

if this works, try with three rounds. Continue until the stovepipe / misfeeds return or things are working properly.

The Luger is a balanced mechanism where too little or too much recoil compensation can lead to feed problems.

Always address your stance and hold before you start changing out things. Then start with a known good magazine. The best in my experience are the wartime or post war DDR Haenel Schmeisser / Thalmann manufactured "fxo" "E/37" or "1001/2" marked magazines.