[John Sabato]

While the follower button may be hanging up on the inside of the grip as Dwight has suggested, there is another distinct possibility. If the magazine tube is even slightly crushed, warped, or bent it may not enter the frame without strong encouragement, or not at all.

If this is the case, I would recommend you send the offending magazine to G.T., as he has created (machined) perfect mandrels for ironing out the issues (literally).

I received a warped magazine in an ebay transaction about a decade ago, and the seller refused to make good on it. G.T. made that magazine as smooth as it was when it left the factory...and I never have had another problem with it in any Luger.