Glad to find this thread. I have a TSO in .40 and have seen many of the issues you all have. Loose rear sight, buffer gets destroyed with low rounds, and I certainly agree the mag well fit is the worst. However, I am having a different issue I need help to solve.
I am having FTEs at a rate high enough to get one or two in a match. The spent round is not fully extracted and the slide goes back and grabs a new round and jams it under the round that did not extract. This gun is as it came from the factory with the exception of me removing the buffer. Thanks in advance!