A lot of confusion seems apparent on what is a chest measure and what really is pit to pit etc.
I have 15 years in retail and around 1500 sales of tracks and polos without customers present.
firstly a 25 inch pit to pit does not make a 50 inch chest top, design does not go hand in hand with chest size.
If you want to buy a top the best method is to measure a similar top you own and if it fits to your liking then look for a similar pit to pit measure top. If you want bigger a 1inch pit to pit increase is a 2inch total increase.
A basic rule i believe if you prefer not too tight then always go up a size. If you are happy to squeeze in a top then go down a size.
Dont take any notice of xl, xxl 3xl unless you are 100% familar with the brand/ country etc even brands follow trends and change their sizing each year. the current trend is a slim fit trend so many people wanting similar fits they are used to must go up a size to maintain their fit.
If in doubt ask we are on the end of a phone