If you are experiencing problems with breaking strings then this article may help isolate some issues.
”Strings do break from age or because of a flaw in the string but most string breakages are caused by a problem with the instrument…”
Martin M145 Bronze 12.5-55 LIGHT/MEDIUM
Martin Bronze Strings are excellent for daily use. Deep, rich bass tones and crisp, ringing trebles.
Martin 80/20 Bronze is an alloy comprised of 80% copper and 20% zinc. 80/20 bronze strings provide a very brilliant tone when they are initially put on the guitar and mellow over time.