Despite being in a warzone MASH’s Hawkeye always refused to carry a gun, but the one time he was forced to would underline something about his character. Just like the Robert Altman movie before it, the MASH TV series began life as a two-hander between the characters of Hawkeye (Alan Alda) and Trapper John (Wayne Rogers). However, as time went by, it became clear Alda was the show’s breakout, while Trapper’s role gradually diminished. This is why Rogers quit MASH after the third season, while Alda took on a larger creative role.
https://screenrant.com/mash-show-hawkeye-no-gun-rule-broke-season-5/