It kills your enemies… then slowly kills you.
When facing down the enemy you want the biggest gun available. A portable nuclear firing weapon would be the end of the opposition on the other end of the battlefield.
Well, the M65 recoilless nuclear rifle was tested by the U.S. military and received the nickname “the Davy Crockett,” due to its knock-down power. It was essentially a portable nuclear warhead but the weapon was found to have one major flaw. The nuclear fallout from the weapon didn’t out-distance the three miles it could fire.
Soldiers who fired the weapon were irradiated by their own weapon, especially if the wind was blowing back their direction.
The M65 recoilless nuclear rifle was never fielded on the battlefield, for obvious reasons. It is an interesting, and dangerous, failed experiment in military history.