The kanji and the word are exactly the same. That means they share meanings as well.

弾 refers to bullets and other projectiles, including artillery shells and BB pellets.

Bullets used to be round, so maybe that's why this vocab shares a たま reading with other words you've learned for round things, like 玉 and 球. Remember those?

If not, just imagine a bullet being grabbed out of the air by Tamara (たま), the local ball girl. She heard there was a たま and mistook it for a ball, and now her hand is kinda messed up. Try not to repeat her mistake.