What three firing modes are available on the M4 service rifle?

The three firing modes available on the M4 service rifle are safe, semi-automatic, and automatic. In the safe mode, the weapon cannot be fired, protecting against accidental discharge. The semi-automatic mode allows for a single round to be fired with each pull of the trigger, requiring the shooter to release the trigger and pull it again for subsequent shots. The automatic mode, while not typically present on all M4 variants (as the M4 usually functions in semi and fully automatic), refers to the ability to fire continuously as long as the trigger is held down.

This combination of modes enhances the versatility of the rifle in various combat scenarios and training exercises. The inclusion of a "safe" mode is a crucial safety feature, ensuring that the firearm remains secure until the user is ready to engage.