This is the definition of the Loading property according to the PHB:
Loading
You can fire only one piece of ammunition from a Loading weapon when you use an action, a Bonus Action, or a Reaction to fire it, regardless of the number of attacks you can normally make.
That's it. Nothing more, nothing less. No mention of needing a free hand or anything. You just attack once per turn no matter your number of attacks. But then there's Crossbow Expert:
Crossbow Expert
General Feat (Prerequisite: Level 4+, Dexterity 13+)
You gain the following benefits.
Ability Score Increase. Increase your Dexterity score by 1, to a maximum of 20.
Ignore Loading. You ignore the Loading property of the Hand Crossbow, Heavy Crossbow, and Light Crossbow (all called crossbows elsewhere in this feat). If you’re holding one of them, you can load a piece of ammunition into it even if you lack a free hand.
Firing in Melee. Being within 5 feet of an enemy doesn’t impose Disadvantage on your attack rolls with crossbows.
Dual Wielding. When you make the extra attack of the Light property, you can add your ability modifier to the damage of the extra attack if that attack is with a crossbow that has the Light property and you aren’t already adding that modifier to the damage.
And now I'm confused because besides what this feat implies, I haven't found anything that said that I needed a free hand to load a piece of ammunition in the first place.
Oh never mind I've just found it. It's in Ammunition:
Ammunition
You can use a weapon that has the Ammunition property to make a ranged attack only if you have ammunition to fire from it. The type of ammunition required is specified with the weapon’s range. Each attack expends one piece of ammunition. Drawing the ammunition is part of the attack (you need a free hand to load a one-handed weapon). After a fight, you can spend 1 minute to recover half the ammunition (round down) you used in the fight; the rest is lost.
This is the definition of the Loading property according to the PHB:
That's it. Nothing more, nothing less. No mention of needing a free hand or anything. You just attack once per turn no matter your number of attacks.
But then there's Crossbow Expert:
And now I'm confused because besides what this feat implies, I haven't found anything that said that I needed a free hand to load a piece of ammunition in the first place.
Oh never mind I've just found it. It's in Ammunition:
Next threads dive into Crossbow Expert + Equipping/Unequipping Weapons: