To get free guns in Red Dead Redemption 2, you have to finish the first Chapter. Then you need to find an NPC and help him.
As soon as you will have the opportunity to move freely through the game world, then you need to go to the South, there is the gang. Before this journey, you will need to take a potion that will restore health.
Follow the road and listen carefully, you will hear the cry of a man. Go to the Creek and come to the river, there in the grass is NPC. Walk up to him and give potion. You will be given honor points for the deed.
Now wait about a day and head to the store with a weapon in Valentine. This man is on the porch and talk with him. He will invite you into the shop, where you can choose any weapon for free.
To get free shotgun you have to complete the mission "Paying a Social Call". During the passage, notice the fireplace, it hangs over it. It also remains to be clean.
