From NRA:

Ammunition exports to the United States are only a small percentage of the GDP of the Russian Federation, but Russian origin ammo makes up a large part of the American ammunition supply. American gun owners were already suffering from a market where demand was exceeding available supply. This new move by the Biden Administration will severely worsen the present supply problems.

I guess the Biden administration killed two birds with one stone here, they hurt Russian exporters, and American gun owners, two groups the Democrats hate. Let’s go Brandon!