Bulgarians have a lot of resources to produce those types of weapons and ammos.
Unfortunately the politicians are lying in plain sight and are selling through contractors.
They are saying to the people “we don’t sell” and they then brag that they are actually selling in front of European politicians.
https://www.dw.com/en/how-bulgaria-secretly-armed-ukraine-with-nato-weapons-deliveries/a-64478423
And this is not related to the previous government only. Maybe even the current one is doing the same thing.