CZ452 rimfire rifle receiver, if it's a forging they would use billet steel.

If they're going to hot work (forge) the receiver to its shape, there's no reason for them to use steel with a good surface finish, and pay the extra for that work to be done to the steel, when the forging process creates an entirely new surface on the steel.
Many rimfire bolt action rifles' receivers are machined out of steel tubing. Some semi-auto .22RF receivers are are plastic. As in Remington semi-auto .22RF the bolt actually works in the plastic stock and they have a stamped sheet metal cover to make it look like a receiver.