I have Brescia proofed Bernardelli and Armi San Marco hammer guns with a crown over Rampant Lion proof house mark.
Both Wirnsberger and "The Italian Gun" show the Rampant Lion as the Brescia proof house symbol.
The OP's gun shows a much more finely rendered Rampant Lion than the later National Proof Rules mark.
I do not have any difinative proof that this is a Brescia gun.