I think the neatest thing are the loaded indicators, if that is what they are. My 1st guess was that it was A.V. Lebeda sourced but it doesn't have the stepped locks. So with the dragons on the hammers I would lean toward Herzberg but it could have been sourced from Austria. I would guess it to be a 15mm, thereabouts.

Kind Regards,

Raimey
rse