On Belgian proofed guns the PV mark normaly has a Rampant Lion above it. Unless there are dual mm marks written as a fraction ie 15.8/15.4 then the 15.8 & 15.9 are most likely bore dia not choke dia. If the bbl is just stamped Choke 15.8 then this means the bore dia is 15.8mm (.622") & is choked, but amount not specified. 15.9mm = .626". Nominal dia for 20ga = .615" so these are slightly overbore.

Miller/TN
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