I think the Jap A5 barrels did fit the Belgian guns. Now remember, the new A5 being made now is a different animal and those Do Not interchange. Totally different guns. Many years ago Browning made the older A5 in Japan for a while after making the Belgian ones. Those guns were the same I think.. I know the Belgian guns had a softer steel barrel, not recommended for use with steel shot. The guys would buy Jap barrels to put on their duck hunting guns as the Jap barrels were steel rated. Browning confused folks by calling both the old and now new guns A5. Did the same thing by naming their newer Winchester O/U a 101. Not the same gun as the old one. Should have picked a different model designate. JMO
Clear as mud, right! Colonel