Help me date this Browning Auto 5

[Salibas007]

I got this browning Auto 5 from an estate sale and I’m having a hard time dating it.

This is what the bottom plate of the receiver has stamped on it

It comes with a 32” bbl 2 3/4” shells stamped made in Belgium

Any help would be appreciated

 

[cooter303]

the 1m indicates 1961 manufacture.

 

[Salibas007]

Many thanks