Actually the ground-off Coat of Arms was done by the Argentine military itself... a few had been sold to Chile, and some Chileans shot a few Argentinians, and were captured, and the soldiers were very upset that they were being shot at by their own guns (which at the time was the finest military rifle in the world), and so from then on all the rifles sold had their Coat of Arms ground off... mine is the same way.
The book explains all the symbols... the shaking hands for instance is a symbol of the uniting of the southern provinces. It is found in seven locations. MB in script is the test-firing mark, and there is also a Frigian Cap, Rising Sun, Oval, Anchor, Half-Moon, Four Point Star, Buckle, Five Point Star, Cross, Flattened Oval, Triangle, a different Four Point Star, and a Circle.
But too bad about the shortened barrel... ruined for collecting purposes but still cool to own. I paid $650 for mine last year, pretty much in perfect condition, but lightly fired.
K