Martini 577-450 Sporting Rifle - Help with proof marks

Hello All,

This forum is for "single shots" and "combination guns" - well I just bought one of each. (separate posts)

This is the first one. A Martini 577-450. First one of these I've ever owned.

Here are the specs of this rifle ....

28-3/4" Bbl - 14-1/4" LOP - 7 lbs 6 oz - Trap Butt - 2-Leaf Express Sight - Moon Flip-Over Front Sight -

I am interested in what all the markings mean .... best as I can describe, marks are as follows ...

"T.BLAND" on action - Bbl stamps "Crown / BP ? ?" .... "450" "1323" "45" "2054" "JG" "11.3" "*/AE" " "PJG" "EL" "JJH" - Assy No. 43 on forend, bbl, and action.

Not sure about the proof marks where the barrel joins the action ... looks like a crown over an italic BP but can't tell.

I don't know a thing about these, so any info would be appreciated ....

By the way, it came with a box of Kynoch Factory ammo, and this neat little insert for 45 long Colt and a full box of ammo.