Don't know if it's Bulgarian but surely it's postwar in any case !
I don't recognise the ink stamp, but it looks Bulgarian to me.
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It is definitely Bulgarian, I've had several in my collection, And one had the same exact horizontal stitch pattern in the liner "walls", Rather than the normal vertical pattern. Blue/purple ink is another "sign" as most all Bulgarian ushankas have this same color for the inside stamps.
They look close but best way to tell is the sewing pattern inside.
A Soviet 40's era one will most always have 4 sets of 3 lines crossing each other with a distinct diamond shape in the middle, Or 4 sets of 2 lines crossing each other with a diamond shape in the middle. And vertical sewing pattern on the liners "wall" ..... Even with that though you still need to be careful and post pics for experts to examine.