IMHO: This could be a real 'School Rifle' (shortened rifle adapted for bayonet and sling). The second cartouche makes the stock alteration more convincing.

The front sight blade and pin look kind of funky.

The most significant thing to look at is probably the front barrel-band/bayonet lug.

Has the barrel-band been stretched on an arbor to fit the larger barrel contour?

How is the bayonet lug shaped?

The photos do not show detail of front band.