OK
OP has suggested that the folks he was purchasing the rifle from chambered an 8mm round. The pic certainly suggests "pure" swede to me!
Here's some ammo. Two on the left are 6.5x55, the single on the left is an 8mm.

Here's my (filthy) Ljungman's chamber. Bolt has been removed.

Here is a round of 6.5x55 in the chamber.

Here is a round of 8mm Mauser. I have slid it in easily with a finger until it stopped (nothing like the push of the bolt! I dunno how deeper the bolt would wedge it in, but I doubt it could crush it all the way in)

As pure a Swede as it looks in the pics, it'd be worth a few minute's time determining what it is actually chambered in. I have doubts someone re-bored the barrel, but in that pic it is certainly a Swede barrel.
EDIT:
Sorry for the blurry pics.
OP has suggested that the folks he was purchasing the rifle from chambered an 8mm round. The pic certainly suggests "pure" swede to me!
Here's some ammo. Two on the left are 6.5x55, the single on the left is an 8mm.

Here's my (filthy) Ljungman's chamber. Bolt has been removed.

Here is a round of 6.5x55 in the chamber.

Here is a round of 8mm Mauser. I have slid it in easily with a finger until it stopped (nothing like the push of the bolt! I dunno how deeper the bolt would wedge it in, but I doubt it could crush it all the way in)

As pure a Swede as it looks in the pics, it'd be worth a few minute's time determining what it is actually chambered in. I have doubts someone re-bored the barrel, but in that pic it is certainly a Swede barrel.
EDIT:
Sorry for the blurry pics.