Jimmyjazz,
Pictured below is the difference between an action made by CG and one made by HVA.
First, you need to know that HVA did not produce M/94/96/38 actions variants before 1941.
Before that, all their sproting repeaters were made on Carl Gustav made M/94 actions (the M/94 have a bent bolt handle, while the M/96 have a straight bolt handle). Since your rifles was made in 1931, then, there is no doubt the action is one made at Carl Gustav.
This picture shows a M/649 (top) and a M/46 (bottom) - see that the m/46 have crowns stamped on the bolt release lever;
These are proof / acceptation marks and from the position if it, we can say they are from the CG factory - as they stand "upright" - also note that the M/649 does not have the crowns stamped on it (except some thiny parts).
The proof / acceptation marks, on a M/46, will be found on the bolt release lever, the bolt shroud, the rear of the cocking piece projection, on the trigger guard plate, above the floorplate, on the floorplate, below the bolt handle, at the bolt end left side of the extractor, on the extractor collet-ring, on the follower.
As you can see on the picture, the CG-made receivers don't have HVA rollstamp on the front receiver ring, it was left virgin.
The M/46, were made from 1927 to 1937 (S/N Range 501 to 14006) and are easy to recognize as they have a round pistol grip while the M/46B (9.3X57) and the M/46A (6.5X55), both made from 1942 to 1945 have a black pistol grip cap.
Below, it's the same part, but made by HVA (from a M/38)
see how the crowns are "bent" or "on a slope" or "angled", this is the HVA proof / acceptation mark up to end of WWII.
Now, the 9.3X62 caliber was introduced in HVA's line in 1941 as the model 46AN, but they are very rare - only 227 were made on the M/38 action (with thumb cut-out), and the barrels are marked "ANTIOXID".
The M/46, which were only chambered in 9.3X57 were marked as below;
- when you see 9.3MM, this automatically means you have a 9.3X57 chambering - but, it could have been rechambered, like yours, then, usually, the gunsmith adds a X62 at the end.
When they chambered their rifles in 9.3X62, they decided to add the complete name to avoid confusion;
Hope that helps you in your quest of knowing what you have.