One of the reasons I was fairly quick to jump on this firearm is that the 10.15x61R Jarmann cartridge is 1) easy to form from .348 Win cases, and, (another reason why I let it get in my head that it was a Husqvarna) 2) a Swedish military cartridge.
So I have fireformed a case and stuck a 200-grain, (originally .425"), jacketed bullet 'squoze' down to 0.410" in the case to make a 'dummy' cartridge.
I slugged the bore, and it has 7 lands and 7 grooves, which makes measuring the bore dimension, (land-to-land), or the groove dimension, (groove-to-groove), tough. Land-to-groove dimension is 0.406". As I thought about it, that dimension should be about right for a jacketed bullet's diameter. Add a thousandth or two for a cast lead bullet.
The case has a measured capacity of 87.0 grains of water. You will all be surprised to hear that I paper-whipped those numbers in QuickLOAD (QL).

Here are the result of that paper-whipping.
200 grain bullet
26" barrel
Max allowed pressure - 25,000 PSI (Fairly conservative, but y'all know I don't like to beat up old guns. That said, this is not that old a gun. I think between 1915 and 1925. Non-damascus shotgun barrel.)
60.2 grains of Accurate 2495 yields a muzzle velocity of 2450 f/s which in turn produces 2675 ft-lbs of muzzle energy. Not bad.
With the sights 0.75" above the mid-line of the bore, sighted in at 125 yd, the rifle is 1" high at 75 yd and 6" low at 200 yd retaining 1280 ft-lbs of energy. Not bad for a bullet with a G1 BC of 0.205.
I'm kinda liking that load - 200-grain bullet, 2450 f/s MV. Easy on the gun. Easy on my shoulder. .40 caliber hole. Moose-lethal out to 200 yd. Tough to beat for what it is.
I have to get a bullet resizing die in about 0.406". I
might be willing to shoot 0.410" CAST bullets with a gas check from this rifle. Gotta come up with some reloading dies too. I hate to part with $135+S&H for factory-new dies, but may have to. I don't know if I could find a reamer for cutting resizing die.
Gotta come up with a bullet I am OK shooting through this bore before I shoot it, but it shouldn't take me too long.
Paul