Swede 94 Carbine = Gallery Rifle?

[Crimper-D]

I have a little Swedish Cavelry Carbine that has never been able to hit the side of a barn at 100yds - even with the addition of the high front sight avilable as an aftermarket addon.
Turns out from an aiterpretation of the stock disk that it was issued as a Gallery practice rifle ="B" for "Belfsvapen"
Another source made reference to the gallery guns used by the Swede military having a different twist rate than the issue weapons in order to stabelize the little lightweight gallery loads.
Mine shoots the gallery ammo into a quarter sized group at 20 yds - offhand.
My question is what twist rate is in the barrel of this thing, and how can I get it to stabelize the 140gr bullets?

 

[TexasVet]

Finding the twist rate is easy, Run in a cleaning rod with a non-rotating head, mark it in line with the front sight and even with the muzzle. Pull it out, letting it turn with the rifling, until that mark is in line with the sight again. Measure the distance from the muzzle to the mark and that gives you the X in 1 turn in X inches. That's the twist rate.
If it was rebarelled for the gallery rounds, it may not be able at all to stabilize heavier bullets.