use your cleaning rod, assuming it rotates, and starting at the muzzle using a tight oils patch count the revolutions the rod makes as you push it thru then use simple math to figure it out. Hint put a piece of masking tape on the rod so you can see how many times the rod revolves.
Thanks for the reply. I haven`t tried this yet as I`ve seen some places that give an odd number like 1/9.25 and didn`t want to be off. I was wondering if there was some official version. I`m looking to reload for it, but trying to find what bullets will work with what powder to cut the recoil while addressing the twist. I want to shoot it, but want to cut the recoil the stock from splitting. Probably unlikely, but don`t want to take the chance with something I can`t replace. I have the original and want to keep it in good shape, but spent the money to get a later 41? laminate stock to shoot with. Don`t want to damage it either. Looks like you suggestion will have to do.
I would think it would be the standard 1 in 9 twist rate. I doubt they made special barrels with any different twist rate. I don't think you should have any problem with the bullets that are standard for reloading 8mm. If you are that worried about recoil get some CAST bullets and load them up with 16-18 grains of 2400. Makes a fun low recoil load.