I don't reload for the 6.5X54MS but did learn a few things while researching available loads. Pardon me if you are already aware of this stuff.
First is that the 1903's have bores that are larger than the american standard. The bullets in the loaded ammo that I buy measures .266, not .264 like most available as 6.5mm for reloading.
Second is that the twist rate is designed for the heavier 156 to 160 grain bullets traditionally used. Also feeding from the magazine may not be smooth with lighter, shorter bullets.
Hope this helps. I have one and they are handy and pleasant to shoot.
