mick,
do not be a defeatist!
in the day, the average 10 year old could understand and do this because it is really quite simple.
1) for best accuracy the patched bullet should be a good fit in the bore. this aligns the centre of mass of the bullet with the axis of the bore. as the bullet leaves the muzzle it does it in a smooth uninterrupted flow. just slight friction is optimum.
2) know your bore diameter in the breech end.. pin gauges are ideal, but cerrosafe done correctly is also good.
some friction is ideal, as it stops bullets sliding of their own free will, particularly when breech seating.
3) know the thickness of 2 wraps of paper. this can be done as mentioned above, by wrapping a bolt or whatever and measuring.
ideally 2 thicknesses of paper are equal to or less than depth of rifling.
4) subtract the thickness of 2 wraps, established from wrapping the bolt, from the bore diameter and you have the diameter to order the mould.

this is homework.
too many guys try to avoid it and end up going around in circles and disappear up their own arses.

a bullet with paralell sides can be breech seated easily.
it can be loaded in cases fired in a greaser chamber, but they need severe neck sizing to get a finger seat fit. 

go by arnie's recommended bullet length.

easiest way to not size brass for bore diameter pp bullets fixed ammo is to make the front of the bullet as above, and the rear of it patching to a diameter that slip fits into a fired case neck.
not a tapered bullet, but 2 diameter.
if arnie's mould maker cannot help you, contact kal or brooks on this and give them measurements attatched to a drawing. 
understand this and never look back.
keep safe,
bruce.   

so mick,
how much does 2 wraps of your paper add to a diameter?
what is your bore diameter?
subtract theformer from the latter, and there is your cast bullet diameter.
try this with wet patching and dry patching, and let us know both  measurements.
keep safe,
bruce.

that is good mick.
never use the word krieger in the same sentence as sako.
that is not the first sako barrel not up to standard.
krieger's stated measurements are usually pretty correct.
your thickness for that paper reflect that of others.
you are ready to go.
keep safe,
bruce.