I would have to respectively disagree with your interpretation of the SAMMI chamber drawing. Free bore is the straight bore that is the same diameter from the neck chamber to the point where the lead angle starts. the lead angle will determine how much more Jump you will get depending on the bullet ojive.
On the 300 WSM this straight bore is called Free bore and has nothing to do with the lead angle. This dimension on the SAMMI drawings is .189. SAMMI sets this dimension based on magazine length and allows you to utilize a certain amount of free bore depending on which bullet is used to control pressure. It is also the dimension reamer manufactures HAVE to use if it is a SAMMI spec. reamer.
Bullet selection and seating depth will certainly have an effect on the distance the bullet will travel before it contacts the lead angle. but the free bore is set by the SAMMI drawing for the reamer makers and must be adhered to if it is SAMMI spec.
So the free bore is set BY SAMMI and altered by the seating depth of different bullet shapes. .036 sounds about right for loaded ammo unless you touch the lands like many do and then you have no usable free bore even though it is built in by SAMMI. Or you have some people that want more bullet jump for velocity and pressure control and they may have up to .100 + thousandths jump by seating deeper
but they still have the free bore that was built in by SAMMI.
Also in order to use all of the SAMMI free bore, you would have to seat the bullet deep enough in the case so that the bullet ojive would be at or near the case mouth depending on the bullet shape. this is normally never done.
J E CUSTOM