Edit, Ganderite posted while I was typing my reply below, and my posting is not meant to be a insult at Ganderite. It simply means I used the Hornady manual for loading my 30-30.
The latest Lyman 50th edition 30-30 rifle loading data lists 36.5 grns of 748 with a 150 RN Hornady bullet and 35.6 grns of 748 with a Hornady 170 grain RN bullet.
The loading data in the same Lyman manual for a 14 inch Contender 30-30 lists 38.5 of 748 and a 150 grain Hornady pointed soft bullet.
The 9th edition of the Hornady manual for the 30-30 lists 38.9 grains of 748 with a 150 Hornady RN and 36.5 grains of 748 with the 170 grain Hornady FP.
That being said I have loaded my 30-30 Winchester Trapper model with a 16 1/2 inch barrel with 38.0 grains of 748 and the Hornady 150 grain RN since 1982. And my primers are protruding after these cases are fired and I have cases over 30 years old I'm still using.
If the primer is protruding from the base of the case after firing it means the chamber pressure was not great enough to push the case back against the bolt face.
And if the primer is protruding it means the primer pressure on the bolt face is 400 psi or less. And the 30-30 is rated at 38,000 cup or 42,000 psi.
Loading data varies because firearms and the reloading components vary, plus the testing methods vary and this data is ball park. The data could be from a copper crusher, a pressure transducer or a strain gauge glued to the barrel.
Below my 1950 Long Branch No.4 top and my fake Jungle Carbine on the bottom.
