Hello jmoore,
I have a few questions about your shooting the 7.62 in the #4.
1. I am not familiar with any official designations this version has. Can you tell me about your rifle and it's barrel and chamber?
2. Have you shot any out of the box Nato issue factory loaded or the equivalent factory loaded ammunition in your rifle?
3. If you have fired factory loaded ammo, what was it and how did your rifle perform as far as extraction. When the bolt handle is raised do the rounds pull free of the chamber normally?
4. Does you rifle have a normal or tight chamber? Is your chamber a better fit to 7.62 ammo than the typical as issued barrel of a #4 rifle to typical .303 brass? Do you get a mild or pronounced step at the pressure ring.
5. Can you tell us which powder and bullet you use. We can guess at the rest for modeling with Quick load. Any data you provide will only be used for estimation of pressure. If you don't want to post it you can PM me with the information.