You aren't going to find many rifles that are throated so that you can jam the bullets in the rifling when seated to SAAMI COAL. Most 308-class magazines are gonna limit seating depth to a max of around 2.825-2.850 or so. Work around a round that you can fit in the magazine, and tune with powder charges to start. You can then fine tune with seating depth once you are happy with the powder charge. I would recommend Varget or RL15 to start with as far as powder goes.
Happy to help,
Kevin
Bookmarks