Re: 300 rum o.a.l.
The max length that will fit in the mag box, or shorter if the bullet contacts the rifling, which is not likely. Mine contacts the rifling at about 3.830 with a 200gr Accubond but my max length is 3.660-3.665 as anything longer will not fit in the mag box. BTW, the 200gr Accubond with about ~90gr Retumbo shoots awesome when seated to fit the box at 3.660". Max load is slightly higher though.