Long Range Hunting Forum

For my 300 WM, my load has been 77.5 gr of H1000 behind a 208 ELD-M. Now that my rifle is glass bedded, it is shooting better. But I cannot get any more Hornady bullets. So I thought I bought 2 boxes of 210 gr. Nosler Acubond Long range (ABLR). Only 2 grain difference in weight, but the ABLR has an even higher BC of 730. Hornady is 690. So, I loaded up some using the exact same load and exact same seating depth. Cartridge Base To Ogive measurement is 3.920 on both using my comparator.

First pic is Hornady 208 Gr with virtually 0 neck tension. It is a 5-shot group and is the best I have ever shot with this rifle. The second pic is same load, same bullet with about .002-003 neck tension. Again, it is a good sub-moa group. The 3rd pic is the exact same load, same neck tension (.002) and same seating depth. It is WAY all over the place. Another group was also as bad.

I need to know what to do? Do I experiment with charge or seating depth? Since I am measuring to the ogive, why would seating depth be different? I would appreciate any input or suggestions. Thanks