I have the same combo but I throated mine out. I shoot the 147s almost exclusively. Easy to tune and great bc. I don't know about donuts in the 6.5 brass yet because I bought adg already formed. If you made brass from 7 saum then I would check for the donuts. They don't form on a consistent basis and can definitely give eratic grouping. I have a Wyatt's long box in mine and the 147s fit real nice and are not in the neck shoulder junction. I have about .030 of more room in the box left. Hope this helps. It's a real nice cartridge.
Shep