If money and availability were no concern, then I'd be tempted to try out the APA bottom metal. A lot of guys really like the design of that unit, and it will take AICS or AW mags.
If you're running the 105AM, then an OAL of about 2.820" puts the base of the bullet's bearing surface right at the base of the .243AI's case neck, so a mag box that measures 2.840" would be plenty.
Without having the 140gr Berger VLD or Hybrid in my hands, it looks like, based on calculations, an OAL of 2.977" would put the base of the bearing surface of the 140 VLD at the base of the neck on the .260 Rem. That means that if you're using AICS mags, you'll want to remove the reinforcing plate in order to get enough space for that 2.977" OAL. You'd have to throat accordingly, of course.
ADL isn't a bad way to roll for a hunting rifle, but it's nice to have the M5-style BM and AICS mags for a rifle that is used for both hunting and a lot of steel/paper.
