I, just a few weeks ago, completed a conversion from SA to LA on a 6.5mm x .284. 7mm bullets won't be much shorter than 6.5mm bullets. LA allows the throat to be lengthened so bullets can be seated so no bearing surface is below the neck in the case (the boat tail may be). Allows for the use of case capacity for powder, not bullet. Several years ago I saw a Rem. 722 with an extended mag box, very nicely done. One may consider a Wyatts' extended mag box on a short action if it will allow enough length (3.060"). All the above is in ref to Rem. 700 actions. Montana Rifle Co.s' short action has a std. mag box length of 3 1/8", ideal (IMO) for any cartridge based on the .284 Win. case.