I did a Bartlein 1-9tw 5R for my SRS several years ago. At that point in time, I had to buy 300WM mags, grind the spot weld holding the spacer so it could be removed, and install a longer follower to work with the 284. I tweaked the front mag lips just a tad, and had no problems getting it to feed reliably. IIRC, I never tried any bullet lighter than the Hornady 162 AMax, using mostly Berger 180 VLDs or Hybrids. Also shot quite a few Berger 168 VLDs - everything I tried fed w/o issues.
I posted my SRS - along with both Bartlein bbls (6x47 Lapua & 284) in the for sale forum about a year ago, but didn't find anyone interested in that combination of bbls. It's still for sale though....