back when 03A3s were being rechambered to magnums was before the 300 winchester magnum came on the scene
many 06's were opened up to 308 norma
here's the ammo
http://www.selwayarmory.com/hsm-308-norma-180-gr-grand-slam-sp-box-of-20.htmlpull the bolt, measure the bolt face
call brownells get the cerro-safe
buy a no-go magnum headspace gauge (works for any belted magnum except 224 weatherby)
if everything checks out, tie it to a tire and fire it
measure all aspects of the case compared to new factory
looks like a bargain magnum