I have been helping a friend of mine get some stuff together for his first "custom" savage rifle. He wants a 6.5-284 and as we were looking at a couple different sites to order a barrel I noticed that they list two different chambers... a lapua and a norma. What is the difference? I would guess neck diameters for brass neck thickness but have never seen the two different ones (but I have never looked very close at 6.5-284's because of claims of short barrel life) Can anyone help us out with a link to a print or some more info.. Also mod's -- feel free to move this if it is in the wrong place..