Re: 6.5 X 284 WIN or 6.5 X 284 Norma?
There is actually more than 1 kind of Norma reamer. The standard reamer with a .501 web and the norma match with a .499" web. I use the match chanber with Lapua brass to try and keep the pockets tighter, longer. The neck on the win chamber is .301", the
Norma and Norma match is .2975/.2972 tapered or strait depending on which you want.
The throats. The standard Norma and Norma match reamers are set up to put the start of the boattail at the shoulder/neck junction. Depending on the bullets you use, this gives and OAL of 3.000 to 3.035" using Sierra 142SMK's. If you want to feed from a magazine, it best be a long magazine, and you'll need to have the feed rails opened somewhat to accomodate the wider web. The bolt face will also have to have a bevel cut to allow the rebate rim to snap in without contacting the case body.
The easiest and most user friendly reamer I've used is the Norma Match by Dave Kiff at Pacific Precision. He has them in stock generally, and they're only like $138 with two pilots.
I personally use a Norma match with a .4985" web and a throat shortened by .1". Also, I use a slight tapered nack with .003" difference from mouth to shoulder. A strat neck would be just as good, if not better I think, as it may help minimize the doughnuts. This chamber allows for the tight primer pockets and I can chase the lands longer before a set back is required. As far as accuarcy, I haven't seen a difference, and with the powder I use, H4350 or 4831, the load density is only betwen 85 to 90% so having the bullet deeper in the ase hasn't hurt anything.
Hope this helps some.