Re: 6BR Norma
I doubt anyone using a straight 6BR with 28" barrel is getting 3000 fps with 107s. Most 6BR with 28" are getting around 2800-2850 absolute max. However, you can probably get 3000 if you plan on using the brass once and got a real strong action, but that is not normal or safe.
Now you can use a 6BR improved and get up around 3000-3050 with 107s if you have 30" barrel. Bill Shehane has the largest capacity 6BR (6BRBS-Baby Shehane, ain't nothing baby size about Bill if you have ever seen him). The shoulder is blown forward .200 and with 30" Hart or Kriegers, he only gets 3000-3050 with the 105-107 bullets from JLK, Berger or Sierra. I am currently building the same with a 28" and should be done by mid march so let you know. My current barrel is a 28" HV Spencer 1-8 twist and I am ordering another in 28" HV 1-12 twist for 80-85 gr flat base BR bullets.
Bob Crone has the 6mm BRX which is easier to make and does not move the shoulder as forward as much. His with 30" is in 2950 range. He shoots in F class with wife, both on US team that won world last year, plus limited 1000 yard. His and Leslie's LG and HGs are 6.5-284 improved.
Dave Kiff at PTG, makes the reamers and Bill (D & G supply at BR Central website)stocks the dies.
Caution, need to decide on which brass Norma or Lapua and have reamer cut for that brass, tight neck or not.