If F class, the RB RP You cannot shoot faster than the target puller. So RB LP is meaningless and you have plenty of time.
30" match grade barrel. Set it up without the nut IMO. Match thick recoil lug
HV taper to .950 IMO, IF no nut. Otherwise you are stuck to factory breech dimensions.
IMO I would go with Dasher or BRX also. 3000 fps vs 2850 Read about both on www.6mmbr.com
Order your own reamer no matter what. .100 freebore for the 105 gr bullets. I suggest Dave Kiff at Pacific Tool and Guage (PTG) $150 plus another $50 for go/no-go guages.
Go to Harrels for dies IF you go with the standard BR. Cheaper and best. check on BR central for their contact info. They might have Dasher dies also.
Stock take your pick, but you will be in the Open class so if not a 3" foreend , go to www.sinclairintl.com
and buy their 3" foreend adapter.
They also sell a nice super light F class rest.
Have Fred at SSS true and time your action. In fact call him first. He stocks normally timed and trued target actions for around $500 ready to go, that is the best deal as his wait time to get an action trued is one year now.
NO muzzle brakes, waste of money in the 6br family and you cannot use them in fclass.
Weight limit is 22 lbs limit.
Go with a 20 MOA tapered base. Farrel or burris dovetail and Burris signature rings with 20 MOA inserts.
Sightron 8-32x scope for best deal money wise ($800). Buy a Bulls Eyze 3x screw in booster $125 or the NF BR (not NXS) model 12-42X
RL15 or Varget powder, CCI 450 primers, either berger 108 or 108 and 105 AMAX.