OK now you have pinned it down.
You have no need at this weight limit to worry about fluting or anything. Fclass is not BR but is an NRA sanctioned match. Also this puts you in the Open class. they have two classes, FT-R (223 and 308 only) and Open (any other caliber)
Now most of the BRs in Fclass are either the Dasher or the BRX with the edge probably to the BRX. The straight BR can compete but is not the round of choice and gives up a little MV compared to the improved models.
With the straight BR you are looking at the 105-107 gr bullets at 2800-2850 as compared to 2950 to 3050 in the improved models. That equates to little more wind drift in particular for the straight BR.
The BRX uses standard BR dies and now several die mftrs have come out with Dasher dies.
Another option is the no neck turn 6x47 (6.5x47 necked down). Stock dies are out and runs the 105-107 gr bullets 3100-3200.
Either way order your own no neck turn reamer and go/no go guages ($200 for all) and it will last you a lifetime. Look at www.6mmbr.com
for discussions on what freebore or call Dave Kiff at Pacific Tool and Guage (PTG) and order your reamer from him.
It is relatively easy to fireform any of the cartridges and even in matches. You simply buy an exanding mandrel ($25 from Sinclair or K&M), neck up to the next size caliber (25) and then neck size down leaving a small false shoulder where it is slightly tight chambering. Use a little lube(truecote, or lube wax) on the shoulders when firing and perfect fireforming. Articles on how to at 6mmbr.
I am shooting a BRDX (BR Ack Imp) that has shot 105 FB bullets 3130 with extreme accuracy. I am rechambering it now to a no neck turn .272 and shorter throat for the VLD bullets.
go to long range target shooting forum for detailed info on Fclass, guns, cartridges etc. Only thing is this is where the top dogs in Fclass hang out such as the US Fclass team is and they normally shoot the 6.5-284 as it is flatter yet and a barrel only lasts 800-1200 rds compared to 2000-4000 for BR derivatives.
I would go with the BRX or 6-47. Go to the local F class matches in NJ, PA and see what type rigs everyone is shooting first.