Re: .223/5.56 for F T/R class?
2010 @ the BCRA Int'l Rifle Championships (4 days of 300, 400, 500 & 600 metes) 1st F/TR was running a stock Savage 12 F/TR 30" 1-7" tw, B82BTs over N150, Lapua cases, Rem 7-1/2 primers at a MV of about 2850fps. 2nd F/TR was running S80MKs at a similar speed.
When people say slower powders for a .223 Rem, they are usually talking RE-15, N150, N540, N550. I've heard *rumors* of one person running RE-17 - maybe. This is considered 'slow' in comparison to stuff like BLC2, H4895, Varget (depending on lot), N135, TAC, etc. Not much of a spread, but then its a pretty dinky cartridge...
One of the tricky parts is getting a long throated chamber to allow you to seat the bullets waaay out there. Sadly the gun I have has more of a gas-gun (Wylde) chamber - a good compromise for say, NRA High Power XTC where you may alternate mag-fed on one stage for Rapids and single load on another for Slow-fire Prone. Not so good for a single-load only bolt gun - the long 80+ and 90gn bullets end up seated too deep in the case.