Ah ... I (finally) see!

Reference to 6.5CM in a forum that deals with shoulder rifles usually means the millimetre measurement Creedmoor variant. Apart from having bit of fun, I assume you're making a gentle point re sloppy abbreviations here. I'm not too keen on this shorthand designation myself, but it's with us permanently now I'd reckon. If you're into firearms and handloading, you've just got to have a two or three alpha catchy name - 6ARC, various PRCs and suchlike, not to mention Norma URP, Alliant's TZ and more. Reminds me of my long ago childhood glued to the black and white TV and Virgil Tracy's 'Eff Ayy Bee' radio response in
Thunderbirds.
What does FAB stand for in Thunderbirds?
Ahem, as obviously you know, thought that 6.5 bullets represent the same in millimetres is far from the fact. Just a lazy convention.
More like 6.72 mm. Not far off 7mm (true as in the .270 etc), but nowhere near the bulk of the 7mm chamberings that actually shoot a bullet of 7.2mm. There is quite some history behind that.
I'm not sure what the 6.5 Grendel really has to offer stalkers here. Yes it can just make the numbers for large deer, but is not a flat shooter like faster things with a bit more powder behind them, at stalking distances. Perhaps mildly interesting, and experimentally for target shooting where it might replicate the ballistics of a .308 with far less powder and recoil, even similar barrel life. Which is certainly interesting. BTW CZ don't do the nice little 527 in Grendel anymore, so I think that maybe a Howa mini action is all that you might still be able to get for it, off the shelf.
Of course the venerable 6.5x55 Swede does actually shoot 6.71 mm bullets also, with potentially a little more grunt than the 6.5 Creedmoor. Endless discussions around that.
As with the 6mm CM, which is technically superior to the old .243 particularly with it's better twist rate. But I can't see it gaining much traction. Nobody seems to be much interested in it hereabouts.
The PRC cartridges however do interest me. Are they becoming a thing yet on the UK target shooting scene ?
Its all a bit empirical.
FAB, an invention of Gerry Anderson. Some think that it might have meant "Fully Audible Broadcast. Tosh. It was just "fabulous". And always was, every time. They always had perfect comms.
Nowadays properly might be responded to as READABLE, (same number of syllables, but I do like FAB, if you didn't want to get into strength codes etc. where it might be a 4.
CLEAR The quality of your transmission is excellent.
GOOD Your signal strength is good. READABLE The quality of your transmission is satisfactory.
WEAK Your signal strength is weak. UNREADABLE The quality of your transmission is so bad that I cannot read you.
VERY WEAK Your signal strength is very weak. DISTORTED Having trouble reading you due to interference.
FADING At times your signal strength fades to such an extent that continuous reception cannot be relied upon. WITH INTERFERENCE Having trouble reading you due to interference.
INTERMITTENT Having trouble reading you because your signal is intermittent.