I also have both the 12 FV 6.5mm CM and the 12 FV .223.
I also have a 12 LRP in 6.5mm CM and, to be honest, the 12 FV shoots almost as accurately for a lot less money.
However, I am more consistent with the 12 LRP, at least with the factory stocks. The HS-Precision stock on the 12 LRP is much more stable then the hidden mag factory stock on the 12 FV. I could feel the 12 FV stock flex with the 6.5mm Creedmoor and eventually changed the stock to an Oryx chassis and got about a 10% improvement in accuracy.

For the 12 FV 6.5mm Creedmoor, the 140 ELD-M Hornady and the 147 ELD-M Hornady shoot very well.
I was really surpriesed with the accuracy of the 143 ELD-X (a good choice if you want a hunting round).
The 130 ELD-M also surprised me with its accuracy.
The Hornady American Whitetail 129 gr Interlok shot OK, but the groups were about 10% larger than the 143 ELD-X ammo.

I find the 140 Berger VLD Targets shoot better in my hand loads when I load them out further than in the factory ammo.
I haven't tried any other factory ammo because my hand loads shoot so much more accurately.

For the .223:
Federal Premium Gold Medal Match 69 grain Sierra SMKs shoot well in my 12 FV, slightly better than the Nosler or Norma match ammo.
My shooting buddy also has a 12 FV .223 and his likes Nosler CC 69 gr match ammo slightly better than the Sierras.
After years of measuring accuracy in multiple rifles, I am not surprised that individual barrels have preferences for particular ammos, bullets types, or bullet weights so I start with the premise that a new rifle will tell me what it likes regardless of what anyone else tells me.

Also I tried Federal Premium Gold Medal Match 77 SMKs and, although they aren't supposed to stabilize in a 1:9 twist, they shoot surprisingly well, just about the same as the 69 FPGGM SMKs.
I also switched the factory stock to an Oryx chassis, primarily because I found it too hard to get my long O.A.L. heavy bullets into the hidden magazine on the factory 12 FV. The .223 didn't flex the stock like the 6.5mm but my old fingers just couldn't load the longer rounds easily.
You won't have that problem with factory rounds because the O.A.L.s are just under SAAMI recommendations. That is about 0.1 inches or more shorter than the O.A.Ls that I am hand loading to achieve a jump of around 0.020 in my .223. But it has over 2000 rounds through the barrel and the chamber has eroded a bit.

My 12 FV .223 shoots better with heavy bullets than lighter ones.
The Sierra 52 gr SMKs, Berger 52 FBs and 53 gr SMKs, which shoot best in my other 1:9 twist, don't shoot quite as accurately in my 12 FV as the heavier bullets.

IMO the cheap ammos just don't measure up to the good match ammos, even though they may be a lot cheaper.
I am sort of an accuracy nut so, to me, the match ammos are worth the extra money.

Enjoy your 12 FVs. Mine are a joy to shoot and I marvel that rifles that cost so little shoot so well.