Are we talking about competition rifles or hunting rifles ?
For me, personally, anything which is "non-BR or F-class". Even for my PRS rifles, I just don't benefit - AT ALL OR IN ANY WAY - from having sub-quarter MOA vs. being satisfied by sub-half MOA. Many of my load dev groups for my custom rifles ARE sub-quarter, but even my anti-nodes would be sub-half, any of which will yield the same score at any PRS match in the country - and obviously would do the job hunting as well, and even if those results spread from 1/4-1/2 in custom barrels to 1/2-3/4 in factory drain pipes, they'll all do what I need for hunting... so I party on with a easy, quick, inexpensive, and non-complex load dev process, and don't let myself chase rabbits which won't get me fed.
I feel for the OP... I had very much the same issue with my Savage. All that time and money spent on test loads... none of which shot better... or equal... than FGMM?!?!
I usually discourage folks from trying to chase factory ammo - for several reasons, including reloads = lower cost, and generally, superceding factory ammo with reloads is a very simple process, but, 308win FGMM offers very specific opportunities:
We have info out there about FGMM, and unlike many factory ammo offerings, we have the rare opportunity to replicate it, because it is known to use cannister powders which are available to civilian reloaders. We know the bullet, and we know it has been loaded with IMR4064 and with RL-15 (maybe others, but certainly with these two). The evolution of M118 through "Mexican Match" ammo, to another designation - I think M852? - then eventually back to M118LR also documents the same. So if I put 43.5-43.8grn of 4064 under a 168 SMK and it doesn't shoot, but FGMM factory ammo DOES shoot in my rifle, then I've eliminated the rifle/barrel, the bullet, the powder, and the marksman as the faulty attribute of the process, and have successfully deduced that only the reloading process could be the broken attribute. So while I might not USUALLY like the idea of chasing factory ammo with reloads (if I'm building a NASCAR stock car, I don't try to replicate a Ford Fusion factory model), but FGMM offers a unique barometer for our reloading process performance. At the end of the day, it's still machine manufactured, mass-production ammo, so a good process with a lot of hand-to-product connection always should at least meet their performance, if we fall short, then we fix the loading process.