Yep makes sense. Great advise and tips for all. Building a dedicated f class gun is pretty clear cut. Problem is I don't want that really. Looking to balance what I read in the rather sections with folks who do it for competition.
The clarification on barrel length really helps cause this forum is filled with guys hitting 1/4 groups at 1000 just like you said. Your explanation really helped me reconcile all that noise.
Let me tell you a story about that. Before I start, I will say that I have read (and chuckled at) countless claims and posts about someone being able to shoot sub-MOA at 1000 yards with any .308 rifle; I especially guffaw when it's an 18-24 inch rifle shooting factory or military ammo. I do remember a few years back posting here that I had never shot sub-MOA at 1000 yards, and some of the braggards offered to teach me how to do that with their "hammers of Thor" and other assorted tactical sticks shooting surplus ammo. At that point, I knew it was a waste of time discussing it further.
Setting your expectations ahead of time is a good thing. Your Tactical/F-TR boom-stick will be fine to play at 300 and maybe even up to 600, though do not expect to be very competitive when the wind blows. As for 1000 yards, don't even go there with that FGMM ammo.
Now for the story.
Talking about shooting sub-MOA at 1000 yards, to an F-class competitor, that represents a clean; all 10s and Xs since the 10-ring is 10 inches across or right about 1 MOA. At the recently-concluded Nationals, with some of the best shooters in the World, using rifles and ammo that far exceed the precision and muzzle velocity of any tactical rifle with FGMM or M118-LR, there were only five cleans when shooting 15 rounds and one clean on the Thursday shooting 20 rounds. There were about 200 shooters, shooting six 15-round matches and two 20-round matches for that week, all at 1000 yards. I do not believe there was a single clean at 1000 yards during the Worlds championship that followed the Nationals.
The 20-shot clean occurred on Thursday morning at the same time I actually shot a personal best of 199-7, dropping a single point. This was interesting because I took my customary 5 sighters from a clean barrel with sighter 4 being a 10 and sighter 5 an X. Then I went for record and thankfully shot a 10. When I got to round 16 for record, my shooting hand was shaking so bad, I fumbled with the cartridge, but managed to get it in the chamber. I dropped that shot as it went into the 9-ring just outside the 10 at 9 o'clock. I almost called a challenge and then remembered they were only 3000 feet closer to the target and it might take too much time, losing me the conditions that I had been riding, and possibly even getting me out of position. So I just kept on trucking and now with a point down, I was much calmer and didn't drop another one. I came in seventh for that match as four other guys and one gal shot 199s with a higher X-count than mine.
I almost shot sub-MOA at 1000 yards that morning; 17 consecutive shots in the 10- and X- ring (including the last two sighters.) And this is with a 42X scope, 32 inch medium-heavy Palma Krieger barrel, Sinclair Gen 3 bipod, a one point five ounce trigger and shooting bullets that are far superior to 168 or 175 SMKs in a load specifically tailored for the rifle. If it had been a 15 round match, that would have been a clean (sub-MOA), but it was a 20-round match so I'm still in search of that elusive sub-MOA at 1000 yards with a .308.
I still laugh at claims of sub-MOA shooting at 1000 yards with a .308.