Would be interesting for both @MarinePMI and @Laurie to weigh in
I can speak from personal experience of shooting 308 Win 175gn SMK handloads from a 24-inch barrel police-military rifle at up to 1,000. (Early days of the F/TR class maybe 15 years ago). That ammunition would have been ballistically pretty close to M118LR, maybe a touch lower MVs.
It shot very well (relatively, but nothing like the standards 308 F/TR would soon achieve in long-barrel custom built competition rifles) to 800 yards. 900 became decidedly 'iffy'; 1,000 yards in all but a flat calm 'sucked' to use an Americanism.
Litz gives the 175 SMK an average G7 BC of 0.243. Run it at the M118LR's nominal 2580 fps at 1,000 ft asl and 59-deg F air temperature, and ballistic solvers say the bullet is travelling at 1,119 fps at 1,000 yards - which is unfortunate as the speed of sound is c. 1125 fps. I set 1,000 ft altitude on the solver as my first outing at this distance with this rifle and ammo was in 'spring' (Ha! Ha!) on the West Atholl RC Glen Tilt Range above Blair Atholl in Perthshire. With a strong and switching NE angled headwind and rain squalls that doubled or tripled peak wind speeds every few minutes, it became very difficult to keep bullets on the frame let alone anywhere near the target centre. Almost certainly with bullets bracketing the sound barrier, I was getting very variable performance over the last few yards at this distance under these conditions. Many years ago, the US Army did a series of tests with 30-06 match/sniper ammo using the old 173gn US military target FMJBT bullet. The results showed 1,225 fps terminal velocity was a key barrier, never mind 100 fps lower for the speed of sound. Under 1225, groups doubled and wind changes had an exaggerated effect compared to the same bullet above 1225 fps. The 175gn SMK may or may not be less affected - it is a very good bullet for trans and subsonic speed transitions, but without a doubt every bullet suffers to some degree ballistically as it enters and passes through the trans-sonic speed zone. Trans-sonics start at around 1.2 MACH, 1,350 fps, in 'standard' ballistic conditions which the M118LR bullet drops to at not much beyond 800 yards. Some years back US Army publicity went on about the M24 sniper rifle / M118LR capability at 1,000, but interestingly some USMC snipers rather more quietly commented that performance 'fell off a cliff' beyond 800M, ie a little under 900 yards. That ties in with the ballistics, but a LOT depends on ambient conditions.
Even in good conditions, you just didn't shoot 10-inch groups at this distance with this set-up. The F-Class 5-ring is a shade over 10-inch diameter and even today with far more advanced 308 ballistics using 200gn very high BC bullets from some
very capable precision rifles and equally good shooters there are very few F/TR match 'possibles' shot at 1,000. As has been said, you don't need much uncorrected wind change to take you out of the circle. Hitting a 10-inch gong first shot without sighters is
much harder and a real challenge for any rifle / cartridge combination, but much more so, the shooter.
The other factor to be aware of over many long-range challenge / milk jug etc videos, are ambient conditions. External ballistics several thousand feet above sea level and in 90-deg air temperatures are
very different from what most of us shoot in here - ie with thinner air, drag is reduced and bullets slow much less at any particular distance. Notice how many US videos on these shoots are on high altitude desert plateaus in what are pretty warm conditions. Let them come to Barry Buddon Ranges on the east coast of Scotland on a winter's day (or even a chilly summer day!) and see how many hit a 10-inch gong with any cartridge over any number of shots. (Decades ago, there were ELR competitions shot there with the 303 Number 4 rifle using flat army lorry load-beds as firing points driven up behind the 1,000 yard line - but the targets were about the size of a small house!)
PS I did eventually get that 308 rifle to shoot at longer distances after a fashion. It involved the ancient 190gn SMK (still a very competent L-R design even now and used by the 1,200 yard 'Match Rifle' 308 shooters for many years) with a pretty 'hairy' load of Viht N550.