Sectional density for 115 grain pills:
.257 = .248
.277/6.8 = .214
Not sure if SD is a big deal anyway, at least at most combat ranges, given that it seems that fragmentation is a current design goal of anti personnel rounds. SD is important when you are hunting elk or Cape Buffalo, but not so sure in this particular role, unless designers are looking at reducing fragmentation to improve penetration through various barriers.
Also, the BC listed from the Remington page compares with Hornady's 68 grain BTHP Match bullet (.330), so I suspect that the 5.56 77 grain OTM, launched at basically the same velocity, would still fly a bit flatter. But the 115 pill does give you more energy out there.
I would like to know what the terminal performance of that bullet would be at 400/500/600 meters given that velocity has fallen off quite a bit. You are probably below the threshold for fragmentation out there and at that point your SD comes into play.