Bartholomew,
I don't have anything for the 75/77 gr rounds from The Wound Ballistics Review. But from Tatjana and Brou's most recent test, they share much of the same type of data. Below is some of that data:
It appears the Nosler 77 gr NATO pressure load from Black Hills penetrates to an average depth of 12.5". I think the SAAMI version penetrates an average of 13-14". The average largest recovered fragment was 34.2 grains (55.6% fragmentation) for the NATO load. They recorded a neck length around 1.6", which as I recall was nearly identical to the SAAMI pressure load tested earlier. The wound cavity was listed at 3.875" at a depth of 4-5".
Now, here's the comparsion between the 77 gr NATO and SAAMI versions. It appears either will work very well at CQB distance and I suspect even the SAAMI version will still be fragmenting out past 100 yards, even from an M4 length barrel. Again, here's the comparison and I am borrowing this straight from Tatjana's post:
Comparison to SAAMI pressure 77 grain nosler (no cannelure):
Recovered Weight:
SAAMI 77gr: 74.2gr.
NATO 77 gr: 73.7 gr.
Fragmentation:
SAAMI 77 gr: 58.3%
NATO 77 gr: 55.6%
Largest Recovered Fragment:
SAAMI 77gr: 32.1gr.
NATO 77 gr: 34.2 gr.
Neck:
SAAMI 77gr: 1.57"
NATO 77gr: 1.60"
View Quote
If you want more in-depth information, just check out the post. It's still on the front page of this forum. It appears based on what has been presented here and elsewhere that both the 75 and 77 gr (whether NATO or SAAMI pressure) are a bit better than the 68 gr BH. It's not a huge difference, but big enough many would rather use it if they had a choice. The NATO load will obviously be better at longer ranges, but anything inside 100 yards should be handled well by either. But if I had a 1:9 twist barrel and didn't feel like spending money on a new one, I wouldn't be overly worried about using the 68 gr. I have a 1:9 twist Bushy and I just use the 68 gr as opposed to rebarreling. While the 75/77 gr loads are better, I feel the 68 is good enough. Therefore I don't worry about it.
I hope this was of some help.
-Charging Handle