I was trying to decide between a Larue Stealth with a 1/8, or a Noveske SS with a 1/7 twist.
I intend on primarily shooting Black Hills 77gr (40%) and 62gr M855 (40%), with some 55gr M193 (20%).
Would the 1/8 be a better overall twist, or would a 1/7 be just as effective?
from my research i went with the 1/7
Both would work well, but I am personally a huge fan of the Noveske SS barrels. It would be my choice.
Both would be stainless steel. I was just trying to decide between the 1/7 and 1/8.
I read somewhere that 1/8 was a better overall twist because it works with lighter bullets as well as the 77gr.
I was already assuming you were talking SS barrels since you mentioned the Stealth. In your case you are mostly shooting (80%) ammo that will do very well in either 1:7 or 1:8. You may have a slight advantage with the 55gr in the 1:8 however I really am sold on the Noveske SS barrels. In reality it would be hard to go wrong with either and both are top notch IMO.
My daughter uses a RRA NM4 Match Rifle with a 1/8 twist, about 90% of the time she uses Black Hills 77gr Match ammo. The other 10% she uses 55gr but she won’t use it for shooting past 300 yards. She hasn’t had any issues with ammo aside from ballistic differences at the 300 yard line which were minor.
She used my 6920 and Black Hills 77gr Match ammo for her first match last year. No issues from the 600 yards line.
I have heard that the ‘best’ twist is 1.75 for the 62gr round but I have nothing to back that up with 
If you are going to go above 77gr you would be better off with the 1/8 but if you planning on keeping targets within 600 yrds, either barrel would work fine.