I have not had very good luck with anything over 55gr in my Ruger 77V. It was made in ‘75 and is very accurate with 52gr Sierra MKs so that’s what I shoot mostly. We have a 2” gong at 200yds at my range and hitting it with this rifle is so easy my Grandkids do can do it.
Longer heavier bullets just won’t shoot well in this rifle. It’s a good honest old varmint rifle with a Canjar trigger and 12x Leopold scope, at my age I doubt I will ever rebarrel it, but if I did I would go with a faster twist barrel for sure.