That's a nice deal for those barrels, if I had the money I'd really like I try one. I know the 105 problem early on but still read some guys getting hot lots of 105 ammo. There saying there only getting about 3 reloads and about 7+ from ammo that's normal pressure. Maybe just guys in hot temps and the powder is heat sensitive.Btw, X-Caliber has one of their frequent 20% sales going on now, you could order exactly what you want for $275 + shipping if you can wait a little while to get it.
I went RLGS on my 18", and it was doing well with an SA bleed off about 8.5 turns out, which is about where I run my Grendel and .223s. +1 would probably be good, but wasn't an option, I'd go +2 for longer barrels (my +2 21" is very smooth shooting and hasn't bobbled).
I haven't noticed the Hornady black being particularly hot, the first batch or two were loaded a bit long and were in the lands on some rifles, but they fixed that a while ago.
be cool if hornady came out with a crossover load, 75-90 grain that would work for varmint and large game to. Even the lighter 6mms have pretty good bc so will reach out fine.