Working up a load for a friend of mine. He is getting 6-8" groups at 200 yards with factory loaded Remington Corelocks. No worries there, his technique is good and the rifle doesn't seem to be real finicky.
I have used a comparator to measure Head to Ogive lengths on all the facotry loads and have a real good idea where to seat bullets for him. We have a few factory loads left to shoot over my chronograph.
I was hoping to just start him with Varget, but published loads for Varget in 7mm rem Mag only go up to 130 grains, we are looking at 170 grain bullets.
The Hodgdon powders in the extreme line that are listed for 7mm Rem Mag at 170 grains are Retumbo, H1000 and H4831.
Anyone have better or worse results with any of those three in 7mm Rem Mag? Other brands products we shoudl consider? He is willing to hunt down to zero degrees F, so I'd rather set him up with a powder good from the get go.