Wally,

Here is what I recommend. Load up a few cases with black or 777 and chronograph the loads. That will be your "target" velocity. I sugest that you use Varget for your NFB loads. I have found that about %60 load density is required to get on velocity. To determaine load density, fill up your case to the location of where the base of the bullet is after seating, then weigh it. This is %100 load density. I recommend you start at 50% with kapok or foam fillers. If it is "hot" drop 5 grains. If it is slow, keep adding 2 grains until she regulates. Don't exceed the target velocity by more than 100 fps.

This is my opinion. However, please seek another before proceeding.

Question: Are the barrels fluid steel or Damascus?