[Rigmarol]

If your friend is an experienced caster then this probably doesn't apply as he should already know it;

He should slug is barrel to determine it's diameter then add .002 to get the diameter his bullets should be sized to.

Then he needs to be sure his lube is not failing him. Lot's of home recipies for lube, tallow based seems very popular.

Keyholing has happened to me in my .45-70 sharps shooting the .405gn bullet. And I was barely able to hit the target backer board at 100yards. I feel your friend's frustration.

I moved to a heavier bullet, a lube wad under the bullet over both Black Powder and 777 and dramatically improved my own results.

So, it may be sizing and lube, or it may need a heavier bullet.

Good luck.