If all three bulged the case neck, you've likely got an expander in your die that leaves the neck sized to accept .308 bullets. This is enough neck tension on a cast bullet to size it down some. You need a larger expander ball. Most mosins will accept up to a .317 sized bullet without needing neck turning, the Finnishicon might have a tighter neck, I don't know. My Russianicon will. It has a .316 groove diameter, so I need a bullet that big. Night Owl Enterprises, aka NOE bullet molds makes some oversize versions of Lyman bullet molds for the Mosin. I use the 316365 spitzer design, but for a caster starting out, some of the roundnose designs would be less frustration. I see they have some 314299 and 316299 molds in stock now.

NOE Bullet Moulds