Casting your own bullets does help.
I'm not sure of the metal ratios of the store baught bullets are.
I don't think they expand enough.
My Grandfather and I use a 1:20 mix when we cast.
One part Tin to 20 Parts Lead.
I have also known people to use 1:30, 1:40,
IMO, these bullets are too soft.
Our mold we had to get custom made.
I'm not sure with your rifle Blittz, if you would have to get custom made,
If so, here is the web site we ordered ours from.
/
http://www.brooksmoulds.com/
Works great.