Bull Shop, Dan C. has done this and posted on Aimmo a few months ago. As I recall he reported only on straight wall cases . I have visited with Dan and trust him as a reliable source of information. If I were to build up a new load using fillers I would feel fine starting with foam peanuts. Gianni.

Fillers are a bad idea that refuses to die. Lots of guys have ringed barrels and bulged chambers. In spite of this we hear about it all the time. They can ruin your rifle. Older soft steel barrels are more prone to ringing than modern ones.

You can point the rifle up before you shoot to settle the powder to the base. Even better would be to use a powder suitable for the application. I have not researched it but, I would bet the cast bullet bench rest guys don't use fillers. They get fantastic accuracy.