Hi all, do you think that the sholder on a 470NE would headspace reliably if it didn't have a rim? Or would it need to be steeper?

How much can you compress a load without worring about the bullet backing out? Playing with Quickload looks like W760 would work rather well for this.

Lar-I use cannelure bullets so I am able to compress
10% and crimp.If bullet don't have crimping groove, I put
one on with case spinner lathe.Ed.

Okay, Looks like the .475 might be too large on the RUM case. So what about getting a 300RUM reamer with floating pilot, put a 458 pilot on it to cut the chamber, then ream for the neck and throat and make it a 458RUM. I wonder if there would be any real gain over the 458 Lott?

Lar-Should be a little steeper, the shoulder about
.020 bigger, and about 4 times steeper shoulder.Ed.

Lar45 -

If one takes a 300 RUM and necks it up to 458, leaving a .050" wide shoulder to headspace on, yes, a significant improvement over the Lott, ie, 102gr full case vs 120gr (for the 458-300)... but still 14gr short of the 460 Wby. I've uploaded to our website a drawing comparing the two www.gmdr.com/levern/458-300rum.jpg

do shoot straight,
greg
www.gmdr.com