As Eaglet said the edge is based on a 300Rum necked up that has a little more case
capacity than the 338 RUM .
I built my 338 RUM on a weatherby MK 5 action that was 1/10 of an inch longer than
most other actions allowing me to seat the bullet long eleminating the differance in
capacity between the 338 RUM and the 300/338 RUM.( Edge )
You can also use the 375 RUM cases for the edge by necking them down .
As far as performance there's little or no difference between the two and factory
ammo is available for the 338 RUM.
J E CUSTOM