I'm loading some 500 NE 3.25" rounds for a friend whose DR is in Zim. As I'm taking my 500 NE 3" there in August for a hunt with him, I'll bring along a box of loaded 3.25" cartridges along with my 3" ones.

I have been unable to find spec max COAL for the 3.25" version - is it 4.0" (based on the 3.750" for the 3")? I'll use 570 grain monolithics for both. Any help would be appreciated,as I won't have an opportunity to try the loaded rounds in the DR before they are delivered.

Assuming you are using the correct length of brass and CEB BBW #13 570s...just seat them so that the bullet sits in the case mouth in exactly the same position as as your 3" cases. If you are using Sam's recommendation of seating depth in your 3"...it will be fine in any rifle as that is deep seating depth...right over the top band that is.

BTW...coal out of a book is not a very useful number with all these flat-nose bullets as those numbers were most likely generated for conventionl round-nose ogives.

Agree, but not having access to the rifle I'm loading for a starting spec is useful. The assumptions in your prior post are correct and confirms the plan I had I mind.

I did see a photo of side-by-side loaded 3" and 3.25" cartridges and there seems to be ~1/4" difference in COAL. Thanks.