I lost my CIP pdf files so I can't answer the question. Would it be possible to rebore a stock Ruger RSM 375H&H into a 404 Jeffery or is the 404 too small a cartridge?

Thanks Brad

The concern arises, of course, because the short-necked .375H&H comes to full shoulder diameter of .448" while it is located at a point that lies in the long-necked .404 Jeffery's neck. Neck-1 diameter at junction with .404 Jeffery shoulder is .455" diameter, but the .375 H&H case body is about .453" diameter at that distance from base (since it expands baseward with that huge H&H taper), at the same point where the .404 Jeffery Neck-1 is located.

It appears to me that it will just barely work.
At the critical point of cleaning up the .375H&H chamber, the 404 Jeffery neck-1 diameter is about .002" bigger than the point of concern on the .375 H&H case body.
Below that, the .404 Jeffery swallows the rest of the .375 H&H chamber.


No barrel set back will be required, just careful chambering after the rebore to .423.
That would be spiffy.
Thanks for the idea.