I do not have a 'Mills Belt' for .45-70.

I have a 'Hurlburt Belt' for .30-40 and a messed-up .30-40 Mills Belt.

The head diameter of the .45-70 cartridge measures around .498". The rim diameter is around .603".

The head diameter of the .30-40 cartridge measures around .453". The rim diameter is around .536" to .541", depending on brand.

IMHO - What is significant, is the circumference of the two cartridges, because, that is how they are held in a woven cartridge belt.

(.30-40) - .453" head dia. X 3.14 = 1.42"

(.45-70) - .498" head dia. X 3.14 = 1.56"

The difference in the circumference of the two cartridges is .140 inches. (This is the approximate thickness of Nickel stacked on a Quarter). 

FWIW - I imagine the length of each woven loop, on a .45-70 cartridge belt and .30-40 cartridge belt, would reflect this .140 inch difference.

My .30-40 'Hurlburt' cartridge-belt tightly holds Krag cartridges, but, it cannot be reasonably stretched to hold a .45-70 cartridge.

I imagine Krag cartridges might be retained in .45-70 woven-belt loops merely by their rims and gravity. The cartridges would be very loose and easily fall out the top.

With Krag related items it helps to be patient and know what you want. In time, things have a way of 'finding you'.

Attached:

1. - .30-40 Hurlburt belt - note .45-70 cartridge will not fit. (Belt was originally Khaki and was dyed blue at some point and has faded).

2. - The two cartridges compared - (The vernier shows .140", or, the difference in circumference of .45-70 and .30-40 cartridges, in the head area).

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