As long as the shaft does not contact the die, the North Forks I've resized slip thru a drawing die as easy or easier than a lead core soft.

I know there might be disagreement here, but I am still about 99.9% sure the trouble that may be caused by copper-alloy monos involves dimensional incompatability of some part of the bullet with the gun, not the mere fact that the bullet is a copper-alloy solid. Personally, I think the shaft diameter is the problem, not even really the driving bands {within reason}. Check out the truncated cone of that NF pic'd above and you can see the almost immediate relief in front of the driving bands, and essentially no portion of the bullet afore the DB's is "bore riding". Meaning, nothing to jam into the rifling of a gun whose interior dimensions are "out of spec" to the bullet, so-to-speak. In effect, this type of bullet, due to the hardness {advantage} of copper alloy, can be designed almost the opposite of modern cast bullets with their long bore riding portions. The thing looks almost like a Pope bullet from the old days.

A long bore riding portion shouldn't be a problem in a gun that fit it/that it fit, but some guns might have rifling/bore/groove dimensions that would not be compatible with a production mono sporting a long bore-riding portion {or a shaft diameter that got into the lands}. In such a case, "one size does not fit all".

I have a big hunch this whole "OSR" topic {probably under a different name} has been fully documented and experimented by Ordnance engineers, particularly during autofrettage experiments and process development {in pursuit of thinner/lighter artillery barrels} and/or AP round development, probably the former, but I can't locate such documents. Maybe others can? It is a hunch, anyhow...

As the saying goes, there is nothing new under the sun, especially true in my opinion about anything involving The Gun. Unfortunately we do not have anybody with past or present artillery ordnance education here?

This whole topic has panned out in the opposite of the way I figured it would. Most of these things seem to be eventually handled cleanly when somebody with technical expertise wades in and clears the air, oftimes it seems from a military engineering background. Maybe that person has merely not yet surfaced.