I was chambering .44 Russian in a 44-40 chamber, not .44 magnum or .44 Spl.
According to the case spec dimensions in my Speer reloading books, here's how the .44 Russian and the 44-40 stack up:
.44 Russian
- case length - .9700"
- rim thickness - .0600
- diameter ahead of rim - .4570"
44-40
- length up to beginning of shoulder taper - .9275"
- rim thickness - .0650"
- diameter ahead of rim - .4711"
It does look like there would be some case bulging. Only way to find out is to fire a few rds.
My caliper needs a new battery, but in eyeballing my Winchester, Remington and a new batch of Star Line brass, there are several case dimension differences evident. For example, I don't get the case bulges with my Winchester brass that I do with the Star Line, suggesting that the latter is thicker walled.
When I first got my Uberti .44 Russian, I had some .44 Spl. turned down by a friend. There was a difference in wall thickness at the case mouth, but things worked out rather well.
I've also had .455 cases made from .45 Long Colt, trimming to length and thinning the rims. Again, they were not 100% factory spec, but they loaded just fine.
As to why would I want to do this? It has always interested me how ammunition for a particular calibre can be made from other sources and using various dies.
Call it the winter cabin fever crazies.