In my Lyell 500 BPE damascus tubed DR I use his load with 72 grns Varget smokeless. A foam backer rod and a 440ish gr. bullet sized to .512. This brings both tube together but high at 50 yds. I've tried a 380 bullet w/o luck. I also have tried paper patching but a naked lubed bullet works great so why bother.
and LOTS of dacron
The Alex Henry 577/500 works just as well with the same set up but different powder