1. Can I safely use commercial .45-70 ammo with smokeless powder? I have read that modern replicas can handle smokeless better than the original. If not,
2. Where can I obtain commercial .45-70 with blackpowder? Seems they only make this caliber with smokeless. Thanks!
You can shoot smokeless in any of the replica Sharps chambered in 45-70.
Cabela's sells blackpowder cartridges made by Goex if you were wanting to try that route. Course it's alot cheaper to load your own...but that's another story.
Yes you can shoot conventional commercial ammo from your Sharps reproduction. The ammo I WOULDN'T shoot in it is Buffalo Bore or other higher pressure ammo made specifically for modern firearms only such as modern falling blocks like Ruger #1s or Marlin lever actions. The "standard" pressure loads such as offered by Remington or Winchester are OK to shoot in your Sharps.
Buffalo Bore has changed their listing the last few years Stalking Bear. Now days it includes any falling block made since 1900.
That one of mine has stood up to a few thousand rounds of smokeless and black. My favorite smokeless load is sending the 535 gr. Postell bullet along at 1600 fps. while Buffalo Bore shows their 500 gr. at 1625 fps. while mine with the 500 gr. Barnes are right at 1550 fps.
BTW...is that a Sharps you're holding in your avatar? Appears to be from what I can tell.