Richard, no disrespect meant - but I am neither a Cabela's sales rep trying to sell something, nor a Ten-X ammunition company rep, empowered to speak for them.
IMHO, since the box isn't marked as being loaded with blackpowder, I would assume a smokeless powder was used - and as I posted above - ANY smokeless load, strong or weak, has diferent pressure characteristics than blacpowder.
You want to fire new ammo in an old gun.
It's your gun, and your health - but you might want to talk to the horse's mouth first, and speak with Ten-X.