Samson, I agree with Marsh in one sense but respectfully disagree in another. The answer is it depends on the manufacturer and ammo. I've owned and shot several TDs over the years. There are some jacketed "factory" loads that are definitely way too hot to use in a springfield and there are some that are safe. A few years ago all the factory loads were safe since companies like Remington, Federal, Winchester, etc only manufactured smokeless .45-70 ammo that was safe in a TD due to liability concerns. Since then due to the huge popularity of rifles like the Marlin Guide guns and some modern single shot rifles several smaller companies are offering "factory" ammo loaded well in excess of the max pressure capabilities of a TD. There is no question that black powder loads are certainly safe (as you likely can't get enough black powder in a case to overpressure a TD), but if you check with Remington, Federal, and Winchester I believe you will find that all their "factory" loads are safe. Of course they will tell you your rifles has to be in good condition, and if it an original TD should be checked out by a qualified gunsmith. Finally you need to consider that the metal in original TD is softer than modern rifles and extensive use of jacketed bullets will accelerate bore wear.