Well, I have to chime in here. Sorry to say that there is information that is not 100% correct...most of what anitqueguy is posting seems to be intended to ensure that someone does not try to use ammunition that is not suited for the trapdoor action. This is a cautionary statement by that poster and contains, in some part, reality. However there are exceptions. before I go any further I have to say that I have been using the Springfield Trapdoor in Black powder competition and long range matches since the late 1970's. As a result there are a lot of awards on the wall attributed to the both the guns and the loads I have been feeding them...the Trapdoor can shoot and does shoot incredibly well with the proper loads.
As for factory loads in the trapdoor...most light bullet factory loads are thoroughly unsafe for the trapdoor as they are high velocity and high pressure cartridges. Before choosing a factory load, check the manufacturers data sheets...a lot of them give pressures and velocities. Look for 405 grain ammunition with a sub 1500 FPS velocity and pressure under 18,000 c.u.p. Most, if not all, 405 grains bullets are copper jacketed, though some may contain other alloys lending them to higher velocity loadings. Extensive use of jacketed bullets in the old trapdoor may cause a few problems. Though what I have seen regarding bore damage over the years is most likely related to the use of smokeless powder, not jacketed bullets.
There is minor problem with jacketed bullets in the trapdoor...they are too small in diameter. Even though dimensionally the trapdoor 45-70 is bored to 0.458", the nominal size of jacketed 45-70 bullets can be 0.457" and rarely any larger. After a century of use the bore of trapdoor will be worn to the point of measuring .0460 to 0.462. There will be considerable gas loss in the barrel when smokeless powder is used under a jacketed bullet in the trapdoor...this is experience, not theory talking. With cast lead bullets I was using a larger size (0.461") with a felt wad in loads with both black powder and smokeless powder. The trapdoors I used this in shot circles around the high priced shoulder dis-locators and their kind...thus a wall full of shooting awards.
So...what is the answer to the OP's question about factory loads safe int eh trapdoor??? Do your research first then choose the right factory load combination that will be safe in your gun then moderate your shooting to limit wear on the barrel. If the trapdoor is a pristine 95% plus original finish gun then I will beat you with a stick for shooting it, you do not want to what I would do if you broke it!!!!


However if it is a 40 to 60% gun, then have fun, and don't forget to post pics