60-odd years ago, Ihelped a friend load 45-70-500 cartridges for original trap-door Springfields. As I remember, we used 13 grains of Unique as our load approximating the original black powder load. He never had a problem with excess pressures. The Lyman Handbook of Cast Bullets gives aload of 15 grains of Unique and a 500 grain gas check bullet(#437406) velocity of 1350 fps, and the Lyman Cast bullet Handbook gives a velocity of 1010 fps with an 482 grain bullet (#457406) with12 grains of Unique. The Lyman Black Powder Handbook & Loading Manual gives loads for the 45-70-500 Government (500 grains –bullet #457125) 60 grains (volume) Pyrodex RS as1055 fps and a pressure of 15,500 (CUP). The 45-70-500 was originally a black powder cartridge, but most people today load with some form of smokeless. I have always wondered why most people who use muzzleloaders have a prejudice against using smokeless in mass produced muzzle loaders, just because they are stamped “Black Powder Only”
If you look in the Lyman Black Powder Handbook and Loading Manual 2d Edition, You will find a lot of pressures in the 20,000 to 25,000 PSI range, and even 28,000PSI for a 3-pellet 50 grain Pyrodex load, which is maximum for CVS Magnum rifles. Lots of people on this forum have no problem with Pyrodex,777, or Blackhorn, but freak out at the suggestion of loading with Unique, 24000 or Blue Dot, even though the latter produce lower pressures at reasonable velocities and are infinitely cleaner burning and less corrosive. Shoot Pyrodex and not clean it with water and you will have pitting sooner rather than later.
In this video, the posters try to deliberately blow up a CVA traditional cap lock muzzle loader. As you will see if you watch it, it is not all that easy. First, they try overloading it with black powder, even filling the barrel with it and putting two balls in the end.
When this does not work, they put in an 80 grain volume equivalent of H110 (I've no idea what the actual weight is, but the maximum load of H110 for the 500 S&W Magnum cartridge behind a 500 grain projectile is 33 grains, and gives a pressure of 51,900 psi.) The result of this obvious overload is a slight bulge in the barrel.
If you look in the Lyman Black Powder Handbook and Loading Manual 2d Edition, You will find a lot of pressures in the 20,000 to 25,000 PSI range, and even 28,000PSI for a 3-pellet 50 grain Pyrodex load, which is maximum for CVS Magnum rifles. Lots of people on this forum have no problem with Pyrodex,777, or Blackhorn, but freak out at the suggestion of loading with Unique, 24000 or Blue Dot, even though the latter produce lower pressures at reasonable velocities and are infinitely cleaner burning and less corrosive. Shoot Pyrodex and not clean it with water and you will have pitting sooner rather than later.
In this video, the posters try to deliberately blow up a CVA traditional cap lock muzzle loader. As you will see if you watch it, it is not all that easy. First, they try overloading it with black powder, even filling the barrel with it and putting two balls in the end.
When this does not work, they put in an 80 grain volume equivalent of H110 (I've no idea what the actual weight is, but the maximum load of H110 for the 500 S&W Magnum cartridge behind a 500 grain projectile is 33 grains, and gives a pressure of 51,900 psi.) The result of this obvious overload is a slight bulge in the barrel.
