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Here are a few photos and explanations of how I load my 45-70 black powder hunting cartridges. Brass:
Remington (Winchester brass has more capacity) You need a hot magnum primer to set the powder off. Winchester and Federal magnum primers are acknowledged to be hot enough for our purpose. Flash holes are drilled to get optimum ignition. Once drilled, mark those cases for use with black powder only since they may not be safe loaded with hot modern loads such as used in the Ruger single shots, etc. Cases should be full length resized, trimmed to uniform length and then expanded with an appropriate neck expander/case mouth belling die. I use Lee dies that are equipped with a special BP expanding die (measures .458 rather than the standard .454 and also expands the case a bit deeper than the standard die. (see photo below of both expander dies and powder compression die) Powder capacity is based upon loading 5.0 to 5.3 grains of powder (measured by volume) per 1/10 inch of case capacity. Case capacity is the depth of the case minus the seating depth of the bullet and any wad or grease cookie you may use. Wads and grease cookies are not mentioned here since this process is geared to simplified and time efficient loading of ammunition for hunting purposes. If you want to load lighter charges of BP, YOU MAY NEED TO USE FILLERS OR WADS!!!! Leaving an air space between BP and the base of the bullet has an effect similar to shooting a rifle with an obstruction in the barrel. You could end up with a bulged chamber. Here's an example of determining powder capacity; A given case has a full depth of 1.875 inch. The selected bullet will be seated to a depth of .5625. Subtracting seating depth from case depth leaves 1.3125 inch of powder capacity. at 5 grains per 10th inch of capacity, the load would be 65.6 grains of powder. At 5.3 grains of powder per inch, the load would be 69.56 grains of powder. These charges are based upon volumetric measure as measured with the type of measure used in the field by muzzle loaders. Using the actual weight of the powder will not work since the densities of various powder brands and grades varies greatly. Next, set your loading bench powder measure to throw that amount of powder. The actual weight of the charge is irrelevant! The ratio of the volume of powder to the case capacity as measured above is the important thing. In order to make room for the bullet, you must compress the powder. You can pour through a drop tube and then slightly compress the charge when seating the bullet or you can use a powder compression die. You can't compress the powder more than a little when seating since the soft bullet will expand in the bore ride nose area and may not chamber due to bulging. The use of a drop tube alone will never allow you to load full house charges of BP. Not that that is a bad thing, I guess. Most match shooters use the drop tube and shoot at lower velocities in order to get better accuracy. Whether or not that is so, I have no idea. Mainly I load for hunting and therefore want acceptable hunting accuracy with maximum killing power. The photo below shows the expansion dies and compression die.
The expander on the left is the standard expander and case mouth belling die that comes with the Lee dies (measures .454). The center is a special BP expander die that goes deeper into the case. This expansion plug measures .458 and allows seating the soft lead bullets without deforming them. The bronze colored plug is a powder compression die and, measures .453. this is the compression die used to compress your powder to the correct depth so as to seat the bullet firmly on top of the powder. Bullet selectionYour bullets need to be those designed for black powder! BP bullets are bore ride nose designs. That means that upon loading, the smaller diameter nose of the bullet extends into the rifled portion of the barrel. This design leaves more case capacity for the large bullets and is essential to getting good performance. Also, the lube grooves need to be large and lubed with BP lubricant as opposed to modern lubes. Bullets should be cast on the soft side ranging from 1/10 to 1/40 tin/lead ratio. Pure lead often works just fine.
Above are five 45-70 bullets starting at the left is a 385 grain bullet from a Dixie Gun Works mold that I got for about ten bucks. They shoot great!. Next is a 405 grain slug from Mid Kansas Bullets sized to .458 and lubed with SPG by Mid Ks. Next is a 500 grain bullet from a Lee mold designed for a gas check. This bullet is not suited for BP since the lube grooves are small and the gas check is unnecessary. It does, however have the necessary bore ride nose feature. Next is a 500 grain bullet from a Lee mold that is a replica of the 500 grain bullet loaded for the 1873 Trapdoor rifle. A very good bullet. Next and last is a 480 grain bullet from Mid Kansas that is soft cast, as is their 405, and sized to .458 and lubed with SPG. This is also a very good bullet. These aren't the only selections out there. I'm putting them here so that you can see the bore ride nose feature. These bullets are seated so that the case just covers the last lube groove. It may have to go deeper if it won't chamber. Often they must be seated all the way out to the end of the first driving band where the bore ride nose begins, depending upon the chamber. I don't crimp my loads but only squeeze the case mouth down far enough to take the bell out and allow it to chamber. The photo below is a loaded 480 grain Mid Ks bullet on top of 70 grains (by weight) of 1.5f Swiss powder. Swiss powder is denser and heavier than Goex. The 70 grains of Swiss comes to a compression ratio of about 5.1 grains per 1/10 of an inch of case capacity with this particular bullet. Seventy grains of Goex ff (by weight) would slightly exceed my max of 5.3 grains of powder (volume measure) per 1/10 inch of case capacity with this bullet.
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