Howdy
Mike glosses over it a bit, but he makes quick mention of a Square Load. A Square Load in Black Powder shotshells is one where the
volume of powder and shot are the same. Notice I did not say weight, I said volume. What tends to happen if you put too much powder into a shotshell for any given volume of shot is the powder will overpower the shot, blowing a hole in the pattern.
Putting less powder than shot in by volume is not a problem. But putting more powder than shot by volume can tend to blow holes in your pattern.
I load Black Powder shotshells for Cowboy Action Shooting. The nail method is great, but I need a lot of shells, so I use my old MEC Jr. I am not going to get into the argument about whether or not BP can be ignited by a static spark, suffice it to say I am probably the last person on the planet who refused to put Black Powder into the plastic bottle on my MEC Jr. I dip my powder by hand using a Lee dipper.
I use wads that I buy from Circle Fly.
http://www.circlefly.com/html/welcome.html
You can buy Circle Fly wads from several outlets, but I included their web page because they have an excellent discussion about loading BP shotshells with their wads. Look for it.
My normal load is actually a bit less than a Square Load. I use the biggest dipper in the Lee dipper set, 4.3CC, of powder. This works out to only about 2 1/3 drams of powder. I forget exactly how many grains, probably somewhere around 60. I use the standard charge bar on my MEC Jr to drop 1 1/8 ounces of shot. I usually use #8.
On the MEC I decap and reprime as usual. Then I take the primed hull off the press and pour in 4.3CC of FFg, usually Schuetzen, but any Black Powder will do. Then back on the press I seat a 1/8" thick Circle Fly Over Powder wad. I take it off the press one more time and use a 5/8" piece of dowel rod to compress the powder under the wad just a bit, so I can hear it crunch. It actually compresses it very little. I don't hit the dowel rod, I just lean on it. Back on the press I seat a 3/4" Circle Fly cushion wad, then I dump in my 1 1/8 ounces of #8. Finally, I seat a thin Over Shot card over the shot, and crimp the shell as usual using the last two stations of the MEC.
In truth, I do not need the Over Shot card, but with the shot column I have built up my crimps tend to be a tiny bit concave, so I put the card in to level them out and prevent any shot from escaping.
I can load about 3 boxes an hour with this method.
One further note about dipping powder. I always pour a good quantity of powder into a coffee cup. Then I dip it just like I was scooping ice cream. I dip out a heaping dipper of powder. I do not tap it or shake it or anything to settle the powder. I simply use a piece of index card to scrape off the dipper level with the top.
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Most guys who make BP shotshells for Cowboy Action Shooting actually do not use separate wads like I do. Most use plastic wads, it is less work. The go to wad for years was the old Winchester Red wad. Unfortunately Winchester stopped making them a while ago. But Claybuster makes a good copy.
The Claybuster wad number is CB1138-12. Seventh down on the page. This wad is good because it does not eat up a lot of the space needed for the powder charge. BP loads take up a lot more space than Smokeless loads.
http://www.claybusterwads.com/index.php/winchester-style
Yes, the wad tends to leave melted plastic behind, but most guys clean it out with really hot water and elbow grease.