Speer Shot Capsules are available in 38, 44 and 45. A big advantage of the capsules is the ability to load more shot without having to use special brass. The capsules also come with a cupped plastic gas seal wad which works better than a card wad. However they are not without problems.
The big disadvantage of the capsules is they must be made of very fragile plastic so they break apart on firing. To prevent pulling out from recoil, you must crimp the capsule securely. When you do this, about a third the time the capsule shatters and you start over. If you do not crimp securely, the capsule will pull out from the light recoil of firing another shot cartridge and bind up the revolver. This limits you to one shot load in the first up position.
Even with a "good" crimp the capsule will sometimes pull after a shot load is fired. A cylinder full of shot shells is asking for a jam. Don't even think about firing a standard cartridge first, the increased recoil will pull the capsule almost every time.
To make capsules work, use clean brass. Fired cases are OK but there must be no residue in the case.
Charge with powder.
Seat the capsules by hand just inside the case.
Apply a small amount of rubber cement around the capsule ahead of the case mouth.
Immediately seat to the recommended OAL and lightly crimp just enough to remove the case mouth bell.
Wipe off any excess rubber cement.
Allow to dry overnight.
Clean out the seating die with lacquer thinner.
Capsules loaded this way will not pull when a regular round is fired and will not tie up your gun. You can load a full cylinder for “Revolver Skeet” or to fend off a company of Copperheads.
The least expensive way to get shot for a small number of loads is to disassemble shotgun shells. Number 9 shot is the smallest size commonly available and works well in 38 and 44 capsules. Number 8 or 7 ½ give fewer shot, but greater penetration. Number 12 shot is desirable in 38 capsules, and gives dense patterns in larger capsules, but is usually available only in 25 pound bags.
Light loads are often recommended with shot loads to improve the pattern. Light loads with Speer Capsules will sometimes fail to rupture the capsule, giving a single projectile. Use Speers load recommendations which come in each box.
Always test your shot cartridges to confirm performance.