Friday, June 09, 2023

Homemade Percussion Caps

Last week while I was on a staycation I prepared a batch of homemade No.11 percussion caps, using the tool from and their Prime-All priming compound. I tried them out a couple days later.

I left out the tan/off-white component, which is either dextrin or gelatin intended to be a binder. By most accounts it works poorly as suck. Instead, I took a 1 oz. plastic bottle with a needle oiler tip, put a few millimeters of Duco cement in the bottom, then filled the rest with acetone to make a saturated solution.

Using a CCI Large pistol primer tray as a loading block I filled about 20 caps at a time with the mixed Prime-All compound and then put a drop or two of the Duco/acetone solution in it. Using a small piece of bamboo cut from a chop stick I gently tamped down the wet mixture.

After the caps were visibly dry I put another drop or two of the solution in the caps and let them dry in the open air overnight. I wanted to ensure that enough Duco cement was deposited in them to keep the priming compound in place. Duco is a nitrocellulose based glue so it's flammable even when dry.

For safety's sake make sure that you crush any lumps in the components before mixing them. Crushing lumps after the components are mixed can cause detonation.

Note that I did not have luck punching caps out of beverage cans, even doubled. I keep punching right through the material. Rather, I used 0.005" thick copper foil which is a more durable material.

I tried them in my Pietta 1860 Sheriff which has Slixshot nipples installed.

  • 6 caps to clear the nipples: All popped. I noticed they make less noise than CCI, Remington, or RWS caps.
  • 6 shots loaded from paper cartridges with 25 grains of Scheutzen 3Fg BP: The first 3 went off OK but the next 3 popped but failed to set off the BP. I recapped those cylinder and none set off the powder. I recapped once more using RWS 1075+ caps and all 3 chambers went off. They may work better with paper cartridges if I increase the amount of priming compound.
  • 6 shots with 25 grains of Scheutzen loaded from a flask: All 6 went off properly.
  • 6 shots with 25 grains of Triple 7 3Fg BP substitute, which has a higher ignition temp: All 6 went off properly.

The caps on shots with 25 grains of BP held together but flowed a little back into the safety notch in the hammer nose.

The caps on the Triple 7 loads all perforated but the skirts held together.

None of the caps fragmented and I had no jams. Some came off easily while others had to be pried off either with my fingers or pocketknife. All 27 caps I dropped the hammer on ignited properly.

Since the Prime-All fouling is corrosive I cleaned the gun with water and MPro 7 after getting home, and oiled everything with FP-10. I left it disassembled overnight to confirm I'm not going to get any rust and everything looks fine.

Overall, I consider the home made caps using the Prime-All compound a success for use in percussion revolvers and I'm sure they'd work fine in an underhammer. I need to test them in a sidelock rifle or pistol.

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