The Home Machinist!

Hi,
Is anyone on this list familiar with the "Forster Tap-o-Cap" I would like to duplicate it or make something similar for my own use. It is used to make your own percussion caps using aluminum from cans and roll caps used in toy pistols. Thanks, Rick

It's probably been 50 years since I played with any capgun caps, but back then, the compound was highly corrosive, worse than regular black powder. I remember it would corrode the heck out of the breech area of a capgun.

Modern caps are non-corrosive, I think they use lead styphnate or lead azide. (The old-time ones used silver or mercury fulminate. Exceedingly touchy stuff, and I think corrosive as well.)

All that said, I suppose you could make them, with a home-made die of sorts, and the toy caps as you describe. I don't know how you'd get the little crimp-lines that are on a commercial cap, that help it stay on the nipple.

Hi Pete,
Thanks for the input. I did try making a simple die to form the cup, but it was a failure. The aluminum (beer can) tore and when I increased the clearances they came out lopsided and unuseable. I suspect you would need some sort of a star shaped die to form a proper crimp. I have since bought a box of No. 11 caps at the local gun shop. End of Experiment! Rick

Pete,
was the compound more corrosive or was part of the problem the nasty die cast metal the cap guns were made of?
Think of the cap guns we could make now
Regards,
Nick

Probably both, Nick. I remember how the diecast metal would corrode almost to nothing, but I also remember banging caps on the pavement with a hammer, and the hammer rusting overnight.

I read somewhere that they used a variation on "Armstrong's Mixture", which is a combination of potassium chlorate, red phosphorus, ground glass, and sulfur, but that stuff is so sensitive it will go off if you LOOK crosseyed at it.

That said, it's fairly certain that the compound contained some chlorate, or more likely perchlorate, which is somewhat more stable. Both of them break down to oxygen and potassium chloride, which is corrosive like common salt, only more so. But it probably also included charcoal, since I recall it was dark grey, not black like "regular" gunpowder; its smoke also smelled different from gunpowder's, more "metallic".

I probably shortened my life measurably by smelling the stuff.

I've got one haven't used it in years. I hear caps are had to find, I use to use it all the time, my rifle looks ok, and the nipple still looks great.


Gerald C

PeteH wrote:It's probably been 50 years since I played with any capgun caps,
I think they use lead styphnate or lead azide. (The old-time ones used silver or mercury fulminate. Exceedingly touchy stuff, and I think corrosive as well.)

I can surely relate to the 50+ years thing! FWIW, the "fulminate" compounds all tend to be corosive; mercury fulminate was responsible for many a rusted bore. Most of them, other than mercury, are a bit too sensitive to use safely. Some were used years back, to load toy "torpedoes" which exploded when thrown against a hard surface. These contained coarse sand admixed with the active powder, to bring about it's percussion detonation.

CB&Q

The mercury caused the brass to fail; the potassium chlorate is what caused the rusted bores if not cleaned out with a water bearing solvent.

I ordered two Tap-O-Caps kits from Midsouth Shooters Supply in 2004 and I have used them eversince. Online inquiries always point you to Midsouth as a possible source, but I have heard that Forster no longer makes them. But maybe Forster would give you written permission to make your own. I use four paper caps caps in each of my percussion caps for Sure Fire Never Fail ignition. If you have never seen a Tap-O-Cap, then it has a maybe 0.04" slit in its side for inserting 3/4" wide strips of aluminum beverage can material which is cut by a very hard knife edged piston as that piston is pushed downward with only hand pressure. A center post of about 1/8" diameter is below where the 7/16 diameter aluminum disc is cut by the piston, and a hole which is slightly larger than that about 1/8" post runs through the center of the punch and as soon as you push the piston down with a sharp rap of you palm...A perfect #11 percussion cap pops out of the hole in the top of the piston. Hopefully this description is enough for you to be able to figure out how to make your own custom Percussio Cap Maker.

havent heard them mentioned in a long time

web search will turn up a few images and instructions

http://www.forsterproducts.com/client_i ... 00-001.pdf

I asked a good buddy of mine who is a bonafide Machinist to make a larger one so that I could punch out musket cap cups, but after he had researched it he said that it was covered up in patents. It was he who suggested asking Forster for written permission to make one. I can just about bet you that Forster would like to have someone to make up a couple hundred of them because they get a lot of telephone calls about whenever they are going to start making them again. One of my kits is in a jar of break fluid/kerosene mixture for safe keeping. A spare is always great to have.

It is not a violation to copy and make a patented or copyrighted item for your own use. You cannot make them in order to sell and/or make a profit.

You cannot photocopy a book legally in order to read it without paying for a copy, but you can hand copy the book and keep it legally. You can't sell it and giving it away is probably a violation.

Making a cap maker FOR YOUR OWN USE isn't illegal, even if you use an existing one as a pattern.