Forster Tap-O-Cap

>> Forster Tap-O-Cap :: By J. Marshall Stanton on 2002-02-16
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In this age of “New And Improved”, a move pervading blackpowder-shooting trends is for more fire, and hotter ignition systems. Although functionally superior, especially in high humidity, low temperature conditions, these new super-ignition systems aren’t always needed, or possible. Too there remains amongst blue-smoke shooters, a persistent independent streak that yearns for simplicity and self-reliance. Towards this latter end I write.
Although not new on the market, the Forster Tap-O-Cap enjoys limited retail distribution, and little or no current press. After all, old news doesn’t sell new magazines! The truth is, some older products are indeed news to a generation newly entering the shooting sports. I’ve been using the pictured Tap-O-Cap for at least ten years, with superb success, and exceptionally dependable ignition.

Now, what is a Tap-O-Cap? It is simply an ingeniously designed die and punch tool-set marketed along with what amounts to a modified paper punch for the express purpose of making your own No.11 percussion caps for black powder arms. The skirts for the percussion cap are formed by the die from aluminum beverage cans, and the priming medium from toy caps for a child’s cap-pistol. Simplistic? Perhaps, but it is very effective, easy to make and economical.


Using scissors or shears, cut an aluminum beverage can around both top and bottom, then cut the remaining cylinder top to bottom. This will produce a flat piece of aluminum from which to cut strips about ½” wide. These strips feed into a horizontal slot in the die body, from which the percussion cap skirt is formed. A punch assembly, hollow in the center, and having a serrated end, is inserted into the die, then struck with a wooden or plastic mallet. This hollow punch assembly cuts out a round piece of aluminum from the strip inserted into the die body, and in the same motion, forms the skirt over a tapered mandrel in the bottom of the die as the punch reaches the bottom of the stroke. The tapered mandrel of the die body correctly forms the percussion cap skirt, and shoves the finished skirt up, into the hollow portion of the punch assembly, whereby the finished skirt is ejected through the top of the punch as finished skirts are progressively shoved through the hollow core.


The priming agent for these homegrown percussion caps, are derived from kid’s toy caps. The tool included for this step appears as an ordinary paper punch, which it is, just with a very specific size punch. This punch is perfectly sized such that the resulting punch-outs fit snugly inside the aluminum percussion cap skirts, and coinciding roughly with the diameter of a typical priming charge in a roll of caps manufactured for repeating cap-guns.

Selection of toy caps is all-important when determining the reliability of the percussion cap. In today’s politically correct toy departments and toy stores, toy caps are frequently a scarce resource, much less finding any selection to choose from. The pictured American West brand of caps from Tootsietoy, are reliable performers, with concentrated priming charges in very consistent, well shaped spots on the roll-caps. The amount and intensity of these priming charges has proven to be exceedingly consistent from package to package.

There are other brands I have used in the past, most of which were made in Taiwan, and have proven superior to all others, however their availability at this time is unknown, and I’m still working on a large supply of them purchased seven or eight years ago from a variety store going out of business locally. If several brands are available, by all means try them all, and select the most consistent, and hottest caps from them.

Forster includes a small wooden dowel properly sized for inserting punched-out cap priming circles into the formed aluminum skirt of the percussion caps. For my purposes, I prefer just to grind the point from a sixteen-penny framing nail, and using the blunt ended nail to seat caps into the skirt. These priming charges must be firmly seated to the bottom of the skirts for reliable ignition. While one charge may be adequate, I’ve always enjoyed the utmost of reliability in these homemade percussion caps when two priming charges are inserted into each skirt instead of one. Interestingly, I’ve found no help in ignition by the addition of yet another charge, making three caps per skirt, as opposed to just the two mentioned above. On the down-side it seems that the third priming charge takes up too much internal space in the aluminum skirt, and impairs the seating of the percussion cap on standard No.11 nipples.

Now, about performance: I’ve used these percussion caps exclusively on my cap-and-ball revolvers for many, many years, and have found them totally reliable while contributing some of the very best accuracy ever achieved with these fine guns. As an added bonus, these homemade percussion caps, because they have slightly tapered skirts, fit the nipples, especially on these revolvers much more tightly than commercial percussion caps. This equates to nearly zero incidences of percussion caps coming off nipples due to recoil during firing! In long guns, I’ve found performance to be on a par with RWS and CCI percussion caps, when proper toy caps are obtained for this use. However, the shooting I do with muzzle-loaders and cap-and-ball revolvers is done 100% with black powder, usually FFFg. Using traditional black powder, these caps give complete reliability, however, if employed in lighting-off Pyrodex, Clean-Shot, or Black Canyon powders, the reliability issue of ignition is dubious at best, especially in humid or extremely cold conditions. But then again, if you’re using homemade percussion caps, you’re probably too much of a purist for substitute powders.

While not widely advertised, nor widely distributed, the Forster Tap-O-Cap is an outstanding tool of ageless durability, and adds an interesting wrinkle in the already time-consuming pursuit of muzzle loading!

To purchase the Forster Tap-O-Cap, we know of only one online retailer consistently stocking this item, Midsouth Shooter’s Supply, the link below will take you directly to this item on their shopping cart: