All about revolver nipples

[Texian]

ALL ABOUT REVOLVER NIPPLES

Matching the right nipple to a percussion revolver and figuring out which cap fits that nipple is usually a hit-or-miss, pot-luck game of chance. It is irritating to order a set of replacement nipples, only to discover them to be incorrect for your gun.

Hoping to make this a less chancy endeavor, I’ve measured the nipples from a number of guns and from a selection of replacement nipples. To share this info and learn from others knowledgeable in this area is the reason I have started this topic. I hope many of you can add to this information and correct me where I have erred.

As no doubt you have noticed, other than the right thread pattern, black powder revolver nipple dimensions themselves vary widely from one gun maker to another or even from one gun to another by the same maker. The same is true among BP nipple makers. Nipple maker X might say that their nipple is a replacement for the nipples used by gun builder C, but when measured, they are totally different (on your gun). Then the nipples provided by nipple maker X can prove to be totally different from those made by nipple makers Y and Z, which are, additionally, neither the same as the other. To confound the problem, the nipples used by a gun builder can differ from year to year, model to model, or even across the nipples found in one particular cylinder.

This makes it a bit of guesswork to locate a new set of nipples that will work properly with your gun. It is especially true when vendors selling the nipples fail to provide enough information about their product to enable you to purchase the correct nipple for your particular need. The geometry of correct nipple fit is somewhat complex. Just saying that nipple X will fit gun Y is just not enough information.

The first thing you will notice is that if a nipple height dimension is mentioned by a vendor, it is often the length of the cone. This may or may not be useful info. If it means only the length of the conical section, that would be worthless data. The only meaningful measurement pertaining to the nipple height is the dimension from the seat of the flange to the top of the conical section. To avoid confusion I choose to call this dimension (flange seat to top of cone) the nipple HEIGHT instead of cone length.

From one maker to the next, the flange section can differ greatly in height, as can the length of the conical section. It is only the sum of these two dimensions in which we are interested. I have photographed a sample nipple and marked it with a diagram of the various dimensions (See the Nipple Dimensions diagram that follows the definitions below). The terms I use for the dimensions may differ from those you use, but I will be consistent in using them in this discussion.

NIPPLE DIMENSIONS

Length      Total nipple length, from top of cone to bottom of threads
Height         From top of conical section to bottom of flange seat
Thread      Length of threaded part
Flange      From bottom of flange seat up to start of conical section
Cone         From top of nipple to bottom of conical section
Thread Diameter   Outside diameter of threads
Flange Diameter   Outside diameter of flange part or base
Flats Width      Width of the flats ground into the flange to accept a wrench
Cone Top      Diameter at the top of the conical section (before any bevel)
Cone Bottom   Diameter at the bottom of the conical section (before flare)   



I would suggest that everyone who plans to make any changes to the nipples for a cap and ball revolver should purchase a caliper that reads in thousandths of an inch. These cost from $15 to $50 and can often be found, used, for much less. They come in digital, dial, and vernier versions. A micrometer can work, but is much less convenient and cannot make other measurements, such as inside diameters, depth of cylinders, etc. If you are measurementally challenged, you should choose a digital caliper, because they read out directly in inches or millimeters. My preference is a dial caliper simply because I hate being battery dependent. Due to the theory of its operation, a vernier caliper is harder to read for most folks. Plus, good eyesight is a help when using a vernier readout.

Enough for now. I'll post more later.

Cheers,

Texian

[Texian]

It took me awhile to figure out a way to get from a spreadsheet file to a JPEG.

These are the measurements for the nipples from various revolvers that I measured.



Later I'll post the dimensions of various replacement nipples.

Texian

[Pustic]

Thanks for posting this. I saved it to a word file then saved it as a pdf. 

[Texian]

These are the dimensions of some standard replacement nipples.

Often the heights of these nipples are not very close to the heights of the original nipples in the specified guns.

[Pustic]

Thanks for posting this too. I put it all on a pdf file. 

[Mad Dog Stafford]

Great information there.

[Texian]

Continuing from the previous posts, the HEIGHT of a nipple is the dimension from where the flange seats against the cylinder to the tippy-top of the conical section of the nipple. Or, if you prefer, the total length of the nipple minus the length of the threaded section, will give you the nipple HEIGHT. Having nipples of the correct height is important for consistent cap ignition.

Before getting into the details of this discussion, it will help to agree on what is the proper nipple height for a particular revolver.

Most gunsmiths advise that, with a nipple of the proper height in place, the hammer face will not touch the nipple, even when pressure is applied to the hammer when the hammer is down—this is called under-travel. If it does touch, this is undesirable and is called over-travel, which will cause wear, damage or even breakage to the nipple and hammer. Note that it is not necessary for the hammer to ever actually impact the nipple in order to ignite the cap. Changing the nipples for shorter ones is one way to alleviate this problem. For later, keep in mind that hammer under-travel/over-travel can be adjusted in other ways, if all other options fail.

The reason the caps will still fire without the hammer actually striking the nipple is because the thickness of the percussive material in the cap and the foil of the cap is somewhere in the neighborhood of .040” to .050”, depending upon which brand cap you measure. Here are some cap thicknesses I have randomly sampled. To do this I first measured the total LENGTH of a short piece of metal rod that all of the caps would fit on loosely (fully seat). Then, with the cap in place, I measured again. (For the photos I used a star bit for the probe.)





The difference between the readings provided the dimensions listed here for the thickness of 4 different brands of percussion caps:

Top of cap rests above top of nipple by;
Remington, about .042”
CCI Magnum, about .050”
Winchester Magnum BP, about .050”
RWS, about .047”

Theoretically, you could have hammer under-travel of .020” to .040” and the cap would still fire. In practice, it probably is best to keep it between .010” and .030”.

Hammer Clearance Test
At this point it will be helpful to have a “feeler gauge.” This is a tool which allows you to measure very narrow gaps. In C&B guns this tool is used to measure the flash gap, which is the distance between the barrel and the cylinder face when the cylinder is pressed as far rearward as it will go.



How do you test for this? With the hammer down—under firm thumb pressure—you should still have most, if not all, of the flash gap you had when the hammer was at half-cock. If you have .005” flash gap at half-cock, you should still have .005” flash gap with the hammer pressed hard down. But if you have a large flash gap—say .018”—then it might be acceptable to have only .010” with the hammer down hard.

Test if Nipple Stands too High
A quick test to see if a nipple sits too high is to press the hammer down hard with your thumb and see if it drags on the nipple by wobbling the cylinder against the stop (bolt). If it drags on the hammer, the nipple sits too high. Here are the results of a test with 6 Remington New Model Army (1858) revolvers:

   Gun (Yr)            FlashGap@Half-cock   Gap W/Hammer Down        Result
R29 Pietta (2001) -           .006” - - - - - - - - - - - .000” - - - - - - - - - - - - - Drags
R37 Pietta (2007) -          .005” - - - - - - - - - - - .000” - - - - - - - - - - - - - Drags
R41 Pietta (2011) -          .008” - - - - - - - - - - - .000” - - - - - - - - - - - - - Drags
Santa Barbara (72)          .009” - - - - - - - - - - - .009” - - - - - - - - - - - Does not drag
Navy Arms (1967) -         .006” - - - - - - - - - - - .006” - - - - - - - - - - - Does not drag
Uberti (2012) - - - - -         .003” - - - - - - - - - - - .003” - - - - - - - - - - - Does not drag
(The Navy Arms is an early Uberti)

If the gun passes the test with the flash gap being the same at half-cock as with the hammer down hard, that is great, but there might be the opposite problem . . . the nipple could even be too short. You can’t know unless you perform the following test.

Test if the Nipple Sits too Low
To test if a nipple’s height is too low, back the nipple out of the cylinder by a quarter turn and retest. Continue this until the nipple drags on the hammer. A quarter turn is about .007” to .009” +/-, depending on the thread pitch. To figure this exactly for a given nipple pitch, here are some examples:

For a 12-28 tpi thread pitch:

        1.000” / (28 X 4) = Height added by ¼ turn = .009”

For a 6 X .75mm thread:

         Tpi = 25.4mm / .75 = 33.87tpi

1.000” / (4 X 33.87) = Height added by ¼ turn = .007”

For a 5.5 X .9mm thread:

   Tpi = 25.4mm / .9 = 28.22tpi

1.000” / (4 X 28.22) = Height added by ¼ turn = .009”

Note that all nipples on a cylinder should be tested this way as you will often find one or more nipples may sit higher or lower than the others (there could be several causes for this problem, which will be discussed later). Once you have made these tests and have established whether your nipples are the correct length, or too long, or too short and by how much, you should next establish the actual dimensions of the nipples in your gun by measurement.

More later,

Texian

[Pustic]

More?  How much more?    I'll save this to word, and pdf it after you get it all on here.         

[Texian]

From here we can progress to actually locating a replacement nipple. To demonstrate here the measuring technique, I measured a nipple from Track of the Wolf, which is sold as a replacement nipple for Remington replica revolvers with a thread pattern of 6 x .75mm, item number PIR-I. The same procedure applies when you measure the nipples from your gun. When measured with a dial caliper, the dimensions of this replacement nipple were found to be:

LENGTH = .526”



Using the caliper depth probe (sticks out at the bottom of the caliper), the length of the thread section is found to be:

THREAD = .227”



By subtracting the length of the threaded part from the total length of the nipple, the HEIGHT of the nipple is found to be:   .526” - .227” = .299”

It is possible to measure the HEIGHT another way, but it is harder because there is not any way to get the caliper blades to fit on the nipple correctly. However, there is a place on the back of most calipers where the slider (the part with the dial mounted) stands above the jaw on the rail bar. This offset provides a place to catch the flange on the rail jaw side and still catch the top of the cone on the other jaw.

Unfortunately, there is a built in gap between those parts (note how the jaws notch outward slightly at that point), so the measurement requires a correction factor. To calculate that factor, place the nipple in the gap and re-measure the full length.



In my case, the new measurement was .476”. But the correct length—determined by previous measurement—was .526” (see above). This tells me I must add .050” to whatever length I measure using this method. Then I measured the HEIGHT using this offset on the back of the caliper:



When I did this I found the height from the seat of the flange to the top of the cone to be .251”. After I added the .050” correction factor, the HEIGHT was calculated to be .301”. That is only a difference of .002” between direct measurement and computing the HEIGHT by subtracting the thread length . . . not bad.

So, we can say the actual HEIGHT of the nipple (distance from flange seat to cone top) would probably be between those 2 numbers:

HEIGHT  =  .300”

As we know and was explained earlier, this is the dimension that you need to know for proper fit. But will this nipple fit your gun?

To find out, I compared this dimension to some original nipples removed from the same revolvers previously tested for hammer over-travel:

Gun  / Yr  _____  LENGTH __THREAD ____HEIGHT ___ PITCH
R29 Pietta / 01 ___   .545”  _____  .229”  _____  .316” __ 6 X .75mm
R37 Pietta / 07 ___   .538”  _____  .224”  _____  .314” __ 6 X .75mm
R41 Pietta / 12 ___   .541”  _____  .227”  _____  .314” __ 6 X .75mm
SB / 1972 _______   .515”  _____  .200”  _____  .315” __ 6 X .75mm
Navy Arms/1967__  .441”  _____  .161”  _____  .283” __ 6 X .75mm
Uberti / 2012 _____ .501”  _____  .213”  _____  .287” __ 5.5 X .9mm
(SB = Santa Barbara, the Navy Arms is an Uberti)

From test firing I know that all 6 guns, with the original nipples, would reliably ignite properly fitted caps, all other things being equal.

However, from the previous post, the Hammer Clearance Test indicated that the nipples were too long (sat too high) on 3 of the guns (the Piettas), and this is borne out by the presence of nipple marks on the hammer faces of those 3 revolvers.

In gun R29, I replaced the factory nipple (.316” height) with the shorter (.300”) replacement nipple, Track of the Wolf item number PIR-I. The gun still failed to pass the Hammer Clearance Test . . . even that shorter nipple was too long. A live test confirmed that caps on that shorter nipple still ignited reliably. Better, but not perfect.

Further, placing this shorter nipple in the Santa Barbara—where the .315” high nipple was a perfect height—caused ignition to become erratic. The same nipple, placed in the Navy Arms Uberti, resulted in the nipple standing proud, causing the hammer to rub and impact the nipple. The 2012 Uberti has a different thread pitch, so the test could not be made with it, but a taller nipple would cause the same hammer over-travel problem.

In summary, once you have the data from your gun and its nipples, the replacement nipple chart can be used to help locate a correct nipple or avoid purchase of a totally incorrect nipple.

If anyone has measurements for any nipple part number not listed in the replacement nipple chart, I would be glad to add that data to the chart.

Next, an easy way to correctly determine the exact cap to use with any nipple.

Texian

[Pustic]

There's only two caps to choose from, 10's or 11's. If 10's are too small, 11's will fit, if 10's fit, then that's it, otherwise, it's the 11's.  If 11's are too big and you don't have 10's, pinch it. 

[Texian]

Hi Pustic.

Yep, that should work . . . in a pinch.  And many times that is exactly what we all do . . . or use a big stick.

However, being as I'm somewhat picky, and as there are about 8 or 9 different sizes of caps to choose from, bear with me and I'll refine that approach just a bit.

Thanks,

Texian

[NCBallBuster]

Great info, along with reading this you might just know everything there is to know about percussion caps.

[Texian]

Thanks, NCB, but I'm just a duffer compared to those like Captain Kirk and others here who really know their gun smithing stuff.

I'm just trying to put all in one place some general information that I have learned over the years.

Thanks,

Texian

[Texian]

At this point it seems appropriate to digress and cover percussion cap selection. So, let’s postpone discussing other more aggressive and difficult methods of correcting nipple height or shape and assume that a correctly fitting nipple has been installed in your revolver. Later I’ll explore some ways to modify your existing nipples to accept larger or smaller caps or make the nipples sit higher or lower.

Choosing the right percussion cap for your particular revolver/nipple setup can be as simple as doing it by trial and error. Some choose to just press a cap on and, if it stands proud or rubs on the blast shield or takes two strikes to ignite, just mash it on harder with a stick. Also, personal brand and size preferences are methods often used to make this selection.

If a cap is too loose, some shooters might just give it a good pinch . . . and it may stay on, or it may not. Some people contend that pinched caps can allow access for hot gases leading to “chain fires,” but I can’t address that question. I do know that I prefer to use caps that fit well to avoid any chance, however slight, of nipple side chain fires.

At any rate, there is a simple way to choose a cap that will make life easier. To begin testing, it is helpful to have an assortment of the available cap sizes. The cap sizes more or less available (excluding rare or antique sizes, such as 9 or 12), are listed here in order from smallest to largest (more or less):

RWS 1055
CCI 10
RWS 1075
Remington 10
CCI 11
Remington 11
Winchester 11

The order shown above can vary, dependent on cone shape. For example, a cone with a narrow top and a wide base (more volcano shaped than cylindrical) may accept a CCI 10 while a supposedly larger Remington 10 will not fit without forcing because the long skirt of the Remington 10 hits the sides of the cone before it seats fully. If you then force it, you'll split the skirt. Some older, more cylindrical cones, such as found on early Centaures and others may require RWS 1055 or #9 caps, if you can find them.

Also, keep in mind that the Remington 10 and the Remington 11 are the same diameter. It is the long skirt of the Remington 10 that allows it to grip a smaller diameter cone because it simply reaches down farther to where the cone is wider.

To perform this test, remove a nipple from your gun. It is easiest to find the correct size cap for a nipple if it is out of the gun where you can measure it.

Recalling the chart of cap thicknesses listed earlier, you can use it, or you can use the measurement method described previously to check the thickness of your own caps:

Top of cap rests above top of nipple by an average of;
    Remington, about .042”
    CCI Magnum, about .050”
    Winchester Magnum BP, about .050”
    RWS, about .047”

Testing to Find Correct Cap Size

With the nipple out of the gun, measure the total nipple length using your caliper.

Place a cap on the nipple and press it into place with just normal thumb pressure (for, say, a 14 year old girl). Do not bear down . . . you want to be able to remove it without resorting to violence. Next, measure the combined length of the nipple and the cap. If this combined length exceeds the sum of the nipple length and the cap thickness for that cap (from the chart above) by more than several thousandths of an inch, then that cap did not fully seat and may be too small for that nipple. Try the next larger cap. If it seats fully and feels secure, that may be the cap you should use. Personal preferences come into play here regarding what you think the word secure means for you. For me it means the cap will stay on reliably, but I can get it back off by worrying it with my fingernail.

As an example, the replacement nipple I measured earlier had a total length of .526”. A Remington 11 cap added .042” for a new length of .568”. When I measured the combined length it was .571” . . . about .003” taller than expected but confirming that it was adequately seated. When I checked with a Remington 10, it was a really tight fit and sat a bit taller, indicating it was probably too small of a cap for that nipple, but still possible to use.

Keep in mind that caps in the same box may vary in thickness by as much as .005”, so make allowances. To be more precise in your tests, you could measure the thickness of the exact cap you will use instead of using the average thicknesses from the chart above.

Using this method you can quickly eliminate cap brands or sizes that seem to fit but are actually too small. In this way you can avoid the practice of forcing undersized caps onto nipples with a tool. Undersize caps installed by excessive force often split, lose their elasticity and grip, and are then actually a looser fit and more likely to fall off than the correct cap installed with normal pressure. Also, undersize caps often do not seat fully and may require several hammer strikes to ignite. The only justification for using a tool to force a cap down on a nipple is for those occasions where the only caps you have are too small and expediency takes precedence over perfection.

That’s all I think I know about caps.

Next, some discussion of ways to modify your existing revolver nipples and hammer clearances to the tolerances you want or prefer.

Cheers,

Texian

[Fingers McGee]

Ya know, there is a really good primer on caps & nipples by Mako over on CAS City that was started a couple years ago.  It has numerous drawngs and dimensions and has been archived under their Dark Arts forum.    Here's the link http://www.cascity.com/forumhall/index.php/topic,35696.0.html