Cap Gun Primer: Correct Cone Length

[Mako]

This is in answer to a question I got from an individual the other day about modifying a Treso tube to optimize it for a #10 Remington or #10 CCI cap.  The Treso tubes were designed for #11 caps  but as many shooters have found they can use #10 caps if they use a seating stick and additional force to fully seat the cap.  In most cases a Remington #10 cap will work because the cap will relieve itself at one or more of the petal junctions or "crotches."  Even with the beginnings of a split the Remington cap will usually  have the integrity to provide the grasping force necessary to keep it on the tube.

The reason this is possible with a Treso tube is primarily because the taper on the Treso tube is very slight and over the years the cap manufacturers have actually converged the cap sizes to the point there is not a large separation in the apparent sizes of the #10 and #11 Caps.  Even with this convergence, standard factory tubes will rarely accept both #10 and #11 caps, this includes the Remington caps which use the skirt length to engage the taper at different points.

I have mentioned before that even though I normally use unmodified Treso tubes with Remington #11 caps I have two sets of Treso tubes I can move between my different cap guns that I have specifically modified to be optimized for #10 caps instead of the #11s they were designed for.  The fit I wanted was the light press fit you would get with a Remington #11 on an unmodified Treso cone.  In the past I was unable to get Remington #11 caps and I temporarily switched to Remington #10 caps using these modified Treso tubes.

First I'll recap the dimensions of the currently available caps.  Since I last posted measurements I now have measurements from an additional sample of 100 Remington #10 and 100 #11 caps.  These are from three different new lots of #10 caps (and one old one) and 4 lots of #11s (and one old one). 20 caps were measured from each tin.



And now the diameters the Treso tubes need to me changed to to optimally fit #10 caps:




Note the two sets of dimensions and compare them to the Internal  Height on the chart of the Remington and CCi #10 caps.  Note the diameters are about .003" and .004" larger in diameter than the cap I.D.s which give you a light interference fit.

This is how the caps look on the modified tubes:




These tubes were modified using a CNC lathe which allowed precise profiling to the taper but the fit could be created with even a file and a tube chucked up in a drill motor.  The secret is to work slowly and measure the diameter at the correct gauge distance from the face of the tube.  If manually modifying tubes it would be best to choose one cap that is readily available and then work the tube until the diameter matches at the gauge height for that cap.

Regards,
Mako

[ROAnutz]

That is exactly what I did. I chucked my Treso's in a drill press and worked slowly with a fine file till the #10 CCI's fit. Forget using any kind of sand paper. I tried that first and it barely polished it. No measurable change had been made. File it or forget it. 

Blomqusit and Treso seem to work with no issues using RWS 1075+ or Remington #11's. They will not fit CCI #10's. I've hardly ever been able to find Remington #11's . I just bought a 1000 RWS's so I'm good there.
I have a bunch of different nipples I use, depending what caps I'm using.

One thing I have noticed is that that the RWS 1075 +'s are significantly hotter than either Remington or CCI/Winchester. A definitively noticeable increase in KABOOM vs the others. I noticed this while shooting caps only....so there was no powder charge to mask it.

I want to use my CED chrono and test my 5-1/2" ROA with 45 grains of Triple 7 (I had Clements deepen the chambers) , a 210 grain BigLube Bullet that I hollow pointed in a jig I bought (works great!) and an RWS 1075+.

I use a BigLube Tower of Power to load everything as equally possible.

1) Stock Ruger
2) Treso's
3) Uncle Mike's
4) Blomquist.

My 5-1/2" ROA is anything but stock and I'm proud of it, yet just mortified what I've spent on it. I've run out of things to do to it....although a 5-1/2" octagon and cool front sight from Clement is somehow starting to make sense. I don't know....maybe it's caused by the Japanese radiation leaks.

[Mako]

ROAnutz,
I read your post about the caps the other day and it got me thinking about RWS 1075s again.

The caps you have are the "plus" variety which are called "magnum" primers by other manufacturers, that's why they are louder. If you get the CCI magnum caps they are louder as well.

Do me a favor, if you have any means of measuring them,  I'm going to ask you for the same dimensions I asked Hellgate to give me for his RWS #55 caps.  If you don't have a caliper then don't worry about it, sooner or later I'll bum some from someone locally, or buy some.  



I'm really interested in the internal dimension.  I want to see how much priming compound they have in them compared to the plain 1075s.  One more thing tell me what color the sealer on the priming compound is, the plain 1075s are green.



I have RWS 1075 caps but I haven't seen them for sale in a while.  As I told Hellgate this came up a few weeks ago talking among other cap gun shooters and none of us have seen anything other than the "Plus" variety for a while.  I'm sure they will work fine and if cartridge  primers are any indication I can't tell any difference in performance with a black powder pistol cartridge.  Magnum primers are manufactured to help muzzleloading rifle shooters get good ignition. Personally I've never had a problem, this is also why they make those "Hot Shot" tubes which are the antithesis of the Treso Tubes we use to attenuate the back blast.  The Hot Shots actually have a larger flash hole in them.  I've never had a problem setting BP off, it's much easier than smokeless powder.

If they work, then use them is my motto...  

Best of luck,
Mako

[ROAnutz]

ROAnutz,
I read your post about the caps the other day and it got me thinking about RWS 1075s again.

The caps you have are the "plus" variety which are called "magnum" primers by other manufacturers, that's why they are louder. If you get the CCI magnum caps they are louder as well.



. Personally I've never had a problem, this is also why they make those "Hot Shot" tubes which are the antithesis of the Treso Tubes we use to attenuate the back blast.  The Hot Shots actually have a larger flash hole in them.  I've never had a problem setting BP off, it's much easier than smokeless powder.

Are you trying to say that you should not use magnum primers with small hole nipples, like the Treso's?

[Mako]

Are you trying to say that you should not use magnum primers with small hole nipples, like the Treso's?

Not at all.  I'm saying two things:

• We don't really need magnum primers for our pistols.  Black Powder is easy to set off.
• We don't need large flash holes like you find on tubes marketed by TC commonly known as "Hot Shot" tubes.  For the same reason as above.  In addition it is detrimental to revolver shooting because the large hole allows more back blast to come back through and the blast plays havoc with the caps.  We don't need more debris.

Magnum primers (not caps) are sold for three reasons.

• Large cartridges of smokeless powder use slow burning large grain powders which are harder to ignite.  The higher brisance of the magnum primers help assure consistent ignition.
• In Cold weather which is a common season for hunting in North America the higher brisance helps with the lower pressures and burn rates caused by lower temperatures.   
• The primer cups are thicker and actually a harder copper (they roll it to work harden it).  This prevents flow back around the firing pin into the firing pin hole we normally call "cratering".

On some magnum pistol primers the brisance is actually the same as standard primers, the difference is the primer cup thickness and hardness to prevent flowing of the primer back around the firing pin.  This is borne out by primer brisance tests where you can see the increased fountain on some and the same as regular primers on other brands.   Some people had resorted to rifle primers for the stronger cups, but the primers are dimensionally different in height and the primer pockets are different depths between rifle and pistol primers.

Magnum Caps are manufactured for the first two reasons the magnum rifle primers are marketed. They are aimed at the muzzleloading hunting market.  They will work fine on revolvers, the majority of the splitting and fragmenting is not from the priming compound, but from the back blast coming from the primary charge in the chamber venting back through the hole.

Large flash hole tubes are aimed at the single shot muzzleloading hunters market.  Personally I believe it is more hype than reality.  They accentuate the amount of primer charge getting to the powder charge.  There is considerable back blast coming back through the flash hole, but with a single shot weapon a fragmented or dislodged cap is not really a problem.  The rifles also have heavier mainsprings and will not be pushed back by the blast.  A lot of modern reproduction revolvers have wimpy mainsprings and we don't need more blast pushing on them.

Treso tubes are the perfect tube for the revolver, I have found nothing better.  They will work fine with magnum caps.  I also have Treso tubes on my Enfield and a .36 caliber long rifle and I find they work very well.

Sound good?

~Mako

[wildman1]

Mako, I would disagree with you on one thing here. I have a Traditions 50 cal Pa rifle and their nipple (cone) hole is so small that it allows almost no blowback, I agree with you on smaller hole less blowback, what I take issue with is your use of the term "hype" in relation to whether or not ya need a large flash hole. I used ta shoot matches with that rifle and would get fouling so bad the rifle would not fire. The fouling was in the breech plug between the nipple and the powder chamber. I removed the nipple, drilled it out and solved the problem. Yes, I did get blowback, depending on the charge it would sometimes blow the hammer to halfcock.  But it also kept the breech plug hole clear. WM

[zymurgeist]

Sounds like a problem with the spark path within the breech plug itself being too small. I may just be a nervous nelly but I worry about pieces of hot copper flying everywhere because the hole in the nipple is too big.

[wildman1]

Ever shoot a flintlock? WM

[Mako]

Mako, I would disagree with you on one thing here. I have a Traditions 50 cal Pa rifle and their nipple (cone) hole is so small that it allows almost no blowback, I agree with you on smaller hole less blowback, what I take issue with is your use of the term "hype" in relation to whether or not ya need a large flash hole. I used ta shoot matches with that rifle and would get fouling so bad the rifle would not fire. The fouling was in the breech plug between the nipple and the powder chamber. I removed the nipple, drilled it out and solved the problem. Yes, I did get blowback, depending on the charge it would sometimes blow the hammer to halfcock.  But it also kept the breech plug hole clear. WM

Wildman,
I had a reason for saying hype, read on...

You actually explain the problem and have the corrective actions all in your post.  Look at what you wrote...

I have a Traditions 50 cal Pa rifle and their nipple (cone) hole is so small...

I removed the nipple, drilled it out and solved the problem.

If you had started with a normal tube (with a normal flash hole) then you would not have ever made that statement.  By your own discovery you state the Traditions flash hole was too small for the tube interior geometry.  I know it's not your intention but don't confuse standard tubes with the "oversize" cross drilled Hot Shot aftermarket tubes.  You are mixing cherries and watermelons there.  You found the problem and you corrected it, but you have noted the correction now causes the hammer to be blown back to half cock.

As  I said you can get away with oversize flash holes on single shots, but they are anathema for revolvers.  You can also use Treso tubes very effectively on muzzlestuffers.   The Treso design is conducive to directing the combustiing priming compound into the breech.  You may have see this illustration before but is is a direct reverse engineered model of the 12-28 threaded Treso tubes for the Uberti pistols and the very recent production Uberti tubes.



I even went to the trouble to show the two step drilling for the major diameter on the Uberti tubes.  Uberti tubes didn't always look like this, they used to have a larger flash hole.  They made changes to their design when people began installing aftermarket tubes on their products.  I'm assuming they  didn't  go as small on the flash hole as Treso because Uberti makes their tubes from carbon steel and they would have problems with a lot of shooters who would let them get a bit of corrosion in the small opening.  Probably a good assumption though since that is sort of my area of specialty.

Back to your original problem and how does that undersized flash hole differ from a Treso tube?  The Treso tubes have a large primary chamber and gives the primer compound gas stream an area to initially expand into,  once gas has a vector it will continue in that direction, it really doesn't like to change direction.  You might try a Treso tube on that Traditions rifle of yours.  I have been happy with mine and I don't have a fouling or ignition problem.  I've suggested them to others as replacements if they have buggered up threads, they make oversize threaded tubes in .005" increments in five or six steps up in the 1:28 pitch.  You have to tap those breech plugs but you can save an old rifle.  I have had reports they worked better than ever after replacement and they had no issues with cold weather usage.  I'd venture to say your original tube had a small primary as well as exit hole.  

The Treso tubes are unique in the depth of the primary chambers, I have several other brands of aftermarket tubes and none of them have the short necked down section that Treso does. Some are necked down, but not as much or having such a short section of being necked down.  Treso remains unique not only because they are constructed of Aluminum Bronze alloy, but because of the the interior dimensions.  A lot of steel tubes would have erosion problems with the Treso Geometry.  I use two other Ampco alloys which are very similar the Treso alloy because they resist high temperature erosion of nozzles in an extreme environment better than any material we have tried to date.

As far as the hype goes check this out:



This is a TCA Hot Shot, the cross drilled holes seem like a good idea until you think about the gas flow under normal firing.  Is it really a good idea, or just a "different" idea?  People could reply and make the same claim about the Treso tubes.  But, there is a difference...The Treso tubes don't allow more back blast and they don't blow the hammer back to half cock.  Hot Shot shooters accept that as the consequence of having a "hotter" (translate that as higher, faster, sexier, cooler) tube.  

This thread was started as a primer for about revolver cones and cutting through the misconceptions, and remains that today. Let's not get too far off of the subject or we just make what was a nice tidy thread into an unwieldy series of posts going in and out of being on topic.

Regards,
Mako

[wildman1]

As soon as I drilled out the nipple I made a flash deflector that is held on by the nipple. most of the blowback is contained by the cup shape of the hammer, as a matter of fact if you don't pay attention you will actually get a buildup of expended caps in the hammer recess. I can honestly say I've never had a problem with that rifle and flying pieces of cap.  WM

[Mako]

Most people don't realize it, but There is a significant amount of gas that comes back through the flash hole on a standard percussion cap revolver.  The entire pistol is enveloped by a burning "cloud" of gas coming from the cylinder gap and the flash hole.

This sequence is from a high speed study done with an original Colt 1860.  Full attribution is given to Arthur Tobias  in his excellent study. Notice the initial flash from the cap as part of the charge escape around the periphery of the cap in the second and third photos in the sequence.  In the fourth photo it is evident the gas is being blown to the rear through the flash hole.  In fact there is burning gunpowder that has now passed around the sides of the hammer and is moving back towards the shooter before the bullet has left the barrel.



This is another shot of the Colt enveloped with a burning cloud of gas and smoke.  Once again the burning powder is seen shooting back over the hand of the shooter.



Treso tubes help attenuate this back blast.

~Mako

[Lefty Dude]

As always, Mako your post are great and very educational .

Thank you so much.

[Steel Horse Bailey]

Wonderful, Mako.  My hat is off to you and your great explanations and illustrations.

I need some clarification, if possible.  I couldn't find an real definition of "Brisiance."  From what little I found, it seems that my own definition I've been working under is wrong.  My definition is similar and perhaps serves to be "close enough for government work" but I like to be correct.

Also, weren't the Magnum caps created primarily aimed at the Pyrodex shooters?  In my own experience, real BP ignites easily and with about any cap/primer.  Pyrodex, which IS a real BP, but not like the newer subs (which I believe are citrus oriented) is somewhat harder to ignite.  As to the Magnum primers, what has been mentioned is right on, especially about cold temperature ignition.

Thanks again!

[wildman1]

Just shot my Uberti Cattleman Carbine for the first time yesterday and I will tell you those pictures are right on the button. I had much more debris flying back and around than I ever had with my long rifles, percussion or flintlocks. Nice pics Mako enjoyed as usual, especially now that I can see em. WM

[zymurgeist]

"This is a TCA Hot Shot, the cross drilled holes seem like a good idea until you think about the gas flow under normal firing."

What is the purpose of the cross drilled holes? It baffles me. 

[Steel Horse Bailey]

"This is a TCA Hot Shot, the cross drilled holes seem like a good idea until you think about the gas flow under normal firing."

What is the purpose of the cross drilled holes? It baffles me. 

I've often wondered about that myself.  I don't get a mental visualization that justifies cross-drilled holes, unless it is supposed to allow more oxygen into the mix.

[Mako]

Hey Steel Horse,
If you'll bear with my lengthy explanations I can make it plain for all.  Brisance actually has two meanings that we would be interested in.  The first is the common meaning used with explosives, propellants or other pyrotechnics.  Brisance is basically a "rate" metric.  It is the rate at which a combustion reaction reaches maximum pressure.  If an explosive charge has a sufficiently "high" brisance rate (lower time) then it can create a shock wave which is what you want from a "high explosive" a "low" explosive like BP doesn't have the shattering effect of a faster explosive because it has a shallow pressure curve and takes longer to make maximum pressure.

As an aside BP also has a lower final pressure and expansion velocity than other industrial or common explosives.  This makes it a better propellant than an explosive, just like nitrocellulose powder is a better propellant than an explosive.

The shattering effect is what the first commercial and military applications were looking for, brisance comes from the French word "briser" which means to break or shatter.

We also use the term when it comes to detonation trains, primers, initiators and in our case percussion caps.  In this sense it applies to two elements of the combustion process, the amount of burning gas generated and the distance it will travel.  So, it is volume and the distance which are usually, but not always interrelated.  You can add more of the base priming compound to increase the brisance of a cap or primer, or you can add an extender or booster.  The extender or booster may increase the velocity or the time it will burn (in some cases both). If you have an extender in a cartridge primer it may just allow the burning gas to project out further while it is still at the maximum temperature it will attain.

With an initiator train for a warhead we really don't care if we create excess pressure or debris because we're getting ready to make a big bang anyway.  In the case of precision shooting we usually want to minimize the effects of the primer and control our pressures and gas volumes with the propellant instead of the primer.  If you consult a common loading manual you will see differences in pressures with identical loads except for the primers and a warning you will see increased pressures if using certain magnum primers.

I am attaching a portion of a great article German Salazar wrote for the June 2008 issue of Precision Shooting.  These shooters are looking to control the most arcane aspect of each and every cartridge so the search for the primers that have the least amount of pressure deviation at the lowest brisance rate that will effectively ignite their powder.  I'm including it because the pictures illustrate the differences better than I can explain them.  Note these are Bench Rest primers, and look at the ignition and carry differences between these precision primers by manufacturer alone.



Now to address your astute comment about the common usage of "magnum" caps.  You are very correct!  

The problem powders are not so much Pyrodex but the other modern substitutes.  They are more difficult to ignite.  Now that being said the Pyrodex pellets are candidates for magnum caps.  I have sample cans of the substitutes but I really don't use them.  I get excited when I read about them and upon trying them it's sort of like "kissing your sister."  So I tend to relay information about ammunition and loads using Gunpowder and not substitutes.  

Real Gunpowder is very forgiving and really doesn't need the "new fangled" inventions, magnum caps or primers to set it off.  In fact attenuating the effects back through the flash hole is more of an issue with those of us that want to be competitive in timed shooting events.  I will literally use whatever components I have on hand when loading BP cartridges, it's really not picky.  But, I am very picky about my cones and how the caps I have on hand fit on those cones.  As I have written, I have had good success with Treso tubes on even muzzleloaders which probably lets the same amount of gas through the flash hole from the cap side (because of the internal geometry) as a standard primer, but then limits the gas flow coming back through the hole from the chamber.

Look at the sequence in my post above, look specifically at frame 2.  There is excess gas which can't make it through the flash hole on even that 138+ year old Colt's original tube. If it is given a larger primary chamber in the tube to start down then it can still have a sufficient volume to make it into the chamber and set off the powder with gobs of excess gas to spare.  There is obviously a lot of extra gas volume from the cap that continues into frame 3.  So a smaller hole with a lead in on the cap side will assure enough getting through for ignition while at the same time limiting the orifice size to let gas flow back through the hole.

This is how we are similar to the Bench Rest shooters, we want just enough gas into the chamber to assure consistent ignition.  But then the BR shooter are then concerned about it affecting their pressures, we are just concerned about that pressure having a large hole to get back out of.  If I get the time I may conduct some photo tests with caps and different tubes.  It would be interesting to see the difference in brisance coming out the chamber end of a cylinder with different flash hole sizes and primary tube chamber geometry.  Ideally I would take an old or damaged cylinder and face it off leaving only 1/8" or so of chamber to see the gas shape right at the flash hole exit instead of out at the end of the chamber.  If you look at the photos above you can see some of the primers have a nice gas head right at the exit, yet they don't project very far (they have "lower brisance").

Regards,
Mako

P.S.
On the cross drilling comment: priming compound already has it's own oxidizer and it couldn't entrain any air into the mix quickly enough to have any effect.  Primers, propellants and explosives all carry their own oxidizers and contrary to what you see in movies, TV and read in books they will go off in total vacuum sealed or unsealed, also underwater (or in any other environment) if the items which can be affected by moisture don't get wet.

[Claypipe]

The Treso tubes were designed for #11 caps  but as many shooters have found they can use #10 caps if they use a seating stick and additional force to fully seat the cap.

The thought of using extra force to seat caps makes me a mite nervous. Far better to handfit your nipples to the more commonly available caps.

These tubes were modified using a CNC lathe which allowed precise profiling to the taper but the fit could be created with even a file and a tube chucked up in a drill motor.  The secret is to work slowly and measure the diameter at the correct gauge distance from the face of the tube.  If manually modifying tubes it would be best to choose one cap that is readily available and then work the tube until the diameter matches at the gauge height for that cap.

While I agree on the use of a drill to handfit nipples, I would suggest that one would have an easier time using a fine grit knife sharpening stone lubricated with dishsoap or water base machinist oil, rather than be bothered with constantly having to stop and clean the file, which will fast become clogged with filings, especially when handfitting bronze nipples. Plus, use of the stone will give a better finish.

For gauging the right fit, I deaden a cap with penetrating oil, waiting a day to pick out the insides with a wooden toothpick. Using a second toothpick, I mark off the depth of the cap. Using the marked toothpick and the deaden cap, I can now guage my work. Remembering that I want a somewhat tight fit, so the caps don't jump off during recoil.

Great pictures mako, what program are you using for them?

Claypipe, the GunGnome

[Steel Horse Bailey]

Said by an old comic on a long gone TV show:  Ver-ry  Int-er-es-tink!

Thanks for the interesting display and clarification.  My definition of brisiance was the "soft vs. hard" one, but way less technical ... and not entirely correct, it seems.  That was not a term used in my Master Gunner training, which is where I did learn enough to see where your explanation clears up my misconceptions.

My experience with Mag percussion caps was from shooting a LOT of Pyrodex "back in the day" before I had a dependable supply of real Gunpowder.  I have some Trip 7 powder but have not yet used it, and have exactly ZERO experience with ANY of the other subs.  However, as you pointed out, some of the "new fangled" stuff needs more "oompfh" to ignite.  I got around that once with an experience in max loads in my (then) new 2nd Gen. Colt 1st Mod. Dragoon.  I put in around 20 grs. of KIK in the chamber, then topped it off with a 30 gr. Pyro Pellet, a lubed wad and a round ball.  Since the KIK was the initial powder ignited by the cap, no special percussion cap was used ... or needed ... and the pellet had NO problem igniting right along with the loose 3f KIK powder.  It was FUN, 'tho a bit wasteful.  It was VERY "energetic" - even more so than ANY other C&B I've ever fired or been around.  Not for the faint-of-heart!!  I was pleasantly surprised at #1 -- the accuracy, #2 - the recoil (MUCH more than any other BP load I've fired, 'tho still "nada" compared to some smokeyless loads), and since I fired over snow, #3 how little powder was unburned and was sent out the barrel to be thoroughly wasted.  The snow was surprisingly clean after these loads.  (If some of the other readers don't know what I'm referring to, if you fire over snow [like the oldtimers did when testing some of their loads] you'll probably be surprised at how much black residue will be on the snow in front of your firing position, which shows how much unburned powder is wasted upon firing.  I've HEARD tell that up to 50% of a load can be blown out the barrel either unburned or ignited & burning AFTER it has left the gun, therefore adding NOTHING to the fired round.  Simply wasted.  This applies primarily to handguns.)

Again, thanks.

[Kent Shootwell]

Cross drilled percussion nipples have been around since the late 1970s call "Hot Shot Nipples" by Michaels of Oregon. Designed by Dan Pawlak, the inventor of Pyrodex. Claims were " laboratory tests found that these nipples give more consistent muzzle velocity and better accuracy." Also prevents hammer blow back. This info is from an old "Gun Digest". I've used them on rifles but can't say I found them better or worse then any other good quality nipple.