Reducing / Eliminating Cap Jams in Open Top Colt replicas

[J-Bar]

I'm late to the party, had to be away from the computer for a few days, and for some reason my dumb smart phone will not always allow me to post.

I suspect the old percussion caps were tougher than those available today. I got some old RWS caps in a bulk trade, no telling how old they were, but every one of them had to be pried off the nipples after firing---no jams from blowback with those things! If any of you cartridge/cap collectors have some left over from the 1800s, maybe you could experiment with a couple and see how well they stay on the nipples. I don't know when the Manhattan modification was invented, but I think Sam Colt would have tried to correct the problem if blowback jams occurred as frequently then as they seem to now.

By having a hammer to nipple clearance of .005" and no sharp edges on the hammer face I have reduced open-top cap jams to near zero. Carefully file the hammer face until the correct clearance is obtained. Then file away all the sharp edges on the hammer face. This repair can be done with the revolver completely assembled. Protect the frame with tape to prevent any scratches from the file.

Smokin' Joe, a technical question: how do you go about measuring the gap between the hammer face and nipple so precisely? I tried to get a feeler gauge in there but the long hammer nose covers the top of the nipple and I can't figure out how to get that measurement accurately. Thanks if you can explain or post pictures.

 

[midland man]

he maybe using plastigauge!

 

[Crawdad1]

I agree J-Bar, the older caps were made of tougher material and did not splinter like they do today.

 

[drobs]

So now I'm looking for small threaded pins:


This might work:

http://usaknifemaker.com/knife-handle-parts/handle-hardware/corbys-rivets-loveless-others.html

Might as well tap / thread the hole:



I plan to add one of these mounts to my M92 AK pistol - so some tap practice might be a good idea.

 

[TheRodDoc]

There really isn't much difference in the metal part of the cap early to now. The big difference (And the real problem) is the powder charge in them. Cap companys have been adding more power since the late 80's. The reason the caps blow open and off the nipple is because all the gas the cap is producing can't be forced through the hole in the nipple as fast as it is produced. So the excess has to go somewhere and that is out under the cap. This is what blows the cap open. It also blows the hammer back some at the same time letting the cap fall off and maybe into the action. And it happens before the main charge ignites.
The charge in the caps needs to be reduced to stop the problem.

 

[J-Bar]

There really isn't much difference in the metal part of the cap early to now. The big difference (And the real problem) is the powder charge in them. Cap companys have been adding more power since the late 80's. The reason the caps blow open and off the nipple is because all the gas the cap is producing can't be forced through the hole in the nipple as fast as it is produced. So the excess has to go somewhere and that is out under the cap. This is what blows the cap open. It also blows the hammer back some at the same time letting the cap fall off and maybe into the action. And it happens before the main charge ignites.
The charge in the caps needs to be reduced to stop the problem.

I respectfully disagree. I routinely practice draw and fire in my garage using caps only (no powder or ball in the chambers) on my 1851 Navies, and do not have any hammer blowback or cap jams. (I use caps to trip the timer as well as to protect the nipple.) And these guns have Treso nipples with smaller flash holes so the pressure inside the nipple from popping the cap should be higher than with factory nipples. Furthermore, just about everyone has shown that blowback can be made worse by increasing the powder charge in the chamber.

I don't know how much the propellant charge in the cap itself has varied from 1822 to now, but I am sure it is the pressure generated by the powder in the chamber that is the problem, not the cap.

 

[midland man]

I respectfully disagree. I routinely practice draw and fire in my garage using caps only (no powder or ball in the chambers) on my 1851 Navies, and do not have any hammer blowback or cap jams. (I use caps to trip the timer as well as to protect the nipple.) And these guns have Treso nipples with smaller flash holes so the pressure inside the nipple from popping the cap should be higher than with factory nipples. Furthermore, just about everyone has shown that blowback can be made worse by increasing the powder charge in the chamber.

I don't know how much the propellant charge in the cap itself has varied from 1822 to now, but I am sure it is the pressure generated by the powder in the chamber that is the problem, not the cap.

amen!!

 

[TheRodDoc]

You don't have caps blowing apart because the chamber is open. Totally different then when loaded with powder and ball.

Watch these videos carefully. use the settings to slow them down. They show what I said.

 

[J-Bar]

That is great slow motion photography, and certainly one can see the "bounce-back", particularly on the Remmie in the top video. I am not yet totally convinced however that it is simply because the chamber is "blocked". That powder is burning in there and increasing pressure quickly before gasses are seen at the barrel-cylinder gap, and that may be contributing to the hammer kicking back.

So I will conduct my own experiment tomorrow, plugging up the chambers with something other than powder, and see how much if any blowback happens with just the cap charge. I don't have the means to do photography like that, but I will report how many caps get blown back off the nipples. It will be fun to see what happens.

 

[TheRodDoc]

Here is a ruger old army. Same thing.

By the way J-Bar, You said you were sure it was the main charge, not the cap.

AT 022 Be sure to slow it down to 0.25 setting.

 

[45 Dragoon]

Hmmmmmm . . . what I see in the videos is: the Remies hammer is bouncing off the frame. It's probably not contacting the nipple. The Colt hammer goes down, stays down.

Pros: The Remie can probably be dry fired (untill the frame starts to distort) and not damage the nipples.
The Colts hammer isn't blown back. The cap frags (at this point) are trapped.
The Colt may not be contacting the nipples and may be dry fireable.

Cons: Remies shouldn't be dry fired (it damages the frame and the nipples if there is contact).

Colts generally have a much too heavy mainspring and more often than not, cannot be dry fired. The trapped cap/cap frags can (and will) be dragged backwards to fall into the action. This happens because the safety slot in the hammer face is much wider than the 1st gen revolvers had, which allows caps/frags to be fired into the slot. The good thing is that a cap post will pull out any debris and arrest any blowback through the cap (whether cap charge or main charge) and allow a much reduced mainspring which will allow it to be a much easier handling revolver.

See how much sense a cap post makes in a modern replica?!

Mike

You guys type and post fast!!!
The ROA exhibits the same bounce that the Remie does. ROAs can be dry fired so I'm sure this is a bounce not a "blowback".

 

[Crawdad1]

I thought that the old caps were made of thicker copper whereas today they are made of thin brass.

 

[TheRodDoc]

Caps now are all copper as they were in 1800's. There was a time in the early 70's one company made some from brass for 4 or 5 years. It might have been CVA. I might still have some somewhere.

 

[J-Bar]

By the way J-Bar, You said you were sure it was the main charge, not the cap.

Yes, I was sure before I saw your videos, so you presented new information. I had not considered the effect of a full chamber versus an empty one. I don't know if I can complete the test today, but the question can be examined objectively. It's foolish to argue about something that can be tested experimentally. I will post results when I'm done.

 

[Smokin'Joe]

"Smokin' Joe, a technical question: how do you go about measuring the gap between the hammer face and nipple so precisely? I tried to get a feeler gauge in there but the long hammer nose covers the top of the nipple and I can't figure out how to get that measurement accurately. Thanks if you can explain or post pictures."

Point barrel toward ceiling with hammer cocked. Measure barrel to cylinder gap. Lower hammer and remeasure. As for the .005" hammer to nipple measurement I gave that is the minimum distance I use. You can easily go to .010" with no problem. If you measure the thickness of chemical compound in a cap you might be surprised. I have measured as much as .040" of chemical compound in caps.

 

[J-Bar]

I performed my garage experiment today, made a video of the results, and published the video on YouTube for you all:



The question was, do modern percussion caps generate enough pressure by themselves to cause cap fragments to be blown back into the hammer channel?

I used my Uberti 1851 with Treso nipples and and seated a .380 lead ball on a chamber full of cornmeal. I tested the "new, hotter" Remington #10 percussion cap first, then some CCI #11 Magnum caps. Neither brand of caps caused cap fragments to blow back off the nipple, much less into the hammer channel. I'm satisfied that caps do not generate enough pressure to blow themselves back off the nipple and into the hammer channel. Cap fragments in the hammer channel are caused by the hammer face dragging the spent cap off the nipple, or pressure from the main powder charge blowing backwards through the flash hole.

I have never owned an 1858 Remington, so I have no opinion on the possibility of the hammer "bouncing back" off the frame. I will trust the opinion of others on that.

It was an interesting way to spend a winter afternoon.

 

[drobs]

JBar, IIRC aren't Treso nipples vented - meaning they have a small hole on the side of the nipple?
I wonder if you would see any difference with a factory non-vented nipple?

 

[J-Bar]

Treso nipples do not have side vents but they have a much smaller flash hole than factory nipples, which reduces blowback from the powder charge. Slix-Shot nipples have the side vent holes.

 

[midland man]

I performed my garage experiment today, made a video of the results, and published the video on YouTube for you all:



The question was, do modern percussion caps generate enough pressure by themselves to cause cap fragments to be blown back into the hammer channel?

I used my Uberti 1851 with Treso nipples and and seated a .380 lead ball on a chamber full of cornmeal. I tested the "new, hotter" Remington #10 percussion cap first, then some CCI #11 Magnum caps. Neither brand of caps caused cap fragments to blow back off the nipple, much less into the hammer channel. I'm satisfied that caps do not generate enough pressure to blow themselves back off the nipple and into the hammer channel. Cap fragments in the hammer channel are caused by the hammer face dragging the spent cap off the nipple, or pressure from the main powder charge blowing backwards through the flash hole.

I have never owned an 1858 Remington, so I have no opinion on the possibility of the hammer "bouncing back" off the frame. I will trust the opinion of others on that.

It was an interesting way to spend a winter afternoon.

and again amen!! thanks j-bar!

 

[TheRodDoc]

Nice video.
It does show what I said about the caps blowing apart and even some off the nipple. Reason being what I said about the gas produced can't all get into the chamber. I have found that the charge in the caps must vary because once in awhile a cap will remain intact on the nipple and I have to use something to pick it off.
Back in 1972 when I got my 1851 Colt, Remington and CCI 10 caps would both work well with the gun. Some time in the late 80's neither brand would fit in the revolver. They both stuck out farther off the nipple and would not let the cylinder turn because they hit the back shield. When I finnally decided it was more powder in the caps causing the problem and those companys were going to keep making them that way, I had to alter the nipples. I had to use the lathe to shorten the cone part of the nipple a fair amount.
After that I noticed that most of the caps were blowing apart which they had hardly ever done before with the older caps with less power.