chambered breech

[smart dog]

Hi,
Is there any real advantage to having a chambered breech on a flint gun?  By "chambered breech" I mean the typical octagonal breech with hook that threads into a barrel.  The breech has a powder chamber smaller than the bore of the gun. I believe the theory is that a small amount of powder falls into the chamber when loading and the rest of the powder and ball sits above it.  Flash from the pan ignites powder in the chamber which creates sufficient heat to explode the main powder charge instantaneously. That instantaneous explosion creates more force behind the bullet compared to powder ignited at the back corner through a small vent hole against a flat breech plug and that burns more slowly. What I describe is NOT Nock's patent breech just the typical breech sold today.  A disadvantage I can foresee is that the small powder chamber means thicker barrel wall, thus a longer vent hole and slower initial ignition. Perhaps a "white lightning" liner would solve that.  Then there is the issue of the the small powder chamber clogging with fouling and also being more difficult to keep clean.  Nock's breech is more complicated and has a little horizontal antechamber behind  a much bigger powder chamber. At one end of the antechamber is the vent hole and liner and at the other is a large clean out screw that enables the antechamber to be drilled perpendicular to the bore and across the breech and also allows access to the chamber for cleaning.

dave

[Gary W.E.]

My last rifle barrel had this chamber and it was a pain to keep clean during a match. I saw no true benefit to the chamber that made it worth having. I will never purchase another barrel that has one.

[smylee grouch]

This sounds like a good topic to run a series of test on. Same barrel with a flat flint style breech, Nock's breech and the one you suggest. Run about 10 shots through of each breech style with the same powder charge through a chronograph to see if their is any advantage speed wise. Also have Pletch time the ignition speed of each to see if one is faster or more consistent.

[D. Taylor Sapergia]

I've used this patent breech plug on several flint Hawken rifles, solely for their hooked and standing breech tangs.  I have always used bores of .50 cal + and run a ball end mill into the chamber to enlarge it, make it perfectly polished, and give the end of the chamber a 1/2 round end.  After cleaning such a breech for years using the tepid water pump/bucket system, the plug is still polished without blemish.  Ignition was instantaneous and there was never an issue with fouling interfering with ignition....the beauty of the hooked breech system!

[smylee grouch]

This patent style breech system sure has it's lovers and haters. Those who dislike it say it's too hard to clean and fouls up causing misfires. I'm thinking that a lot of those folks are using too thin of patch or a poor lube and maybe cleaning between shots. Gosh in 30+ years of shooting several of these types of equiped guns I have had no such problem unless I loaded with poor lube/too thin of patch or cleaned between shots. As for cleaning, as has been mentioned, forced water will flush them out and all thats left is to run a dry patch in and out of the anti-chamber. This has been my experience any way.

[Pukka Bundook]

I have wondered about these patent breeches.

We read we get faster ignition, but honestly I can't see it myself.
Not the modern kind, but I have a flint double fowling piece made 1811 or 12, and it has a long narrow breech, which opens up where the touchholes are.  It can go off fast, but it flashes in the pan more than any other. I maybe don't load it right, and plan on digging it out and re-trying it.
FWIW, a concave breech face is better than flat, as mentioned above,  it cuts down on recoil and seems to get a faster burn.  For me, this is good enough.

[Scota4570]

-Your vent liner or liner threads,  won't interfere with the cleaning patch or pull it off??  I have gone in with a rotary stone to make the liner match the contour of the bore. That may be unnecessary,  I just don't like the liner blocking the cleaning jag. 

-IF you dry ball you will not have any trouble putting powder under the ball to shoot it out.  I do dryball once in a while when my mind is wandering so, for me this is significant advantage. 

Just don't make the chamber narrow.  Make is as large as is safe.  The narrow ones like on Hatfields are a pain in the neck. 

[Mike Brooks]

I have noticed that with that style of breech shotguns tend to shoot denser patterns.

[Bob Roller]

I've used this patent breech plug on several flint Hawken rifles, solely for their hooked and standing breech tangs.  I have always used bores of .50 cal + and run a ball end mill into the chamber to enlarge it, make it perfectly polished, and give the end of the chamber a 1/2 round end.  After cleaning such a breech for years using the tepid water pump/bucket system, the plug is still polished without blemish.  Ignition was instantaneous and there was never an issue with fouling interfering with ignition....the beauty of the hooked breech system!

According to T.K.Dawson who did a good bit of research on the Nock system and patents,
this "Antechamber" breech system was used with limited success when the quality of powder
then available was variable from superb down to,as T;K said "Absolutely wretched". The idea
of this particular patent was to enable a jet of fire to hit the main charge abruptly and enhance the
performance of any particular load. He also said that is now (1968)hard to prove and other than
making a hooked breech available it has no real or perceivable advantage now.To see if this
breech offered any advantage then some old and known to be deficient powder would have to be
found and tested.
    Taylor's idea of a ball end mill is a good one and I did this on a 58 caliber flintlock rifle I made
and on a current 50 caliber half stock that is started but may or may not be finished by me and I
still must cobble together a lock for it.

Bob Roller

[flehto]

My caplock rifle has a so called patent breech and it works fine....although it has keys which allow a bbl soak in a bucket of hot water.

W/ a flintlock, I think it's an unnecessary complication especially if the bbl isn't removed for cleaning.  A flat faced plug is as simple as it gets and  is easy to clean w/o bbl removal, so why complicate an already simple system?......Fred

[bob in the woods]

Taylor..I think your comment should be amended to " the beauty of a patent breach that's had it's chamber enlarged "    My experience has been that used as they typically come, they are a real pain.

[smart dog]

Hi Richard,
The idea behind the patent breech as I understand it was not fast ignition. The stepped breeches and Nock's breech with the antechamber wall thickness at the vent very thin were meant to speed ignition. However, the simple powder chamber was meant to just explode the main charge instantly giving the powder more force. In fact, the theory goes back to the early handgonne days when powder was really poor. Nock patented his breech as a solution to slow ignition in these chambered breeches. However, today, with modern powder and white lightning vent hole liners, I suspect Nock's breech is unnecessary.  Mike B provided some evidence that the chambered breeches may make guns shoot harder with more force.  I am building a late flint English sporting rifle (1810-1820) and am considering having the barrel maker make a chambered breech but I want to make sure that it is worth it and that it presents no problem when shooting or cleaning. I know I can make a fine rifle with a flat plug that shoots really well so I want to make sure complicating things by using a chambered breech won't result in unintended problems.

dave

 

[smart dog]

" A flat faced plug is as simple as it gets and  is easy to clean w/o bbl removal, so why complicate an already simple system?......Fred"

Hi Fred,
That is why I am asking if there is a noticeable advantage.

dave

[Bigmon]

Just seems to me the touch hole would have to be "longer" and that the longer it might be the slower and the more chance for the dreaded flash in the pan.
Not hard to clean a flat simple breech plug.
I would love to be able to remove to clean barrel.  But no one has mentioned the pins and damage that can cause each time removed?

[varsity07840]

I have a flint Hawken with a patent breech that has given me fits on and off for years. The problem was powder bridging at the mouth of the chamber, which prevented it from filling up with powder. Hang fires would occur. As noted above, a ball grinder used on the mouth of the chamber to give it a profound chamfer followed by polishing helps. Nevertheless the powder doesn't seem to pack up as tight against the touch hole as opposed to a standard flint set up. More often than not, I pick some priming into the chamber.

[ericxvi]

I've used the patent breech system on four rifles so far with no problems. These, I have made myself, all were .312 ID. Cleaning is with a 30 cal brush with a cleaning patch wrapped around where there's excess at the front to wipe the bottom of the hole.
  The main advantage for me is I can locate the lock wherever I want.
 I have never had fouling problems wiping between shots, or hang fires, but then I have never tried any with an ID less than .312.

[smart dog]

Hi Eric,
Thanks for that post.  That is one clear advantage of the chambered breech.  The other is that it may shoot harder for a given powder charge. The disadvantage is that if not set up right, fouling can be a problem.

dave

[Pukka Bundook]

Smart dog Dave,

I think if I were to make any sort of patent breech, I'd go with Nocks design, simply because it is easier to ensure  plenty of powder at the touchhole.
I would however, make the narrow neck a bit  wider, to readily accept the powder into this anti-chamber.
 The Nock with clean out screw in the off-side seems the easiest method to me.

Otherwise, a plain simple breech with a bit of a curve to the plug face seems to serve as well. 

Ideally we should run Peter Hawkers tests again....the same barrel with different breeches screwed on. See if we with todays powder get the same results!

[Joe S]

These things are easily measurable. I don't have any data on a patent breech, but I do have data on flat vs hemispherical breech plug faces.  For a .50 caliber barrel, a hemispherical breech plug face will increase muzzle velocity by about 100 fps.

Here’s the data:  http://americanlongrifles.org/forum/index.php?topic=37246.msg357598#msg357598

And the hemispherical breech plug I tested:

[Mike Brooks]

I have experience with two SXS shotguns with chambered breeches. (not a Nock breech) One an antique 18 bore flint gun and the other a 14 bore flint gun I made. Chambers on the antique was probably about 5/16" and slightly tapered, the other 14 bore was a bit larger than 3/8" and slightly tapered, both were maybe 3/4" deep? Can't remember. Both had a "rolled" edge at the mouth. I believe it was the taper and the rolled edge that make these work so well. Both have flawless ignition.
 Chambered breeches for me worked excellent as described above for shot gunning, Never ran them past a chronograph so I have no idea if there was an improvement in velocity or not. I have no idea or experience shooting RB with a chambered breech.

[L. Akers]

About 1970 I invented a flint chambered breech and installed it on my rifle.  I also designed my own touchhole liner and the breech incorporated the liner.  Having no data but imperical and  familiarity with my rifle, the ignition speed was very noticibly faster and recoil was greater.  Some time later I discovered Nock had patented my breech 200 years earlier.  Chamber's White Lightening is the closest to my touchhole liner design.  I have had no trouble with fouling in my Nock or Manton breeches.  The higher pressures and temperatures seem to reduce chamber fouling to practically non-existent.  Since then I have made and installed many Nock breeches and the usual response of a customer upon firing is "Wow! That's fast!".

[smylee grouch]

Pukka has a good idea in that it would be great if we could do Hawker's tests over with our modern powders but IMHO the results would be quite like Hawker,s tests in that the chambered breech would shine over all others. One important thin g that some omit when installing or building them is to have that hole too small and then the powder has a better chance to bridge up and not make it to the bottom of the antechamber.

[rich pierce]

I always knock my buttstock sideways after pouring powder down to settle it.  Just how I was taught.  It might help powder fall into the antechamber.

[smart dog]

Hi and thanks for all the responses,
After reading L. Akers post I just want to make sure we are all on the same page.  To make a "chambered" breech I would drill a hole for the powder chamber into the threaded plug section and into the solid octagon breech.  That hole might be tapered, round bottomed, and have a funneled or rolled edge at the beginning of the threads.  I would then drill a hole for a white lightning liner into the octagon section positioned at or near the end of the powder chamber.  I suspect the diameter of that chamber is important because if too large encompassing a large portion of the powder charge, you really haven't gained anything over a simple flat breech plug.  If too small, fouling and cleaning may be a problem.  If just right it encompasses only a small portion of the charge sufficient to create a very hot flash into the main charge such that it is ignited almost instantaneously. 

Now if I was making a Nock's patent breech, I would drill a powder chamber as before but larger to contain much of the total powder charge.  Then behind the end of that chamber, I would drill a large hole through the octagon section from one side to the other.  The hole would be sized for threading a white lightning liner on the lock side and a 5/16- 32 screw on the other.  Then I would drill perhaps a 3/16" diameter hole at the bottom of the powder chamber and into the hole drilled across the octagon section. That hole would need to be just large enough to always allow a small amount of powder to enter the cross chamber (antechamber).  That small amount of powder is enough to create a hot flash when ignited that ignites the main charge in the powder chamber almost instantaneously. 

dave

[rich pierce]

There’s a part of the discussion of patent breeches that talks about fast ignition.  It may be faster but the explanations confuse me.

With a plain flint breech ignition proceeds like this, methinks:
1) Priming lights and flashes
2) Flash passes through vent
3) Main charge lights and explodes


With a patent breech, I think I am hearing the process goes like this:
1) Priming lights and flashes
2) Flash passes through vent
3) Charge in antechamber somehow is not functionally part of the main charge, but it explodes
4) The main charge, which is somehow functionally separate from antechamber powder, explodes faster because a jet of heat shoots up the middle of it

I don’t doubt the shape of the antechamber could impact pressure and thus velocity.

I guess until/unless we could use a transparent barrel we don’t really know.  I guess I have to wrap my head around that there’s a difference in time between when the back and front of charge ignite.