Patent breech

[flint45]

I traded for a barrel for a future build,and it had a patent breech included.I understand they are supposed to be stronger than the typical breech plug,but I wanted to hear sone feedback from some more experienced builders.It is a Green Mountain .45cal,13/16th x 42 if that makes a difference.Thanks

[JDK]

Stronger?  Look over what you have and ask yourself, "In what other mechanical connection is a hollow plug stronger than a solid one?"

   Enjoy, J.D.

[Herb]

Where did you get a 13/16" patent breech?  The smallest I know of is 15/16".

[Majorjoel]

Also it would be important to know if your barrel is designed for percussion or flintlock ignition. If percussion, you definitely have a safety advantage going with a built in snail type bolster and not the standard solid barrel drum installation.

[smylee grouch]

Herb, I think TOTW sells 13/16 patent breeches.

[flint45]

It will be a flintlock,Tennessee/Southern Mountain style.I'm not totally sold on it,but it came with the barrel.I could get another breech plug and still use the barrel.I know they were used on some English guns,but they probably were not used on this type rifle.I'm not committed either way yet,just wanting some other opinions.Thanks...Mike

[Dennis Glazener]

It will be a flintlock,Tennessee/Southern Mountain style.I'm not totally sold on it,but it came with the barrel.I could get another breech plug and still use the barrel.I know they were used on some English guns,but they probably were not used on this type rifle.I'm not committed either way yet,just wanting some other opinions.Thanks...Mike
   

I have nothing against a patent breech in its proper place but I have never seen an original Southern Mountain rifle built with a patent breech. I believe I would reconsider doing that style with that breech unless you don't care whether its out of character with original rifles from that region.
Dennis

[Buffaload]

JDK,
Ponder this:
A patent threads into the end of the barrel and does not pierce it elsewhere, where a normal breech plug forces another entry perpendicular to the thread of the plug.  The proximity of these two intersecting threads, I believe,  would yield  a weaker situation.  So, in essence, I believe you are right in your remarks but there is this little problem of a vent or drum to get the gun to go off.  There's the rub.  Its not just the plug, its the entire mousetrap.
Your thoughts?
I have seen drums blown out and screws blown out but never a ruptured barrel patent or no,t where the plug was blown out.  Hmmm.

[JDK]

Your thoughts?

I only answered the question as asked.  The author made no stipulation as to whether the gun would be flint or percussion ignition.

In a flint ignition I feel there is no contest.  A simple, flat faced plug in combination with a vent hole is superior to the patent breech in strength.....especially if the flint breech is cast and not forged.  I also believe is is superior in ignition as it vents directly into the powder column.  There may be some argument for the true Nock patent breech, but not for the ones commonly available today.  After all, are they really "patent breeches" or merely plugs with a reduced powder chamber?

Percussion?  While I am not an advocate of the drum and nipple, I wouldn't hesitate to use it where proper and may actually trust it more than some cast patent breeches, unless those castings were subjected to testing and certified as void free.

A properly machined percussion patent breech may be superior in strength to the standard plug and drum, especially if the drum is threaded into a thin walled barrel that doesn't allow for much thread engagement.  I would bet that a drum threaded into a thick walled barrel is sufficiently strong enough to withstand some very high pressures, but know of no testing.

Not seeing them myself, I would venture to guess that the drums you've seen ejected were threaded into thin walled barrels and were either not supported sufficiently by the lock plate or were frequently removed and reinstalled or both.  Or perhaps the they were threaded with loose tolerances allowing the threads to corode.  I don't know.  Either way, I much prefer a drum to be ejected to a breech failure.

As far as breeching goes, no hollow plug is as strong as a solid plug of the same diameter and length.  I haven't seen it tested but I would wager that a barrel breeched with a solid pug and the nipple threaded properly, directly into the barrel wall will withstand much higher pressures than any pattent breech and that is why this arrangement is so popular with the big slug shooters.

I know, a lot of speculation here, but I don't have the means to test these theories.  Perhaps someone else will take on the task of performing test to destruction on some barrels for us.  Any takers???

The reality is that I don't think any of these are going to break off under normal shooting conditions.  Enjoy, J.D. 

[Dphariss]

Your thoughts?

I only answered the question as asked.  The author made no stipulation as to whether the gun would be flint or percussion ignition.

In a flint ignition I feel there is no contest.  A simple, flat faced plug in combination with a vent hole is superior to the patent breech in strength.....especially if the flint breech is cast and not forged.  I also believe is is superior in ignition as it vents directly into the powder column.  There may be some argument for the true Nock patent breech, but not for the ones commonly available today.  After all, are they really "patent breeches" or merely plugs with a reduced powder chamber?

Percussion?  While I am not an advocate of the drum and nipple, I wouldn't hesitate to use it where proper and may actually trust it more than some cast patent breeches, unless those castings were subjected to testing and certified as void free.

A properly machined percussion patent breech may be superior in strength to the standard plug and drum, especially if the drum is threaded into a thin walled barrel that doesn't allow for much thread engagement.  I would bet that a drum threaded into a thick walled barrel is sufficiently strong enough to withstand some very high pressures, but know of no testing.

Not seeing them myself, I would venture to guess that the drums you've seen ejected were threaded into thin walled barrels and were either not supported sufficiently by the lock plate or were frequently removed and reinstalled or both.  Or perhaps the they were threaded with loose tolerances allowing the threads to corode.  I don't know.  Either way, I much prefer a drum to be ejected to a breech failure.

As far as breeching goes, no hollow plug is as strong as a solid plug of the same diameter and length.  I haven't seen it tested but I would wager that a barrel breeched with a solid pug and the nipple threaded properly, directly into the barrel wall will withstand much higher pressures than any pattent breech and that is why this arrangement is so popular with the big slug shooters.

I know, a lot of speculation here, but I don't have the means to test these theories.  Perhaps someone else will take on the task of performing test to destruction on some barrels for us.  Any takers???

The reality is that I don't think any of these are going to break off under normal shooting conditions.  Enjoy, J.D.  

The patent breech was (Nock) made to increase reliabilty, velocity and make a better breeching all around. This it did.
Barrels with holes drilled in the side of them, be it for a vent, vent liner or percussion drum are not as strong as an undrilled barrel.
I have seen a 50 caliber GM b weight swamp with 5/8 threads and a "patent" breech drilled back to the the vent with a 3/8 ball end mill shot with 90 gr of FFF, patched ball, 90 gr FFF patched ball with no damage to the breech or the barrel. I suspect a drilled barrel would have survived as well if the hole were not too large.
Modesty prevents me telling exactly how this occured
Most if not all original slug guns are either patent breech or underhammer. It has little to do with strength given the wall thickness of a heavy slug gun. The underhammer is cheap and easy to make and works very well. This does not make it stronger. The thin barrel wall bullet rifles that shot heavy bullets and large charges of powder. 45s with 550 gr bullets and 100-120 gr of powder used percussion patent breeches. In a drum and nipple the drum is often the weak link. This is a plus for the shooter but may be deleterious to anyone on the drum side of the gun if the drum breaks off.
Also while a simple flat faces flint breech has tested as fastest the Nock antechambered breech is more consistent. Given it was developed for shotguns used in wing shooting consistency is a major advantage. The added velocity is also a plus.
If I can get the barrel breeched one of our Guild members is going to test various vents and breech faces for velocity.

Dan

[Dphariss]

PS unless shop made its impossible to get any patent breech over 1 1/4" so if making a 1 3/4" barrel and underhammer is the easiest way. I suspect this has been the case since Horace Warner's time.

Dan

[Acer Saccharum]

I don't believe a patent breech or other strengthens the breech. I'd be wary on a small diameter barrel to use something like the below. The barrel wall around the plug is thinner than if you used a slightly bigger than bore flat plug.

This a breech I made. It wasn't perceptibly faster or more reliable than the good old fashioned flat breech. But it required extra steps to clean it at the end of the day; if you want to call that an advantage you may. If you forget to load powder, the ball won't shut the vent off.

The design below worked fine, but would I bother with it again? no.

[JCKelly]

With respect to strength, I have seen one Thompson Center rifle blown apart with unpleasant results, due to loading with Unique. The patent breech stayed in place & in one piece, save the clean-out screw.

When these guns were used seriously, anything meant for a heavy charge had a patent breech. Drums tend to blow out.

[JDK]

......Drums tend to blow out.

Right.  Drums can blow out, but I question the integrity of the drum installation or maintenance in most of those cases.  I've seen an original gun double loaded and fired where the nipple blew out and the drum was left intact....and still is....and has been fired several times since with a new nipple.

But the original question was about strength of breeching, specifically solid vs. patent, not about drums, flash holes, nipples, etc.

If a test were conducted with a heavy enough barrel and an obstruction with enough integrity to overcome breech strength while venting through the ignition hole, I would still wager that the patent breech will separate at it's thinnest point outside the barrel before the solid plug strips its threads and is ejected.  I don't see either happening during normal use or even common accidental misuse, so perhaps the whole discussion is moot.

Enjoy, J.D.

[Dphariss]

I think people should make up a test barrel with a patent breech, flint or perc and then set about trying to blow it out.
Unless they play games with the design or use a very poor one, I believe it will be a waste of powder.
I would suggest that people interested in doing such things first borrow P.O. Ackley's two vol. set of books "Handbook for Shooters and Reloaders" (I think, they are in the shop and I am not) and read his experiments in which his chambered a junk 30-30 barrel to 30-30 Ackley Imp then shot it with the barrel turned out of the action to increase headspace  and so remove any support for the case head. With factory ammo the case would not set back to the breech face though once he backed the barrel away far enough the primer came out. Before this he had been forced to extent the firing pin to even reach the primer.
Its about surface area exposed to pressure, strength of material etc etc.
Dan

[Dphariss]

I think people should make up a test barrel with a patent breech, flint or perc and then set about trying to blow it out.
Unless they play games with the design or use a very poor one, I believe it will be a waste of powder.
I would suggest that people interested in doing such things first borrow P.O. Ackley's two vol. set of books "Handbook for Shooters and Reloaders" (I think, they are in the shop and I am not) and read his experiments in which his chambered a junk 30-30 barrel to 30-30 Ackley Imp then shot it with the barrel turned out of the action to increase headspace  and so remove any support for the case head. With factory ammo the case would not set back to the breech face though once he backed the barrel away far enough the primer came out. Before this point he had been forced to extent the firing pin to even reach the primer.
Its about surface area exposed to pressure, strength of material, how thick the material is where it must resist the pressure etc etc.
Dan

PS
DRY cases would not back to the bolt case or fail. Oiled cases would move back to the breech face. So even a 30-30 brass cartridge case, held tight to the chamber walls by the pressure, will contain quite a significant pressure level.

Dan

[JCKelly]

Has anyone here actually seen a patent/whatever breech fail?

Most of the burst guns I have seen were barrel problems. I saw one T/C used with smokeless, and a photo of another burst T/C where smokeless was blamed. In both cases the barrels blew to pieces ahead of the ?patent? breech, whatever it is T/C used, while the breech was not broken.

Considering the metallurgical quality of contemporary muzzle loading firearms, I'd not place solid vs patent breech designs high on my list of concerns.

[Acer Saccharum]

The biggest safety concern is the nut behind the trigger, not the patent breech.