Elkeater
45 Cal.
What is meant by "snail percussion lock"? Thanks
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snail definition
- Thread starter Elkeater
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hanshi
Cannon
A "snail" is a "coiled" appearing bolster integral with the breech and which the nipple screws into. A "drum" is a cylinder screwed into the side of the breech which is itself threaded to accept a nipple.
hanshi
Cannon
Here is a pic of a snail bolster.
Elkeater
45 Cal.
Am I to understand there is a snail and a drum type of breech?
Yup.
The "snail" as we use the term today, winds through the breech plug in a partial curve, leading to the bottom of the powder charge.
The "drum" is screwed into the side of the barrel and can contact the bottom or the side of the powder charge.
Is one better than the other?
:idunno:
Personal preference and that's it.
same as;
Is a Ford better than a Chevy?
Coors or Budweiser?
The "snail" as we use the term today, winds through the breech plug in a partial curve, leading to the bottom of the powder charge.
The "drum" is screwed into the side of the barrel and can contact the bottom or the side of the powder charge.
Is one better than the other?
:idunno:
Personal preference and that's it.
same as;
Is a Ford better than a Chevy?
Coors or Budweiser?
The snail style breech plug gets its name from the curved shape below the nipple. It doesn't really look like a snail but its shape is constantly changing like a snail shell.
A nice example of it is shown in the following link as # PLUG-PAT-15-5
http://www.trackofthewolf.com/List/Item.aspx/666/1
If your looking at that link you will also notice there are other style breeches that have the nipple support sticking directly out the side.
These are close to a "drum" style but they differ because the projection is a integral part of the breech.
A true "Drum" style screws directly into the side of the barrel just in front of the breech plug.
Examples are shown in this link
http://www.trackofthewolf.com/List/Item.aspx/809/1
A nice example of it is shown in the following link as # PLUG-PAT-15-5
http://www.trackofthewolf.com/List/Item.aspx/666/1
If your looking at that link you will also notice there are other style breeches that have the nipple support sticking directly out the side.
These are close to a "drum" style but they differ because the projection is a integral part of the breech.
A true "Drum" style screws directly into the side of the barrel just in front of the breech plug.
Examples are shown in this link
http://www.trackofthewolf.com/List/Item.aspx/809/1
Last edited by a moderator:
Elkeater
45 Cal.
Yes, spot on. Thanks guys for making it clear. Coors.
I don't know much about this but I thought the snail was generally considered superior to the drum because the snail had an angled path from nipple to powder charge- a straight line while the drum had the flare of the cap go into the drum and then have to go side ways into the powder charge. The snail was also dished to contain some of the flame of the cap so as to not char the surrounding wood. So I've been told...Is this correct?
I'm talking about a true snail, I think the T/C is a drum made to look like a snail.
I'm talking about a true snail, I think the T/C is a drum made to look like a snail.
ohio ramrod
75 Cal.
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The snail type is considered by many to be stronger since there is more metal to support the nipple and absorb the impact of the Hammer. The drum type has only the threaded part going into the barrel to support it. :idunno:
ohio ramrod said:
Not if the gunbuilder made the gun right.
The bottom of a properly installed side mounted drum is resting directly on the lockplate. It is not just screwed into the side of the barrel.
If the side mounted drum is resting directly on the lockplate, there is no stress caused to the threads when the hammer hits the cap on the nipple.
As for the supposed superiority of the snail style breech because of the angled path of the fire channel, I would disagree.
The flame from the nipple must make a right angle turn as soon as it leaves the bottom of the nipple with both the side drum design and the snail design.
After making that 90 degree turn, the flame from a side mounted drum only has to travel about 3/8 of an inch before it finds itself in the main powder charge.
After making that 90 degree turn, the flame in a snail style breech plug must travel at least 1/2 inch and with many, closer to 3/4 of an inch thru the small (often less than 1/8 inch in diameter) flame channel hole.
IMO, this distance is important because the flame looses a lot of its heat to the walls of the hole as it passes thru it.
Speaking of the flame channel hole, because the side mounted drum is only about 3/8 long, the powder in the main charge doesn't have far to go before it finds itself at the bottom of the nipple. It's almost there just by pouring the powder down the barrel.
With the snail (patent) breeches, making its way thru that (often) 3/4 inch long flame channel to the bottom of the nipple can be a problem.
If the flame channel has any fouling buildup or any oil, left from the last time the barrel was cleaned, it can form a dam that prevents any powder at all from ending up right below the nipple when the gun is loaded.
I much prefer the lock supported side drum to the snail style breeches.
Jason Lewis
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zonie is correct except that he forgot that on long range rifles the true drum is much too weak to sustain the pressures generated, thus a patent breech must be used since it's all one solid piece.
Rat Trapper
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I much prefer the snail over the drum as the snail is much stronger. Most of us who shot cap locks get in the habit of turning the rifle over and giving it a wack with the palm of our hand to help some powder move into the area under the nipple. Once that is done we load the ball.
Interesting thread. I have rifles with drums but always thought the patent breech was superior. I thought the ignition on the patent breech would be better although I've never had trouble with the drum. I have heard of some patent breeches that if not cleaned and scraped could have a fouling build up that would cause ignition problems.
I'm happier now with my plain old drum set up
I'm happier now with my plain old drum set up
Elkeater
45 Cal.
Does anyone know the distance from nipple to main powder charge on a T/C New Englander and a Lyman GPR?
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One of the reasons I like my underhammer rifle is because the nipple port is in the main charge. The hammer strikes dead on in line with the bottom barrel flat.It is about as reliable as a muzzle loader can be made to be and they are also used for slug guns sometimes with sealed ignitions.
I don't ever remember that gun misfiring unless I dry ball it.
PS. Does not a nipple at the end of a flash tunnel, filled with powder, have just as much pressure against it as it would if making direct contact with the main charge through the side of the barrel, given the same load density and ball weight? Mike D.
I don't ever remember that gun misfiring unless I dry ball it.
PS. Does not a nipple at the end of a flash tunnel, filled with powder, have just as much pressure against it as it would if making direct contact with the main charge through the side of the barrel, given the same load density and ball weight? Mike D.
Interestingly I'd say No.
Pressure as measured PSI, Per Square Inch,,
as it relates to the volume of the bore size.
Wouldn't the smaller size of the snail of a paten breech or the smaller size of the drum channel leading from the main charge carry only the fraction of that square inch it actually is?
Let's say a 1/8" hole off of a 1" bore that measures 80,000psi, wouldn't the pressure leaving the 1/8" hole be 10,000psi?
:hmm:
Pressure as measured PSI, Per Square Inch,,
as it relates to the volume of the bore size.
Wouldn't the smaller size of the snail of a paten breech or the smaller size of the drum channel leading from the main charge carry only the fraction of that square inch it actually is?
Let's say a 1/8" hole off of a 1" bore that measures 80,000psi, wouldn't the pressure leaving the 1/8" hole be 10,000psi?
:hmm:
Elkeater
45 Cal.
That is a head scratcher. In the Navy I helped in keeping the screw turning with a 1200 psi steam engine. We were told that a tiny hole in a pipe would cut your fingers off. Same pressure, more or less volume.
But in the barrel its very short time. :hmm:
But in the barrel its very short time. :hmm:
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I think the psi would be exactly the same, the difference is the area it is pushing against , which would be the same,ie, the base of the nipple, in both instances.
If that is true than would not an equally threaded nipple be just as secure in either case? Mike D.
If that is true than would not an equally threaded nipple be just as secure in either case? Mike D.
Ignoring such things as pressure losses due to high velocity gasses turning corners, the pressure in a closed interconnected system is the same everywhere.
The pressure behind the ball, the pressure against the breech plug and the pressure against the nipple are all constant.
Pressure in the US is usually measured in pounds per square inch. The actual force created on an object will depend on how many square inches of area it has that is trying to resist the pressure.
Putting this into common terms, lets say the pressure in the breech is 5000 pounds per square inch (PSI) when the powder ignites.
Now, if the breech plug has some 3/4-16 threads on it, it's effective diameter is 3/4 inch.
That size has a surface area of .442 square inches. 5000 psi X .442 square inches = 2,209 pounds of force trying to blow the breech plug out of the barrel.
A .50 caliber ball/patch combination has a effective surface diameter that is trying to plug the bore of .196 square inches. That results in a actual force of 5000 psi X .196 square inches = 981.7 pounds pushing the ball down the bore.
The 1/4 inch threads on the nipple have an effective surface area of .049 square inches.
.049 square inches X 5000 psi = a force of 245.4 pounds that are trying to blow the nipple out of the bolster/drum.
Ain't this fun? :grin:
The pressure behind the ball, the pressure against the breech plug and the pressure against the nipple are all constant.
Pressure in the US is usually measured in pounds per square inch. The actual force created on an object will depend on how many square inches of area it has that is trying to resist the pressure.
Putting this into common terms, lets say the pressure in the breech is 5000 pounds per square inch (PSI) when the powder ignites.
Now, if the breech plug has some 3/4-16 threads on it, it's effective diameter is 3/4 inch.
That size has a surface area of .442 square inches. 5000 psi X .442 square inches = 2,209 pounds of force trying to blow the breech plug out of the barrel.
A .50 caliber ball/patch combination has a effective surface diameter that is trying to plug the bore of .196 square inches. That results in a actual force of 5000 psi X .196 square inches = 981.7 pounds pushing the ball down the bore.
The 1/4 inch threads on the nipple have an effective surface area of .049 square inches.
.049 square inches X 5000 psi = a force of 245.4 pounds that are trying to blow the nipple out of the bolster/drum.
Ain't this fun? :grin:
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