Patent Breech vs Drum & Nipple

[SR James]

I'm getting ready to build a .45 halfstock, 7/8"x36" percussion rifle to be used primarily as an offhand target gun. The style of the rifle I'm building would normally use a drum and nipple, but while perusing the available parts, I saw the patent breech shown below:

I have rifles with drum & nipple, and patent breech, both percussion and flint and have had good results with all. But it got me to thinking...Can anyone think of any pros or cons to the above patent "drum" breech vs a conventional drum and nipple for an offhand target rifle (other than cost)?

 

[jtmattison]

Given the choice I would always take the patent breech over the drum. This is due to ease of cleaning as well as ignition reliability.

HD

 

[Cosmoline]

I had terrible problems with various Pedersoli patent breaches. The holes were too small and they would constantly get fouled. If I ever got one again I'd want to inspect the path the sparks are expected to fly down.

 

[J.D.]

IMHO, the patent style breech is stronger, and therefore, more safe.

However, using a 7/8" barrel in a 45 cal willgive you roughly .200 wall thickness. If you use a drum with a fine thread pitch. you should be fine.



God bless

 

[SR James]

Actually, my question is not so much about safety as it is about the performance of a patent breech in a match rifle, vs a standard drum. Any thoughts along those lines, like ignition, fouling problems, etc? Dawg, you mentioned ignition reliability...why would this style of patent breech be more reliable than a standard drum? I'm just trying to learn things I may not have thought of.

 

[J.D.]

IMHO, a drum is a drum, is a drum. The patent breech in the photo has a drum. Performance wise, IMHO, there shouldn't be any difference in this style of patent breech and a regular drum.

 

[Zonie]

IMO, if the hole in line with the bore is the same size as the bore J.D. is right.

On the other hand, the idea behind the original Patent Breech was that if a small chamber contained powder which was ignited first, the very hot flame from it shooting thru the main powder charge would be more effective in igniting that main charge.

To that end, Mr. Nock in 1787 created just such a chamber.
Because he patented it no one could use his design without paying him royalties.

Other builders, wanting to stay abreast of the latest ideas created the chambered breech that is commonly used on modern sidelocks and often called a patent breech.

The bottom line is, if the hole that is in line with the bore is much smaller than the bore it will be a chambered breech and in theory it will ignite the main charge more effectively.

Some tests have been done over the years and guns using these chambered breeches and the Patent breech do seem to create less fouling in their bores. Now, whether they are "better" is a matter that probably will never be resolved.

Knowing the problems some folks have with their chambered breeches with their long intersecting flame channels I personally lean towards the short connection that is typical of a side vented flintlock or a side drum percussion.

The breech shown in the photo is no doubt much sturdier than a screwed in side drum but that added strength has a weight penalty that goes along with it.
In the side drum and the breech shown in the photo both will have to be accurately installed so that they are fully supported by the lockplate.

This brings up the installation of this breech plug.

Because the projection is already "installed" its location is fixed. That means the lock will have to be located and installed based on the existing fixed drum.
This gives little room for error.
This is one of the reasons that building any percussion gun with a scroll breach or a Bar Lock is more difficult than building a percussion gun with a screw in drum.

A hole for a threaded side drum on the other hand can be shifted (before it is drilled), locating it to create a good alignment with the lockplate even if that plate is installed slightly high or low.

 

[grey8833]

SR James:

One advantage of the patent breach, in a target gun in particuliar, is that it is required if you want to get into the higher pressures of a 45 cal target rifle using "upset" bullets rather than a patch and ball. The pressures generated by an "upset" hard lead bullet in a shallow rifled barrel of a target gun will cause real issues if a "drum" breach is used (it could blow off).

Note what Zonie said. Having done a Hawken and a .451 Rigby target rifle, both using patent breaches (and the Rigby haveing a drip bar lock), getting that hammer face to land where it has to, is exacting and a pain in the where ever.

Mike F