Breech plugs, lessons learned

[Bsharp]

I built this smoothbore in the late 80's. 7GA, kind of big, but the lessons are the same.

When trying to shoot patched round balls, it would blow the center out of the patch.

Breech is 1/4" x 1.1/4" long. See the problem?

I opened it to 5/16, with a heavy counter sink......al don thru the bore. It was better.

Now.......trying to shoot birdshot loads............No consistent pattering.

The old 'venturi', jet effect is at work on the first card. [my thoughts]

I tapered a 3/4" drill, using an extension and guide. opened the hole up to 3/4" x 1" of taper[ish].

Guess what? I now have pattern after pattern!

I wonder how many other guns suffer poor breeching?

[bob in the woods]

I won't have anything to do with reduced from bore size breeches.  I've seen just too many of them having failures to fire at various matches . With a standard breech and decent touch hole, I've never ever had an issue.  It's also a heck of a lot easier to clean the gun.

[Daryl]

I think I understand. The breech was a patent-type breech with  only a 1/4" hole back to the flash hole from
where it seated against the end of the barrel.
Actually I don't see that as a problem except maybe with fouling after repeated shots.  I find the enlarging
of this hole changing the characteristics of the shooting, to be quite interesting idea indeed.  The English had
some weird breech shapes, that were said to aid patterns etc, example the Nock breech.
I can see no reason the 1/4' hole at the bottom of the barrel, top of the breech would be responsible for blowing the centre out
of the patch, or effecting a pattern.  Maybe it does, however, the powder also sits in the full bore ahead of the breech plug, so all
would be ignited before anything moved, thus the 'force' against wads, or patched ball would be full bore sized.
5/16" from 1/4" is not much of a change & yet you had a change.
Interesting indeed.
Many English gun breeches, with patent-type breeches and bolsters, had a cone shaped entrance to the bore at the end of the threads,
 roughly 1/2" to 3/4" long.
The Blissett breeched barrel section I have has that shaped patent breech.

[smylee grouch]

Some people with those breeches have problems with the powder "bridging up" right in front of the breech which can cause missed fire. Enlarging that hole, putting a cone on the face and or dropping your powder down the bore a little slower might help get that powder down into that chamber. Those breeches do take a little more time to clean but if you dry ball a shot you have an ample amount of room to get some "pop out" powder in through the vent or nipple hole.

[Daryl]

There was a chamber similar to this (chambered), used in military rifles of Austrian make when using naked round balls or slugs.
The powder charge matched the 'resess', and the shoulders of the hole were used to enlarge the ball or bullet, by 3 strokes of the
rammer.(ramrod)
This chamber/rifle, was called the Delvinge, which sounds quite French to me. The other chamber, had a post sticking up from the middle
for ramming the ball onto so slug it up to engage the rifling. This was called the Tige.
The US army used both of these systems at some point in history.

[alacran]

Just a question, in what state is a 7  gauge legal for bird hunting?

[Bsharp]

Just a question, in what state is a 7  gauge legal for bird hunting?

In Michigan. for Turkeys. Not waterfowl.....#4 shot or smaller.

[kudu]

I find it interesting but have no explanation for  cause and effect for blown patches or poor patterns.

I build my guns and all have the plug as "flat as a pancake" I shoot flintlocks so if you/I dry ball it has to be pulled the ball sits in front of touch hole, cant get powder in behind unless you move it forward a little.

I Never Dry Ball though !! 

[kudu]

Just a question, in what state is a 7  gauge legal for bird hunting?

In Michigan. for Turkeys. Not waterfowl.....#4 shot or smaller.

You Live in Michigan ? you should try shooting the "Round Robin" I wrote a article explaining the rules and history of the shoot (Its A 6 shoot Smoothbore/Tradegun aggregate starting the first of the year) it will be in the Newsletter for the MSMLA next month May/June Issue. Just google MSMLA and follow links.

[Bsharp]

Just a question, in what state is a 7  gauge legal for bird hunting?

In Michigan. for Turkeys. Not waterfowl.....#4 shot or smaller.

You Live in Michigan ? you should try shooting the "Round Robin" I wrote a article explaining the rules and history of the shoot (Its A 6 shoot Smoothbore/Tradegun aggregate starting the first of the year) it will be in the Newsletter for the MSMLA next month May/June Issue. Just google MSMLA and follow links.

Is this birdshot [flying] or round ball shooting?

[Daryl]

Just a question, in what state is a 7  gauge legal for bird hunting?

In Michigan. for Turkeys. Not waterfowl.....#4 shot or smaller.

You Live in Michigan ? you should try shooting the "Round Robin" I wrote a article explaining the rules and history of the shoot (Its A 6 shoot Smoothbore/Tradegun aggregate starting the first of the year) it will be in the Newsletter for the MSMLA next month May/June Issue. Just google MSMLA and follow links.

We had a shoot sort of what I think that is.  Many targets were patched or bare round ball - your choice - as well as a clay bird or two thrown, for shot, so you had to be able to shoot both
from your smoothbore.

[kudu]

Just as Daryl guessed 12 gongs for 120 points 4 clay birds for 40 points. 3 throws with knife while holding unloaded gun in opposite hand , 3 throws with hawk gun in hand . 30 points total . Firestarting with flint a steel , must have flame in 30 seconds or less 10 points.
Total 200 possible
No pacing for hawk or knife.
All loading from the pouch, all items to be carried on person ,period dress required.
Seems complicated but its really not and its a ton of fun!!

[Daryl]

That sounds like fun- are ferro rods allowed? 

[kudu]

That sounds like fun- are ferro rods allowed? 

No ferro must be flint against steel and no you cant use your gun lock I tried ,the power's that be said NO
Fine Tow/Flax and some char cloth is what everyone around here uses. I usually can get flame in 15-18 seconds. Had a shoot in the fall where you had to place your flint and Steel in basin of water and on "GO" get them out and dry and get flame . Old Native American I shoot with sometimes got fire in 13 seconds man was he fast!! Of course you got your fire "Nest" set and ready just waiting for a spark and some aggressive Blowing.

[Dphariss]

I have a rifle with a Nock breech and it works really well so long as good quality powder is used, Swiss. If I use a powder that creates flakes of fouling in the bore one will fall over the passage in the breech and require putting priming through the vent to fire the rifle.
I sent a block of steel bored to a Nock configuration and threaded as a breech plug to Larry Pletcher and he found that while it was not the fastest breech ignition wise it was the most consistent in time. Which in the British world of wing shooting would have been important.
Here are a selection of breech designs used by the English in  flint guns. From "The Gun"  W Greener 1835

https://www.facebook.com/media/set/?vanity=100000127103372&set=a.4561160213898170

[Dphariss]

I might also point out that my version of the Nock Patent does not have this shape cavity but is simply hemispherical.

Dan

[Bsharp]

Dan, that is what I use now on my underhammers, a hemispherical as big as possible.

But, they are less tan 3/4" deep, depending on caliber.

Some times even with some side taper.

[redheart]

If I had my choice, I think I'd go with the Wilkinson's Parabolic Breech !

[Bsharp]

If I had my choice, I think I'd go with the Wilkinson's Parabolic Breech !

Very interesting design.

[smylee grouch]

I have a Wilkinson' s Parabolic breech on a 58 half stock flinter. The muzzle velocity increased by 100+ fps with the same charges after I created the inner cavity of the anti chamber. It does take a little extra care in cleaning but only about an extra min. or two.

[Leatherbark]

I made me a 12 gauge percussion single barrel muzzleloader from spare parts a few years ago.  I used a 30 inch full choke modern (sort of) Savage single shot barrel (Pokestalk)  After sawing off the lug the 12 gauge 2-3/4 inch chamber is the perfect diameter to tap for a long 7/8 x 14 breechplug made from a grade 8 bolt.  I drilled a 40 caliber communication hole into the long breech plug close somewhere around 1-1/2 inches deep to connect with the hole in a nipple drum.  THis allowed full engagement of the drum threads into the breech plug.  I used an 1803 Harpers Ferry rib with steel thimbles to make a very light halfstock full choke shotgun.  Although I haven't patterned it I have used it in our local trap matches.  Some have commented on how some of my clays have disappeared into oblivion upon firing.........I do need to pattern the gun.............Bob

[Bsharp]

Bob, do you still have the forcing cone?

I have a 20 gage barrel that I plan to do this with.

[Dphariss]

Dan, that is what I use now on my underhammers, a hemispherical as big as possible.

But, they are less tan 3/4" deep, depending on caliber.

Some times even with some side taper.

Don King used to use a lot of cupped breeches. My 38" barreled DK flint Hawken makes 1900 with 100 gr of FFF. The breech design can have an effect on velocity.
I like the Nock breech. Its not faster than my DK Hawken or any FL with a good lock and a decent. It does give 1600 fps  to a one ounce ball with 140 gr of FF Swiss in a 30" barrel.

Dan

[Dphariss]

I usually use a hemispherical "cup" as Don did if I do one. In constructed breeches I make them however I need to for the application.
The Nock is deeper than hemispherical

Dan

[Bsharp]

Like archery, too many are worried about speed. If you don't have accuracy, you don't have $#@*!

I have always like big bores with short barrels. If you need more speed, get a longer barrel.

But if you can pick up some speed and accuracy with just a breech style, I am all for that!

I would have to build the parabolic design in two pieces, and jam them together.