is a breech plug necessary?

[zimmerstutzen]

small cannons have none. If I have a blind hole drilled into a piece of 4140 stock and then reamed, for a pistol barrel, will that suffice?

I figure if I leave an 3/4 inch solid at the breech, a plug will be unnecessary.

I have a piece of 2 inch by 11 inch 4140 and plan to make a one inch bore gun, with a 3/4 diameter powder chamber at the breech like mortars have.

Would a 1.25 bore be too large?

 

[Black Hand]

How do you propose to ream the barrel if you can't do the entire length?

 

[ohio ramrod]

It is not hard to ream a "blind hole". You just can't do it with a "square reamer. :hmm:

 

[widget350]

It should work just as well as it would with a cannon, but cannon mount to carriages much differently than barrels typically mount in stocks. The breech plug not only seals the barrel, but also provides a tang/place to mount a tang. There are many work arounds to this, of course, but something to consider. Also, if you're going flintlock, you won't be able to cone the inside of the vent, if that was part of your plan. Again, many other options.

 

[Birddog6]

Now it mounts has nothing to do with it, nor does the tang, nor a inside cone on the vent hole.

If you can ream the bore properly with a blind hole, then I see no reason you cannot do it with a solid breech.

The sole reason for a breechplug is because it is production efficient to have a thru-bore to work them barrel on the machinery, especially on long barrels. Blind reaming a 8" barrel is one thing. Reaming a 42 or 46" blind hole is an entirely dif. matter. Rifling one would be the same issue, as you would have to push the groove cutter out on each pull & if it is down in a blind hole against the groove, how do you move it out :hmm: when normally you would go out of the bore, adjust the cutter out & pull a new cut in that groove. (or that is how the old machines would do it)

Much easier to drill, bore, ream, rifle, etc. a thru hole in a long barrel.

A solid breech of substantial thickness would be stronger than one that is threaded in & thus relying on threads for the strength. If the bore wall thickness is thinner than the breech, the wall would blow out of the barrel before the breech end would move. Pressure will move the least resistance.

Now exactly how much breech thickness you need for your bore dia ? I can't tell ya. Need a guy like Zonie to figure the pressure vs mass needed, etc. General rule of thumb on most ML is you need at least the bore dia. in thickness for a breechplug. Most barrel makers have more than thickness than bore dia., but that seems to be the general consensus. I have seen some original old firearms with some short breechplugs....

Keith Lisle

 

[widget350]

I was assuming he was planning a smooth bore, and those were the only side issues I could think of - again, there are several options for approaching any of them. Think of handgonne or hackenbuchse (made very similarly to what is described) - many approaches to mounting, and just using barrel lugs would be an option as well. The idea is inherently safer than using a breech plug, as you pointed out.

Using a powder chamber, the bore size is less of a factor. It still needs to be within reason, but the chamber takes the majority of the pressure in firing.

 

[Greebe]

It would not be possible to rifle a blind hole style barrel. Barrel machines are made for through hole drilling, reaming, and rifling. I suppose you could make a smooth barrel with a blind hole but you would need a different setup which would not be worth it since there would be no pay off.

Besides how would you get a stubbornly stuck ball out that could not come out the muzzle if the barrel did not have a removable breech?

 

[Black Hand]

Another thought:
How would you be able to confirm that the bore is parallel to the outside of the barrel if a blind hole is bored? If it isn't, then sighting would be an issue and with a short barrel, a little difference over the length of the barrel will translate to a much larger difference down-range.

 

[widget350]

I happen to know a bp cannon maker who built a rifling machine capable of rifling thru or blind holes in straight or gain twist to handle bores from 1/2"-2 1/2" x 54" long. Also, drilling a straight blind hole is possible. Most cannon makers I know do so on a lathe. It's definitely possible to do, but it takes a lot of work and the right machinery.

 

[Greebe]

I could see how a cannon could perhaps be rifled since it is such a large bore, but I doubt that it could be done with a small bore.

 

[widget350]

Note the size range I said the rifling machine is designed for. Zimmerstutzen said he plans on a 1-1.25" bore. The machine I know of specifically is capable of .5-2.5". .50 cal is not at all unusual for a rifle. I can pm you a reference for this if you like.

 

[tenngun]

The very first hand gonnes were made with a solid breach. The iron stok cut like a daisy with a solid center then the leafs folded up and forge welded around a mandral