Was watching "Building Muzzleloaders"

[HardBall]

In this video, James Trupin built his own Knocks Patent breech on a flintlock: With the breechplug installed, he marked the flashole, then drilled through the barrel, halfway into the breechplug. Then, removed the breechplug and drilled a hole into the face of the breechplug, mating with the flashole, drilled hole, creating the anti-chamber. He then champhered the face of the breechplug. After putting the breechplug back in, he installed the touch hole liner and called it a "knocks" breech.

Is it really as simple as this? Is it OK to drill into the breechplug? Wouldn't this weaken the breechplug somehow?

 

[Zonie]

I don't see the vidio, but to answer the question "..Wouldn't this weaken the breechplug somehow?" the answer IMO is, as long as you have about 1/8 inch of wall between the holes and the outside, the breechplug will be strong enough to withstand any pressures produced by any black powder charge.

We live in a world where we have access to well made steel which is stronger than any of the wrought iron materials used in the days of muzzleloading.

Threaded things are also strong enough to withstand BP pressures provided they have a thread length which is about as long as the diameter of the thread.
For instance, a #10-32 male thread is about .190 diameter. If it is 3/16 long (.187) it is more than up to the job of containing BP pressures.
In fact, at 20,000 PSI pressure, there is 567 pounds of force trying to blow the threaded #10-32 screw out of the hole. (20,000 PSI is about as much as one would expect to ever see in a BP rifle and then only if it was a small caliber gun with a heavy slug for a projectile and a very heavy powder charge.)
Even with mild steel parts, a #10-32 screw can easily exert a force of over 1200 pounds when torqued to about 5 foot pounds of force, without failing.
What this boils down to is the "safety factor". In the example given, that would be 1200/567=2.11 or about 211%.

This safety factor is why the thread length can be shorter and it is still strong enough to function.
Things like vent liners and nipples often have 1/4 dia threads but have only about 3/16 of thread length and work just fine.

 

[HardBall]

...Not that I understood everything you just said :huh: I do get the picture that- yes it would be safe.

Thanks Zonie,

 

I had to do this with one of my guns, but I removed the plug first, drilled the hole for the liner, then marked the breech face with a pen...I figured that the threads would chew my drill bit to pieces. I then used a round file and chamfered the face until it matched the liner, then polished the face and chamfer with a Dremel armed with a polishing wheel and jeweler's rouge.

Ain't Jim's video great?

Stumblin

 

[HardBall]

I had to do this with one of my guns

Why did you "have" to do it? Was it because of the location of the lock in relation to the barrel?

Ain't Jim's video great?

It was a good video- explained a lot by watching instead of just reading books.

 

I "had" to do it because of the location of the touchhole in relation to the breech face, yes. In order to center the hole over the pan, it laid it squarely in the center of the facing. Had I chosen to only drill a touch hole, it would have been fine and I would not have had to do this. In fact, I would have preferred not to and in the future will probably just drill a 5/64ths touchhole and cone the outside a bit.

BUT due to the size and shape of the touch hole liner that i was using--standard 1/4 28 liner--I had to chamfer the face or the liner would have been half open half closed, and would have created not only a place for gunk to collect but potentially a place for explosive gas to redirect and potentially cause a failure in the liner....

failure being a nice way of saying, "i was afraid that it would blow the liner out of the gun"...

Basically, it just makes a straighter path, and allows the powder to drop straight into the touch hole liner chamber, especially if you use 3F powder, which I do in that particular fowler.

Cheers!