Seneca Patent Breech

[Eddie Southgate]

Does anyone make a replacement Patent Breech Plug for the Thompson Center Seneca ? I want to make up a drop in with a .45 Douglas barrel and do not want to have to swap out the plug every time I want to change calibers . Thanks.

Eddie

 

[Zonie]

Give Track of the Wolf a look in this link:

https://www.trackofthewolf.com/List/Item.aspx/667/1

There should be something there to fit your needs.

 

[ohio ramrod]

I got a breach plug for a Cherokee from Track of the Wolf , So give them a try .They might have one for the Seneca. :idunno:

 

[bob308]

fort chambers in Chambersburg pa. has a bunch of breach plugs. they do mail order.

 

[Eddie Southgate]

Thanks folks. Track Of The Wolf is out currently so I asked to get a notice if they restocked .

Eddie

 

[Richard Brinkman]

Something to watch for is that some of the TC breech plugs are a odd ball thread and the Douglas will be a standard thread?

 

[Eddie Southgate]

Something to watch for is that some of the TC breech plugs are a odd ball thread and the Douglas will be a standard thread?

Not a problem , got an Uncle that owns a machine shop.

Eddie

 

[ohio ramrod]

machine shops are nice! I retired from job in the tool room on the midnight shift. It was so nice to have all that equipment available. Now that I am retired I "just" have my two Bridgeports and an old engine lathe. :idunno: :idunno:

 

[Scota4570]

I am also working on the same project. The guy who makes the repro plugs for Track is moving his shop and no plugs are available.

If someone has one I was like to buy it.

The original plugs were 11/16 x 20TPI. That leaves only 0.060" of barrel wall remaining. 0.060" is the thickness of a writing tablet cardboard backer. This is unsafe IMHO. The Track repro plugs are 5/8 x 18TPI. That is much better. The original plug has a 0.36" powder chamber. If you re-thread it to 5/8x18TPI then the plug itself has a thin wall and IMHO is now unsafe.

Many will argue that the Cherokees and Seneca's are perfectly safe. Mine had a gap between the barrel face and the plug. That gives a greater area for the gasses to act upon. Coupled with the over torqueing TC was famous for and a little corrosion and I have no confidence.

That is me, and maybe I worry too much? The cost of it failing could somebody being killed or maimed, so I choose to be a worrier.

 

[bob308]

you may be right about the threads. but the gap between the back of the barrel and face of the breach plugs. is not a problem. just run it up with a piece of soft brass. then work it down so it looks like an inlay.

 

[Scota4570]

Interior gap, between the interior shoulder and the snout of the breech plug. Not on the outside where you can see it. Outside is tight. TC used a smash fit to make the top flat align. They did not care about what was inside. To do it right both must fit 100% contact at the same time.

 

[bob308]

I can see you don't understand about fitting. yes the in side is important. it is the threads that take the pressure. if they let go the breach plug out side fit will mean nothing. the way I said to do it you will end up with what looks like a wire inlay around the out side of the barrel.

 

[Rifleman1776]

Many will argue that the Cherokees and Seneca's are perfectly safe. Mine had a gap between the barrel face and the plug. That gives a greater area for the gasses to act upon.

That was a common condition with many/most early TC products. It was something that John Baird of the now, long defunct, magazine Buckskin Report railed against. True, an unsafe condition that can be repaired only shortenting or replacing the barrel.

 

[Scota4570]

Communication in writing is tough. You're jumping to conclusion about my skills and depth of knowledge is way off base.

The end of any breech plug must form a tight, leak-proof fit against the interior shoulder of the barrel. This is a safety issue.

TC did not understand this and did it wrong on many rifles. The gap caused fouling to rot the threads. Pyrodex made it worse. They did not fit anything; they forced the barrel to line oup with a flat by brute force, and only on the outside shoulder. This sometimes overstressed the barrel and threads. Add some corrosion and it could cause the strength to be compromised of the whole assembly.

The fit of a patent breech on the outside shoulder is an aesthetic issue. One certainly could avoid the task of properly fitting the plug by using a copper washer on the outside. It is a mickley mouse way out of doing it right.

To do the job properly both shoulders should mate up at the same time, with 100% contact.

 

[Eddie Southgate]

Communication in writing is tough. You're jumping to conclusion about my skills and depth of knowledge is way off base.

The end of any breech plug must form a tight, leak-proof fit against the interior shoulder of the barrel. This is a safety issue.

TC did not understand this and did it wrong on many rifles. The gap caused fouling to rot the threads. Pyrodex made it worse. They did not fit anything; they forced the barrel to line oup with a flat by brute force, and only on the outside shoulder. This sometimes overstressed the barrel and threads. Add some corrosion and it could cause the strength to be compromised of the whole assembly.

The fit of a patent breech on the outside shoulder is an aesthetic issue. One certainly could avoid the task of properly fitting the plug by using a copper washer on the outside. It is a mickley mouse way out of doing it right.

To do the job properly both shoulders should mate up at the same time, with 100% contact.

So to fix this you turn the rear of the barrel off enough to let the plug snug up against the inner shoulder and line up on the top flat . Correct ?

Eddie

 

[Grenadier1758]

In theory you are correct. In practice its not that simple. There are three surfaces that have to all align at the same time. If you remove enough barrel material for the shoulder and the breech face to align, then the top flat is often to one side or the other. Installing a breech plug especially a patent preach can be very time consuming. Often the bore of a barrel is slightly off center at the breech so the top flat is identifiable and only one flat can be considered the top flat.

Once the top flat is identified, the length of the threads to the end of the barrel can be measured. That measurement has to be made in accordance to where the threads are cut in the barrel and on the breech plug. It take a lot of fitting to get it all correct.

 

[shdwlkr]

So if Thompson Center got this fact so wrong are you saying that tc black powder firearms are just waiting to let go and harm the user, those close by because they didn't attach the breech plug correctly?
Seems that would leave Smith and Wesson the current owners of TC products in a bit of a bind as the only way out for them is to say they didn't actually make them, but we all know that courts don't always let that argument stand.

I wonder how many tc firearms have been fired how many millions of times and we have never heard of this very dangerous issue being mentioned.

 

[bob308]

and so how many barrels have you made and breached?

 

[Scota4570]

A bunch......

 

[Scota4570]

A bunch......

Breeched a bunch, I am not a barrel maker. It is irrelvent though. It seems like this is getting to be about my qualifications.

Here are instructions that tell it how it is:
https://www.trackofthewolf.com/Categories/PartDetail.aspx/1012/1/LABOR-BP