Thompson center inter changability

[Gcs71]

Exactly how are the “flats” measured?

 

[deerstalkert]

Exactly how are the “flats” measured?

take your calipers and slide the jaws down on each side of the barrel. that is across the flats.

 

[necchi]

Exactly how are the “flats” measured?

"Flat's" refer to octagon barrel. The measurement is from one opposing side to the other, as exterior.
When dissected with a micrometer the differences will be noted in or near 0.0625 of variations of 1" vs 15/16".
Anomalies of manufacture within a few thousands are common,, but a 1/16" is commonly measurable..
Ask your local Cabinet maker or finish carpenter.
In my experience, when a comparable barrel is found to fit the stocks channel,,
The major issues are the tang/hook fitment of the existing components and proper tension of the lug key.
Folks have been swapping out the T/C parts for years,, and that's the trouble and/or challenge.

 

[Gcs71]

another question is, what does it take to remove a breech plug? Is just simple standard threading rules? or Are these best left alone?

 

[longcruise]

Removing a tc breech plug is best done with a special tool. Actually, there is one for sale in the classifieds.

It also takes a wrench to slide over the tool. I had one removed and reinstalled by a Smith and it was quite a tight fit. We went to his machine shop and he placed the barrel in a vice and slid the tool on. Then he adjusted a huge crescent wrench to the tool and literally bounced on it with his full weight to get it started!!

This wasn't unusual. TC installed all of their breech plugs with lots of torque.

My advice is to avoid doing it unless absolutely necessary!

 

[Bad Karma]

You’ll need a stout bench vice. 4” harbor freight vices need not apply. I spent the 50 bucks for the Rice Barrel company vice jaws, then the TC breech plug wrench. I used my corp stop flat jawed wrench to grab the breech plug wrench and hauled away on it. Proper tools make it easy but yes, TC used a lot more torque than necessary.

 

[PioneerValleyOG]

Those older TC 56 smoothies shoot better than they are supposed to!

I had one back in the early 80's in Mass (before I escaped to Maine!) when a smoothie was needed for the BP season, and with careful load development (the details are long forgotten -- so don't ask!) I was getting an honest 2" group at 75 yards, which was plenty for the woods I was hunting.

Old No7

This fine piece is an absolute marvel at 50 yds with patch and ball. Also able to dump birds, squirrels and small game if loaded with 2/3 #6 shot as it's a smooth bore. My open sights are lollipoped. Crazy accurate.

 

[nkbj]

I'm sitting down this evening to decide the fate of a lefthand neglected 3rd hand .50 bore New Englander barrel; what I'd prefer to have it capable of, what I'd like to be able to do with it. So I listed out hunting for small game, large game, off hand target shooting, bench shooting, this and that. There's just no beating a "smooth rifle" for all around game shooting. If I was after another hunting piece then by golly this barrel would get bored out as large as feasible for the depths of the dovetails and screw holes.