Spencer barrel dimensions

[trenches]

I'm working on making the Spencer barrel and I need some dimensions. Like the muzzle diameter of the 56-50 version. And what kind of taper does the barrel have. Straight or what?
Oh, and the length of the forend.
I hope to get the barrel chambered, threaded, fitted to the receiver in the next week or so.  I'm going to use a version of the Lane extractor as the rim of the .50-50 is smaller than the 56-50. Not going to use the blade extractor either.

[El Supremo]

Hello:
For consideration:
There is a taper and there are flat spots at 3:00 and 9:00 ahead of the chamber section.
The barrel threads in your receiver should be square.
Nominal muzzle OD varies, but .800"/.805 " at muzzle and 1.080" at the receiver are averages on my bunch.  Forend length measured in the barrel channel is 9 3/8".

I suggest you wait for more dimensions from those that have seen more originals than I.

Please share your progress and photo's.  Tx.
El Supremo/Kevin Tinny

[trenches]

thanks. those are what I need. I knew there was flat spot on either side. It barely shows up in pictures.
ever try to work on a 27" barrel with a 4" lathe bed. Because the spindle hole is around 3/4" I couldn't run the barrel through the spindle.
I have a SB405 lathe that was given tome by a friend. works great but does have some limitations. that being one of them. So I had to turn down the muzzle end to 3/4" so I could get enough of the barrel in the spindle so I could chamber it. With the reamer in a floating reamer holder and in the chuck in the tailstock they take up a bit of room. But I gained enough to ream the chamber.
Hopefully I'll get the chamber done this week. Then the threads will get done as will the rest of the barrel work.

[El Supremo]

Hello, Trenches:

I recall a post here years back that there have been different barrel threads used by the factory, possibly to prevent barrel swapping between military and sporting rifles.
So be sure of yours, please. 

Regards,
El Supremo/Kevin Tinny

[trenches]

I just turned square threads on a piece of AL round stock. Went ok. but 170 year old threads don't quite match up to new ones. But the test barrel went in ok. No slop. Nice and tight. Next step is the real barrel which is already chambered.
I always do a test with a piece of aluminum. That way nothing important is ruined. As you can see, the thread length is shorter. Instead of the 1" I needed for the smooth smaller shank I only turned it to 3/4" long. Oops.
But now I have the guide to do the real barrel. And the correct measurements.
BTW, I used a .500 S&W Mag chamber reamer. Only ran it into the depth of the length of the trimmed case. Then made the rim cut with a boring bar.

[El Supremo]

Hello, Trenches:

Thanks for the photo's and helpful details.
Please keep them coming. 
I think your square threads effort is a first, here.
All the best,
El Supremo/Kevin Tinny

[trenches]

Well, the barrel is 90% done. It's chambered, threaded, and installed. It locked up nice and tight and right on the money. Stuck the breech block in and no slop at all.
Cutting the threads turned out to be a piece of cake. I practiced on a piece of AL round stock. Saw what I had to do.
Because with a 10tpi change gear in the lathe I did the threads by hand. The carriage moves very fast and I didn't want to crash into the shoulder of the barrel.
So I moved the chuck by hand while keeping the half nuts engaged. Went to the end, returned the tool bit to a bit past zero, then reset. Took .001" off at each pass until I got to .035' deep.
Next step is cutting the slot in the bottom for the extractor/ejector and machining the flats on the side of the barrel. And of course trimming the barrel to 22", crowning it,  and then tapering it. I'll do the dovetails later. It's easier to get the sights lined up when the barrel is in the receiver.
So, the real critical work is done.

[trenches]

The Spencer as it is now.
BTW, I installed the innards. Found out that the screw that connects the lever to the breech block is 4-48. Strange to find that on an Italian made part. That part is back ordered so I made a temp one.
The action opens and closes without binding. Nice and slick. Locks up nice with a dummy round in the chamber. And when fully open it stays there. It doesn't come out. Right now I have a temp spring in the breech block.
The lock is the one I bought from Taylors. Very nicely made. And it fits.
Right now the rifle is a combination of new and original parts. And ones I will make.