Centerfire conversion

[cockney rebel]

I  just acquired an original Spencer Carbine and I am looking for a centerfire upper breach block assembly.
All the ones regularly quoted seem out of production.
Has anyone tried a Chiappa 56-50 breach block in an original Spencer?

Cockney Rebel

[El Supremo]

Hello, Cockney Rebel:

Good idea, but:

I recall, but cannot find a Post by one of our SSS members about the Armisport upper center fire block working/fitting an original.
Hopefully he will see this and share more.

It might help others if you share some close, clear photo's of your carbine's serial number. 

Also, there were some variations in the "fitted" block dim's on originals and FOR SURE with repro Armisports.  A drop-in fit might be a bit of good luck.  I have seen some frustrating interchangeability situations. 

I do not recall seeing a report from the last person that was going to try the Armisport way.  My suggestion was to try to get Armisport/Chiappa's Dayton, OH parts center to allow a return if fitment was a problem.  Smiles.

Very respectfully,
El Supremo/ Kevin Tinny

[Sedalia Dave]

Thread describing an original breach block that was modified.

https://www.cascity.com/forumhall/index.php?topic=53793.msg652457#msg652457

[Sedalia Dave]

Thread stating that a Taylor's breach block did fit.

https://www.cascity.com/forumhall/index.php?topic=5982.msg69847#msg69847

[Sedalia Dave]

This info was worth reposting

<quote>
The S&S (and Buffalo Arms) blocks will drop right into most PARTS INTERCHANGEABLE Spencers. The problem is, civilian Spencer were made with rejected parts and are not really parts interchangeable. Probably 95% of M1860 carbines and rifles, and 75% or so of M-1865s will have no problem. (Burnside M-1865s are the safest from a block installation point of view.) With M-1867s and New Models all bets are off. It's probably 40% or less drop in fit. I have had to do some major modifications to get a block into the later Spencers. If your Spencer has 2 or 3 digit numbers on all the parts, it's a civilian gun.

If you are rapid firing, try rolling the gun 90 degrees as you work the lever. The empties then hit your offside shoulder. The best thing is that they never drop back into the chamber and cause a jam. This is especially useful with the Lane extractor guns.
<end quote>

https://www.cascity.com/forumhall/index.php?topic=2632.msg28857#msg28857

[cockney rebel]

I only got this Spencer a few days ago and it clearly needs a good strip down and clean, which will probably not happen until after the holidays.
The serial number is 60,000 range.  This does NOT have Burnside name.
My primary goal is to shoot bp blanks at cowboy re-enactments.  Secondary goal would be to build ammo to shoot, if it is safe to do so.

[El Supremo]

Hello, again:

Further on the import blocks:

From an Armisport importer who visited the Italian factories and assembly locations:
For some time, at least with the Armisport Spencers, when worn tooling was replaced, measurements for the new tooling were taken from the WORN items!  He saw as much as .060" of dimensional variation.  Dimensions of internal parts vary by production batches.  The Armisport/Chiappa warranty center in Dayton, OH has not been able to determine, at least for Spencer's, which dimension part ties to a production run or serial number. It's a buy and try situation. In a few cases, owners of Armisport Spencers progressed through a few, cheerfully provided replacement parts from Dayton with no cycling success.   Chambers can be all over the place and not come close to the EU approved drawing.  Ask those that line them. 

I have also encountered two Armisport 56-50 Spencer carbines, owned by a father and son, that would allow the complete block assemblies to "fit" in either, but one would not cycle ctg's if it had its original block.  Careful measuring showed no significant variations in dimensions.  The cycling problem with one was cured by swapping the complete block assembly, but it took a couple years of trying to find out why.  We discovered that the one with cycling issues had been barrel swapped at Taylors from 45 Colt to 56-50 to fill an order when no complete 56-50's were in the U. S.  When I shared this saga with the Manager at Taylors, Winchester, SHE told me "That could have happened".  To this day, the one with the swapped barrel will not cycle ctg's's with its original block, so the father borrows his son's block assembly.  The warranty aspect, which does not involve mod's that would invalidate the warranty, has been left out of this at the owner's request. Sorry to belabor.

Please be sure an Armisport upper block will be ok.  Smiles.

El Supremo/Kevin Tinny

[cockney rebel]

Serial number 60099

[Sedalia Dave]

Don't know why I didn't think of this sooner, (smacks forehead with palm) but I have both an original and a Taylor's reproduction.  Will be at least a week before I can take measurements but I'll compare the two and report on their differences.

[Sedalia Dave]

Compared an original upper breech block from my 1865 Spencer to one from my Taylor's / Armi Sport Reproduction.

Here are the dimensions that different.
Width
Original = .655"
Repro = .643"

Diameter of pin
Original = .468"
Repro = .444"

Hole for spring
Original = ..470"
Repro = .472"

Length
Original = 1.793"
Repro = 1.812"


The groove in the top of the breech blocks were different. See the below picture. Original is on the left

[Sedalia Dave]

Looking at the dimensions the two major issues is the difference in the diameters of the pin that extends into the lower breech block. This is going to allow the block tilt front to back as well as side to side.

The other issue is the breech block being ever so slightly narrower.

No idea if it will work but here is how I would approach fitting it to my rifle.

Make a shim to increase the diameter of the pin so that the block is better supported. I wouldn't make it out of brass though as it is likely to deform from the forces applied when the gun is fired. I would make it from the correct thickness of steel shim stock. I would also cut the mating edge at a diagonal so that any forces applied to the shim are not concentrated on the vertical seam.

I think you could use the reproduction spring. Again shim the hole in the lower breech block so that the spring is better supported. Only way to us e the original spring would be to enlarge the hole in the upper breech block and this would require a mill or a very good drill press with attached vice to hold the breech block securely and in the correct orientation.

Not sure if the difference in width is going to be a problem or not. Where I think there will be an issue is the interface between the hammer and the firing pin. However this is fixable as the design of the Taylor's breech block would allow for the piece that the hammer strikes to be replaced with one that was a little thicker to improve the contact area between the hammer and the firing pin. What I don't know is if you would have to add a similar shim to the other side to prevent the hammer from pushing the upper block to the left when it falls. A good machinist could add a shim to the other side to prevent this from occurring. the shim would need to be profiled to ensure blade extractor to not catch on it as the rifle was cycled.

[cockney rebel]

S&S reached back to me saying that they had some more in production so I might just go with theirs unless their price has gone up significantly.

[El Supremo]

Hello:

Please allow me add something:

In addition to the upper block's length, width, height dimensions, I have seen replacement blocks from two FINE vendors that would not fit an original Spencer rifle #2250X, without significant mod's.  The problem was the location of the guide rod in the bottom of the upper block, complicated by a slightly off-spec hole location in the lower block.

It seems that a few groupings of cartouched original Spencer's DID function as delivered, but their upper and lower blocks do not match commonly taken dim's.  Cartouched "Mass Militia" originals have presented fit issues with modern center-fire blocks. Thanks.

El Supremo/Kevin Tinny