Recent chamber casting problems AND chamber lengths.

[El Supremo]

Hello:

Lately, several Spencer shooters have been making chamber castings to optimize various details.  We use the Brownells "Cerrosafe" alloy and achieve decent castings.

In addition to the detailed instructions provided by Brownells, we have learned:

As it should, for diagnostic purposes, CERROSAFE will flow into quite narrow, paper-thin spaces.

The Model 1860 large blade extractor cut must be well packed with a semi-flexible FILLER such as a leather strip or plumbers cast iron pipe "caulking" to prevent CERROSAFE from reaching it and creating a FIRMLY sticking remnant. 

We pour only to within .250" or so of the chamber rim cut so metal does not overflow into the extractor cut or the PARTING LINE between the barrel and receiver. 

If metal reaches these spots we have removed it by heating a metal probe and placing it against the stuck portion to soften it for removal with a dental pick. 

Like most seemingly simple things, the "you just gotta's" can bite you. 

The most significant thing we learned from the castings in ORIGINAL Model 1860 56-56's and later models in 56-50 is the chamber is much longer and ends with a gentle, almost quarter-inch long TAPER into the rifling.  Standard length, LONGER, 56-50 cases to TTL's of as much as 1.3", and longer loaded 56-50 rounds will cycle, chamber and extract from 56-56 chambers. 

Most modern Spencer reproductions and some lined bores have chambers of the same, extended length, but can have a DISTINCT shoulder and no taper vs the longer gradual shoulderless taper.

The ORIGINAL chamber "gap" BEFORE the taper, beyond both a 56-56 and slightly longer 56-50 cases can be .100", which is a relatively long jump for the bullet into the rifling.  It's sorta like shooting a 22 Short in a Long Rifle chamber. My guess, absent any research references, is the longer gap was for military practicality.

For casual and out to 100 yards shooting, widely recommended case and round lengths are fine.  If wish to tweak accuracy, try a longer case with its bullet seated to reduce the jump. 

The Accurate Bullet Molds' #'s 51-320S and 51-350S work well in most twists, but at around 1,100fps muzzle velocity, in 36" twists, are suitably accurate and quite stable to 300 yards.

All the best. Smiles.
El Supremo/Kevin Tinny

[Arizona Trooper]

For Spencer chamber casts I like sulfur. Melts at about the same temp as cerosafe and if it gets someplace it shouldn't you can easily break up the casting to get it out. Theoretically it's not as dimensionally accurate as cerosafe, but the difference is minuscule.

[El Supremo]

Great info and thanks, Arizona Trooper:

If possible, Tony, please attach photo's of a sulfur one.  Smiles.
El Supremo/Kevin Tinny

[Arizona Trooper]

Bobby Hoyt has them, or did. I made those about 10 years ago for him.