Proof Tests of Spencer's

[Harve Curry]

 
How did Mr. Spencer proof test his firearms ,and did he publish the results?
Did the military proof test the Spencer carbine or rifle?

[Nlneff]

I have a couple of references to proofing the Spencer in Marcott's Spencer Repeating Firearms.  On page 42 there is a letter from JNO  S Chauncy stating that each barrel was proofed 2 times, once with a 280 grain powder charge and cylindrical ball, and once with a 250 grain charge.  Of the 700 barrels proofed, one burst.  This may refer to the barrel being tested before assembly.

On page 106, during the Hancock trials, during tests for "Strength of construction" the carbine was fired with a 400 grain bullet and 65 grains of powder (presumably a special cartridge too long to function through the magazine.) and with 70 and finally 75 grains of powder.  The cases burst and could be removed with difficulty and the extractor was damaged.

Seems a poor way of proofing to me, as likely to cause damage as weed out a weaker barrel.

[Fox Creek Kid]

Seems a poor way of proofing to me, as likely to cause damage as weed out a weaker barrel.

Be that as it may, every country in Europe does this very thing today with all firearms.

[Harve Curry]

Does anyone know if/how Burnside, Romano, ArmiSport or any others makers proof test there copies?

[French Jack]

The Italian ones by Armi Sport are proved by the government proof house.  Very likely each major component is proven, then  a final definitive proof when the arm is assembled.  American arms have never been required to be proven by any government proof house, what proof is done, is conducted by the manufacturers.  Not all arms were reliable, even with the lower pressures of black powder, for example the majority of the Walker Colt's burst the cylinders.  Not that many were made, and their tendency to self destruct when loaded to capacity sent most of the issue received by the Texas Rangers to the scrap heap.

[Harve Curry]

The Italian ones by Armi Sport are proved by the government proof house.  Very likely each major component is proven, then  a final definitive proof when the arm is assembled.

It would be interesting to read the details of that.

[Two Flints]

Hi Harve,

I just received a reply from Armi Sport regarding their proofing data  for their Spencers.  I'm not sure this is the information you were looking for, so please let me know.  This was the information I received:

"Hello Two Flints,

Here is the data you requested, I apologise again for the delay in getting back to you with this information, we're getting ready for the Shot Show...

56/50 average shooting pressure 2050 bar
56/50 shooting pressure during proof house testing 2665bar

bore dia     12.7mm- .500"
groove dia    12.95mm-.509"
groove depth    0.125mm-.0049"
grooves            6
twist   1 in 508mm- 20"

If you need any additional information, please let me know."

[Harve Curry]

Thanks Two Flints.
I looked up the metric/bar to psi conversion ( here's the link to look it up;  http://www.ilpi.com/msds/ref/pressureunits.html ) :

2050 bar =          29,732.7134225 PSI , or for our purposes 29,700 PSI average shooting pressure.

2665 bar =          38,652.5274493 PSI , or for our purposes 38,600 PSI shooting pressure during proof house testing.

The 29,700 PSI average shooting pressure puts the Armisport Spencer 56-50 copy in it's own strength category 

[Two Flints]

Harve,

Thanks for the conversions. Any comment on the information that Armi Sport provided?

Two Flints

[French Jack]

Before anyone starts out with a load that pushes the envelope, remember that 38K PSI is a lower pressure than either the Remington Rolling Block or a Krag-Jorgensen was able to handle.  It is pushing the envelope for a pistol cartridge, as both the .357 Mag and the .44 Mag are loaded to approximately the same working pressure as the PROOF pressure, not the working pressure.
What it boils down to is to use caution and common sense in loading smokeless powders.  So far not a lot of information is out there that is supported by pressure testing and research.  If enough demand and interest is generated, that may very well change.

Just my thoughts.  Enjoy.

[Black River Smith]

Groove diameter is really 0.509", according to manufacturer.

I have been sizing 0.512".   Dixie GunWorks list 0.512".  Most discussion was around 0.512"

I thought that was the correct info.  Never bothered to slug, trusted the available info.

May have to get different sizer or different bullet.

Thanks for obtaining the info Two Flints

[Fox Creek Kid]

Why size at all if they will chamber?  I simply pan lube and load. Mine slugs 0.512 by the way and my bullets run about 0.513.

[French Jack]

My Armi Sport slugs out .512"+, I use bullets either .512 or .515 as cast, as the chamber on mine is cut a bit generous in the throat.

[Harve Curry]

Great Ceaser's Ghost   With the wide discrepancy of bore/groove diameters over the manufacturers claim, how can we be sure of their proof load spec's

[matt45]

Hello the Camp,
This is why this is a great forum- I've been looking for someone to convert the metric stuff (I'm mathematically challenged)
Some time ago I sent Two Flints some data that Starline sent me, it had the European equivilant of the SAAMI specs- that, if converted, would give a good operable idea of limits.
As far as groove diameter goes, if using lead bullets, .003 is nothing to worry about, vis a vis pressure.