Original 1858 chamber dimensions

[ian45662]

I picked up an original 1858 over the weekend and I have a few questions for those who own or shoot an original. Have you ever verified the Diam of the chamber with a slug or pin guage? Does anyone know what the specs on paper say? The chambers on this one slug in at about 451. I slugged the bore as well and of course it has odd number of grooves so a good measurement was hard to achieve but best I can tell its 456 or 457 but again I could be wrong about that maybe it is smaller. Is this normal for the chambers to be smaller that groove Diam? I am pretty sure the round ball
or conical will bump up to fill the grooves.

[Curt]

Hallo!

On originals one will get some minor deviations which is normal. I do not understand the 'why' of it other than I believe that machinery got "old' and out of spec" over time as it was used, so there was a cycle of new machines, worn and wearing machines, and new parts or new machines cycling in. Plus an issue with universal accurate measuring devices able to do "thousandths" well.

I have never seen specs or measurements for the 1858 Beals-Remington, but I assume by "1858" you are talking "hobby/collector/vendor"-speak for the Remington New Model of 1863.

One (nearly new) 1863 New Model Army measures:

1. Land-to-land: .442
2. Groove-to-groove: .459
3. Unconed chambers of .454 for all six.
4. Cylinder to barrel gap: .005

In brief, yes there was/is an expectation that the lead obdurates (expands). What typically happens is that the rear of the bullet (if standard conical) or lesser used round ball's backside, starts to accelerate from the pressure of the expanding gas pressure Before the front receives the energy and starts to move. As a result the front is "in the way" and the rear expands outwards for a brief fraction of a second filling the bore space..

Curt

[ian45662]

So even back then chambers were made smaller than groove diam. The grooves seem pretty deep. I wonder if this aids somewhat in the bullet bumping up since displaced material must go somewhere. Must have been a real chore to load some ammo since I know some was 460 and up