Spencer 1860 and 1865 receiver dimensions?

[El Supremo]

Hello:

I may have touched on this before, but need more input to be EXTRA-SURE about the MAXIMUM THICKNESS and TOP-TO-BOTTOM dimensions just behind the front of receivers of ORIGINAL 56-56 and 56-50 Spencers and Burnside Spencers. Please measure THICKNESS sufficiently behind any radius on the leading edge.

Marcot is silent on this topic. 

Am not intereeted in the "smaller" receivers used for smaller cartridges than 56-56 and 56-50.

So would those that can, please measure yours and post here what they measure along with MODEL, rifle vs. carbine and name on receiver with an APPROX. frame number.  If you would rather PM, fine.

I hope to resolve IF SOME original 56-56 and 56-50 models had thinner side walls and maybe less frame "height".  A few thousandths are not significant, but a 16th or more will be. 

I have measured a few 1860's and found them remarkably consistent to within .003", but people keep insisting to me that 1865 receivers were thinner/slightly smaller.

Any help will be most appreciated and included in a SORI Thread early next year.

Helpful Spencer SPORTER receiver thickness info. is in Matt Sears', "Spencer Sporting Rifles", page 103/66, figures 58 & 59, showing thinner receivers, but apparently normal thickness blocks.

Happy Holidays,
El Supremo/Kevin Tinny