M1861 v. M1863 lock plate

[RSMorris]

Is there any way to tell the difference between a M1861 from a M1863 lock plate without seeing the date, lock make, or hammer?

 

[JOHN42768]

Springfield !863 finish was case hardened vs 1861 metallic brushed I believe

 

[RSMorris]

Springfield !863 finish was case hardened vs 1861 metallic brushed I believe

Thank you, would case hardening have been a requirement for the contractors also?