Ain’t gonna happen. … …
Look closely. Focus:-)
Sorry for the edit. I was called away.
I see Cloth outer jacket that was likely one of 2 circuit cables in volcanized cloth sheathing, Natural Rubber Insulator Jacket and AL/Aluminum conductor. Natural rubber compounds were utilized in circuit wire insulation up to at least in the early 1950’s and beyond.
Always good to note the circa the residence was erected for OEM systems and components in equipment uses. Process containing carbon-containing black rubber, vulcanize developed by Goodyear.
*Note: Natural rubber, which comes from Hevea trees, were introduced to Malaysia in the 1870s.
Tinned copper is copper with a thin layer of tin atop a copper conductor. At the termination cut the conductor would reveal copper.
Old Electrical Wiring Types, History of Electrical Wire Types
You are incorrect. You gave good links, but you did not learn from them. Perhaps you read them, but you clearly did not understand them.
While some may agree others may not.
If you believe this is tinned copper that’s your prerogative.
Not enough visible information.
The conductors in question (shown clearly in photo #5) are run inside of AC cable. Has anyone ever seen AC cable with rubber insulated, #12, aluminum conductors?
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All the aluminum conductors i have seen have been in a thermoplastic insulation. Tinned copper had the fabric braid over rubber.
In one of the posts above it states rubber was used up to the 1950s. Aluminum came into use late in the 60s and early 70s. That should rule out rubber insulation over aluminum conductors.
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I agree and Jim’s correct, aluminum NM cable in sizes #14- through #2 AWG first appeared in the 1968 NEC {336-2}. Thermoplastic insulation had already been around for many years prior to the 1968 NEC.
This is neither “ancient” nor service entry.
Aside from other’s comments, there’s a black wire on the neutral bus (top right), and a conductor with missing insulator - look at the red wire on the third breaker from top on the right side. Plenty of issues.
I commend you for taking the dead front off. You can learn a lot from these comments on your post. Many new inspectors hide behind the minimum acceptable levels on the SoP or disclaim inspecting service panels on the basis that it is dangerous. Keep at it.
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Are you referring to the bonding bushing in photo #12?
The Truth About Aluminum Wiring
People in the home building industry were looking for an alternative product that could be used safely for residential wiring and it was determined that aluminum would suffice, if it was installed correctly. Underwriters Laboratories had previously approved aluminum for interior wiring purposes as early as 1945.
Not to go off thread but, the circuit breakers appear to be designed for two conductors.
The circuits were installed improperly to the OCPD’s.
The black wire on neutrals is visible in picture # 6, top right. As for the insulator gap mentioned, I was referring to the red wire in that same picture - however, I downloaded it on my laptop to take a better look and realize it is simply electric tape; the flash reflected shining which I mistook as exposed conductor. I should have known better than to have old eyes rely on a view from my phone.
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Actually that is a bare copper conductor that is badly discolored. Similar to the discoloring on the copper bonding jumper on the bonding bushing.
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Thank you, Edwin!..I feel better now. 
…At least we are on this side of the dirt. 