Jim,
I was hurrying and wasn't as precise as I should have been.
But, precision would have required a LOT more time than what I had at that moment. The early cartridge era was a time of HUGE innovation, experimentation, and adaption in the cartridge manufacturing industry.
I've seen some experimental (and some limited production) cartridges that would blow your mind, and which really defy all neat classification.
There were one piece folded balloon head cases, multi-piece balloon head and balloon head folded cases, there were folded solid head cases, there were multipiece folded heads that, because of the construction, technically have a "solid" rim....
It's a real mess.
Here's an illustration that shows some of the more common (but by no means all) of the different type of early cartridge cases.
http://www.frfrogspad.com/miscellf.htm
"First, none of the bullets of those different .45 caliber cartridges seemed to have a flat point, which I had thought was a characteristic of the .45 Colt, as well as most of the other contemporary Colt branded cartridges."
Flat point was the most common, but it wasn't the only type loaded. I've seen vintage round nose .45 LC, as well.
"What is inside primed?"
To expand on Jim's explanation, inside priming was an intermediate step between rimfire and true centerfire primarily resulting from the use of drawn copper cases.
Cartridge is strong enough for a cartridge, but there were a lot of problems in getting a copper case to hold a berdan or a boxer style primer. The copper simply isn't sufficiently robust.
The alternate solution (until deep cup brass drawing technology caught up to the point where brass cases were viable) was inside centerfire priming.
These are two examples of Benet inside primed rounds from my personal collection:
The one on the left is a .45 S&W, the one on the right is a .45-70. Both were most likely loaded at the Frankford Arsenal in the middle to late 1870s to early 1880s.
Copper cases and Benet priming was largely a think of the past by the middle 1880s, being replaced with what we recognize today.