5, 7, 9mm Pinfires and inside primed Centerfires

I’m not in the know when it comes to pinfires or those inside primed centerfire revolver rounds, so this might be a silly question.

Are those CF rounds an “upgrade” to the older pinfire rounds? Are the bullet, mouth, and head diameters compatible with each other. I guess at those days there were great tolerances even on the same ammunition.
Were (some) of the earlier pinfire revolvers converted to the then-new inside primed centerfire revolver rounds? Thinking about the 5, 7, 9mm here (and maybe the 12 or even 15mm ones - not sure if the were ever produced as inside primed centerfire).
Tried to search here and google, but no success.

In a way they were an upgrade, as a better perhaps more reliable waterproofing system. Some of the inside primed were better than others. A few arms were converted (mostly by governments for the police/military) but not a lot (relatively). A gun maker would rather sell a new gun than spend time converting an old one.

Conversion was a big deal the cylinder slot(s) where the pin went had to be safely filled or a new cylinder made & the hammer to strike through the recoil shield as opposed to over it.

As far as I know, some of the early cartridges for converted pinfires had rims that were noticeably thicker than “normal” cartridges.

That was a solution to the problem of the pin slot in the cylinder wall. The chamber was counterbored beyond the pin slot to fit the thick rimmed cartridge.

Thank you for your reply. So were these new CF cartridges built for the size of the pinfire revolver’s chamber (diameter) and bore size? So if you wanted to shoot the fancy new centerfires, only a “little” modification was needed on the pinfire revolver?
Or am I tottaly wrong here, and the new 5, 7, and 9mm CF cartridges were designed from scratch, and they just bare the same NOMINAL dimensions in their name… maybe people were familiar with those numbers and could know what to expect.

I would not use little as a term to describe the firearm modification.

The new CF cartridges were designed from scratch for Walking Sticks, new revolvers / pistols and to invent a better cartridge than the Pinfire.

That they might have some of the same measurements, may only have been because it was a tool / die on hand that could be used in the new design.

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The 9mm Perrin is an example of the type of cartridge I mentioned. As far as I knew, these were designed for pinfire conversions.

Some photos here:


Falcon, where have you seen that about perrin ctges !!!


I thought I had read it on here years ago. I will edit the posts if it is not correct.