Ingersoll St Paul (The Other Ingersoll). What Is This Filler?

[Greenie]

This is an Ingersoll St. Paul, which is related to Redipoint and not the tack twist type of Ingersoll from Newark.

 

Here is a great history of this company.

https://www.fountainpennetwork.com/forum/topic/13629-a-chas-ingersoll-ebay-find/?&p=1584148&hl=redipoint&fromsearch=1&do=findComment&comment=1584148

 

BUT WHAT IS I​T?????? I bought it as you see it. No real trace of sac (maybe a tiny piece in the mystery piece). The barrel is an almost plain tube. There is a blind cap. And this odd thing inside. I can't be certain if it is even a correct piece. The pen is marked patent pending, so I can't easily look at the patent.

 

Does that metal piece grab the end of a sac and then you use it as a twist filler? There is enough room under the blind cap for the piece to stick out, and the rough surface seems to be made specifically to grip with your fingers. The section does not have a hole for a breather tube, so I doubt you pump it. I says self filler, the section is made to take a sac.

 

 

 

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[Greenie]

In lieu of any educated guesses, I have decided that this is how the parts work. I welcome any other ideas!