Chamber Insert?

[Badger]

I just saw a short video using a chamber insert, with a 45 long colt cartridge, for a Martini-Henry. Does anyone know if these are available, and where to buy one?
Thank you,
Dean (the other one)

Here's the video in "The Screening Room" ..

Martini-Henry Rifle Using .45LC (Long Colt) Chamber Insert (click here)

Regards,
Badger