the original TESCO shotgun cartridge is a paper cartridge with "Schlußspiegel". the german Spiegel means not mirror but sabot like in "Treibspiegel" and is a lightly conical massive end piece. this conical end was pressed into the conical chamber for obturation.
the primer have a steel pin inside driven into the needle fire pill by a common firing pin. so its a missing link between the needle fire and the center fire cartridge. to give the thin paper cartridge more strength it have a second high base most time black lacquered steel.

this illustration from 1873 show the cartridge that was developt in the 1860s

beside of Dreyse was Teschner Collath the only firm with a complete proprietary shotgun cartridge family. this happen in the 1860s when the muzzle loader gun was still predominant and the pin fire cartridge was brand new.
TESCO named the caliber by numbers where No. 0 was the biggest( close to 10 ga) and No. 8 was the smallest( 28 bore)
please dont ask where No. 2 is, nobody knows

most common is No.1 , 3 and 4 what is more or less 12 ga, 14 ga and 16 ga
no surprise! you will find for every Collath cartridge a CF shotgun shell that will fit into the chamber.

the Collath gun will fire common center fire primer without problems and Tesco start probably in the 1890s to make the TESCO shotgun cartridge with this primer also.

"Für das Ausland..."
- "for foreign countrys where its maybe a problem to get our own shotgun cartridges we make our guns fore the common center fire cartridges on special order"

the "Diana" cartridge wit another base but the TESCO primer

Teschner Collath 12 and 16 ga paper shells

this shotgun cartridges are rare on the collector market today! I found only 4 paper shells in my box.
from left to right:
12ga. Gevelot pin fire, old Schönebeck 12ga BP, new 12 ga Gamebore BP, old style Tesco No 1 BP shell with Gevelot primer( up to the 1990s the most used center fire primer in europe), a No 3 BP shell with Tesco primer, a No.4 Nitro shell for a center fire primer similar to the moder 209 shotgun primer and No. 4 Nitro shell without the second black steel base for gevelot primer

why BP and Nitro shell? for some time it was popular to distinguish BP and Nitro shotshells by green and red paper. something that survive in the little RWS "Alarmpatrone" blank cartridge loaded with green paper shells for black powder up to now.

my gun is a No.1

a 12 magtech and a 12 ga. Schönebeck shell fired in the gun

magtech brass have a thin rim and the primer try to leave the pocket

12/70mm long shell, 12 ga Magtech brass( only 63mm long) and the 12 ga Schönebeck cut down to 65 mm

70mm long shell in the right barrel and 65 mm long in the left barrel

when looking into old stock I found 400 unfired but primed( Gevelot primer) 70mm long Schönebeck shells. they may be over 20 years old now because the 209 primer came then in common use. cut the shells on a buzzsaw what need a little bit over 30 minutes for this 400 pieces. you need the sharpest saw blade you can get for this work. there were also 400 -500 76mm or 3" long unfired paper shells I forgot

but they were store away for the things to come.