I have the pic only in this size but you can safe it and make it bigger. the cartridges are the 20/50 bullet cartridge, the 12,7x44R and the 9,3x57R/360BPE. the modell 17a was made in 28/50, 24/50 and 20/50, the modell 17 b was made with 12,7x44R which is allways the center fire version because the rimfire cartridge is a 12,7x42 iirc and the modell 17c was made with a 9,3x57R barrel.
I do not belief that daryls gun is a modell 17 because they allways have a pistol grip but cant say it not which model it realy is. I think that this gun deserve a good rework.

like to see a chamber cast