Raimey,
Did the owner of this rifle have a chamber cast made or did he take the word of the person that sold it to him, who may have just tried cartridges until he found one that "went into the chamber". The 444 Marlin can easily be confused for the 11.15x60R LK Express.
The 444 case has about the same head diameter as the 11.15x60R, the rim diameter is a little less than the 11.15, since it is a simi-rimmed case. The 444 case is about 57mm long, which is only around 3mm shorter than the 11.15. A 444 cartridge would likely easily but closely fit into an 11.15x60R LK Express chamber. ( see Dixon p.66)
Mike

Last edited by Der Ami; 05/30/23 09:39 AM.