Originally Posted by
Daan Kemp
Originally made in 577/450 with a Metford rifled barrel, as that was the rifling that worked best with black powder and lead bullets. After the Empire changed to 303, many Martinis were rebarreled to 303, as the only real change was the extractor and barrel. Later change over to Enfield rifling too, after experience with the new magazine LeeMetfords showed the Metford rifling, cordite, and jacketed bullets weren't compatible.
You will see the breechblock isn't 303 size, made for a larger cartridge. These are nice shooting rifles in my restricted experience.