From "The Ross Rifle Story" regarding the MkI Carbine:
"This is the first Ross rifle issued to the RNWMP and was abandoned when it could be done with the least political repercussions. Weak springs, cast shoe (receiver), tight bore of 0.300", fragile rear sight, and no primary extraction for spent rounds were among the chief complaints against this rifle."
We must assume, however that the MkI Carbine was suitable for our military.