.303 M-10s?

[Surpmil]

I'm thinking you probably mean was the M10 .280 sporting rifle ever made in .303 in the same general configuration and with a similar level of finish?

The answer is basically yes, that rifle was called the E10 or 1910-E depending on the sources. (Photos attached)

The base model sporter in .303 on the 1910 action was the R10 or 1910-R.

The same stratification was offered in the sporters previously built on the MkII or 1905 action.

The 1910-E was also built in .35 Whelen, but in very limited numbers.