To the best of my knowledge, the 24" bolt actions were all made in 1964, the final year of production. Since most of the models 10, 11 and 12 were made for about 3 years, you can extrapolate somewhat and guess that about 1/3 of production was with the 24" barrels. These were apparently the same barrels used on the wood-stocked Remington .22s in the same configuration. You can also approximate the number of smoothbore Model 10s made in the same way - about 1/3 of the total number. Here's my chart on numbers produced of each Nylon variety:
