Other than the stocks, barrel crowns, and scopes used what are the major differences between these two rifles in terms of how the Marine gunsmiths upgraded/finished them?
The M40A1 was built by Marines using old M40's as a base. The M40's were built by Remington and were not much different from a stock Remington 700 varmint special. If you read through both " build guides here on the hide you will quickly see the differences.