The Model 742 is a newer improved version of the Model 740.
The following is a quote from Eugene Myszkowski's book Remington Autoloading & Pump-Action Rifles A History of the centerfire Models 760, 740, 742. 7400 & 7600. The discussion is about the Model 740 carries over to the Model 742.
"L. Ray Crittendon, in 1951, developed the Model 740 magazine bolt release that generated much discussion. Testers liked that the magazine held the bolt open after the last round, but almost universally condemned the need to release the bolt in order to drop the empty magazine. Some preferred to use the Model 760 magazine, which allowed the bolt to close after the last shot. Remington's autoloader safety principle, used over the previous 40 years, won the day -to see the rifle open and empty after the last shot was fired."
