You can request a owner's manual at the Remigton web site.
I'd get in touch with Remington. They can tell you. I would expect that it's possible, as they should be pretty interchangeable, however, it would be unlikely.
The model 721 was produced from 1948 to 1962
Actuate the bolt to the rear and there is a tang in front of the trigger that hangs down..Press up on this tang and pull the bolt back and it will remove it from the action.
To disassemble the bolt on a Remington Model 721 rifle, first ensure the rifle is unloaded and the safety is engaged. Then, remove the bolt from the receiver by pulling the bolt handle fully to the rear and pressing the bolt release located on the right side of the receiver. Once the bolt is out, you can disassemble it further by unscrewing the firing pin assembly from the rear of the bolt body, allowing for access to the firing pin and spring. Always refer to the manufacturer's instructions or a gunsmith for specific guidance and safety precautions.
The Remington Model 721 in .300 H&H was manufactured in 1948 with a 24" or 26" barrel.
100-400 or so
100-300 USD depending on condition.
If it is in 100% new condition and unfired, it could be worth around $700.00.
100-300 USD
1 in 10
General information on the 721 can be found on the Remington website here: http://www.remington.com/library/history/firearm_models/centerfire/model_721.asp
Your Remington model 721 was produced from 1948-1962. If you can supply the 2,or 3 letter code on the barrel we can pinpoint the month and year of production.