KLM;
Good morning to you sir, hopefully this still Sunday finds you well.
While this isn't exactly real world experience with a Mark V, it might be able to point you in a direction that will enable you to accurately calculate the combined parts weights of your project.
https://www.24hourcampfire.com/ubbth.../Rifle_Parts_Weights_Library#Post6692788Based upon a bit of a foggy memory this morning, I'd say that if you're starting out with a Mark V bolt with 9 lugs it's going to be a tall order to hit your goal.
I worked with a couple of the older Browning BBR actions that had a 9 lug bolt and while they were wonderfully smooth actions, the bolt itself was not that far off of a pound.
Whenever I'm attempting to build something with a specific weight target in mind, I've found one of the handiest tools is a decent kitchen scale.
I'll warn you though that light rifle projects can be a bit of a frustrating windmill to tilt at, especially so if one starts out with a beefy action/bolt combination.
Hopefully that was some use to you sir and good luck on your rifle build.
Dwayne