I know Savage used 1/4x28 TPI on some.
I had to go thru the same process with a Choate/Savage combo a couple of years back.
Unless Savage has changed things (which I doubt), 1/4 - 28 is the correct diameter/pitch; just buy a couple that are definitely longer than you need and cut them down until you get the right amount of thread engagement into the action.
The front one was time-consuming to get to the right length; it was a matter of cutting, fitting/assembling, measuring, and repeating until I got the tip of the bolt just below the surface when fully tightened - there's not a ton of receiver metal to work with there.
I don't think that my final products would have been whole-number lengths or regular fractions thereof; they were probably some random-looking size like 7.89". Note that the length will also be affected by washer thickness under the bolt-head. (You'll want to chamfer the end of the bolt after it's been cut off.)
I used FastenerForce here in Victoria, as 1/4 - 28 is not a threading you'll find at Home Hardware/Can Tire/Home Hardware, especially if you want stainless or nitride. Not sure if FastenerForce is in Ottawa, but something similar will be.
To save gas, maybe buy a few extras while you're there, just in case you decide you took off a bit too much with the last cut...
Go slowly, and good luck!
