What model Ruger #1 would be the best starting point for building a 219 Donaldson Wasp ?

Should one get a #1V in 223, rechamber it, and have a new/modified extractor put on it ?

Or if one could find a #3 in 375 Winchester, would that be a better starting place ?

Hammer

You can get whatever extractor you need from Ruger. Is the 219 Donaldson Wasp a nostalgia thing?

Yes

That should be an interesting rifle- think about putting on a Hart or other high quality barrel.A good source of information is "Twenty-two Caliber Varmint Rifles" by Charles S. LandisCopy right 1947 by Small-Arms Tecnical Publishing Co.This describes the development and loads used at this time.Try inter-library loans.
Shoot B.R. quality bullets -you just might be suprised.Ruger #1's set up properly can shoot quite well.
Glenn

Landis is a good reference. Have read and reread it a few times.

Was thinking of a Shilen benchrest-grade barrel. Benchrest barrels typically go with slow twist like 14-inch or slower. Was thinking of a 12-inch twist to ensure the 55-grainers would stabilize.

Hammer

Dear Hammer,
The Donaldson Wasp, being made from a 30-30 case will work fine with a Ruger #1/#3 standard "magnum" extractor. At least the two I made up did. I like your idea of the 1-12 as a good all-around twist. You could have an existing Ruger 223 barrel re-chambered but the accuracy "might" not be up to your expectations. Good luck on a neat project. I do quite a few #1s and #3s every year and think they make nice rifles.

Aloha, Mark

Mr. Hammer, I would make my brass out of 219 Zipper. You can drive it fast enough to stabilize 60gr. bullets with the 14" twist. I use 15 twist on 52gr. bullets. I gave Cheechako a large amount of Zipper and Donaldson brass. PM him and maybe he has some to spare. Butch