The muzzle thread protector is off the shelf, $12 from Grovtec:

https://grovtec.com/products/thread-protectors?variant=39549522772039

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It is a handy size: terminal 5/8" of barrel is threaded 5/8"-24 tpi and OD is 0.750",
a scant bit larger than the 0.720" barrel diameter where the threading ends.
The Super Grade muzzle diameter on the M70 24-incher is 0.730".
No. 5 sporter is a happy contour for a .458 whether from McGowen, Douglas, Pac-Nor, or Shilen,
all pretty close to the Winchester contour.

Ron aka "Rip" for Riflecrank Internationale Permanente
NRA Life Benefactor and Beneficiary
.458 Winchester Magnum, Magnanimous in Victory
THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.