Just acquired my first Encore, a 45-70 with a muzzle brake. I have never cared for brakes, so I took it off. I was planning to install a thread protector but found that the thread on the barrel is 5/8 X 18....

Have checked most everywhere with no luck. They all are 5/8 X 24.

Any ideas where I might find one before I just whack the barrel off and re-crown it?