5/8*24 is 0.625" diameter with 24 teeth per inch.
The AR15 crush washer is;
0.5" internal diameter
0.76" Outside diameter (uncrushed).
The AR10 crush washer is;
0.625" Internal diameter
0.8" External diameter (uncrushed)
You need the AR10 washer (the AR15 won't fit). You could look into peel washers like Gunner is recommending. I use split washers for non-timed brakes like the original A1 AR's had. Split washers let you put the muzzle device on hand-tight (only) and take them off by hand afterwards to clean the crown. Muzzle devices encourage and hide the build-up of crud on the crown, and if you're OCD like me it irks you.
The AR15 crush washer is;
0.5" internal diameter
0.76" Outside diameter (uncrushed).
The AR10 crush washer is;
0.625" Internal diameter
0.8" External diameter (uncrushed)
You need the AR10 washer (the AR15 won't fit). You could look into peel washers like Gunner is recommending. I use split washers for non-timed brakes like the original A1 AR's had. Split washers let you put the muzzle device on hand-tight (only) and take them off by hand afterwards to clean the crown. Muzzle devices encourage and hide the build-up of crud on the crown, and if you're OCD like me it irks you.