FX Spacers distances in the Fx Crown superlight barrel

No hard & fast spec which I know of. I normally space them equally apart in the final 1/2 or 2/3 of the liner, toward the muzzle end. No need to space them back further as the liner is fixed in place at the rear.

Some folks put a ring of tape on either side of the spacers so that when the shroud is pulled off they stay in their approximate location.