My manual gives 5.5 to 8.0 of Unique for 158 grain bullets. So 5.8 will be safe, but use the dipper to get close to the load you want then use a powder trickler to finish. The dippers can vary +/- a whole grain. And you've seen how unreliable they are. A good powder thrower would be a good investment. Mind you, even the best powder thrower needs to be checked with your scale regularly. Every 10 rounds or so.
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