I don't load the 6BR with 55s. Mine are 1:10 and 1:12 twist. Never shot anything smaller than a 80 Berger. However, the 6mmBR site is a great resource. These pages have many proven loads and good general info. Didn't see H380 on the loads, but this my give you an option.
Luck, Tim
http://www.6mmbr.com/6mmbr.html
http://www.6mmbr.com/varmintloads.html
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