For 55 grain bullets I like to use H-335. Nostler has it listed as most acurate powder tested at a charge of 25.0 grains. I loaded a few at lower, to a slight bit higher than 25.0 grains to make sure the load was safe in my rifle. What I found was a huge sweet spot on my rifle of half a grain either way on the charge scale with consitantly tight groups where the POI and POA matched up perfectly.
Note for a nice cool show of jugs of water blowing up try using some Hornady V-Max. They make a heck of a show. I load the 55 grain V-Max the same COL, and charge weight as 55 FMJBT. The load shoots way more acurately whan I am capable of milking out of it.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.