Well done for asking if you are unsure.
I am a bit confused by your dimensions here...
Is that COAL of 3.011" and case length 2.1565" ?
The Hornady data shows COAL as 2.905" for that bullet and 2.115" for the case length
KISS.
I recommend that you just stick to simple and just use the COAL recommended by the manufacturer's load data, especially if this is your first foray into reloading...I have been reloading for a few years and while I am obviously not in the league of competitive target shooters my 5 shot groups have averaged 0.850" over a few hundred groups with most bullets from a light stalking barrel...all at manufacturer's recommended COAL.
I compare both the bullet manufacturer's and the powder maker's data. Using the COAL from the bullet maker's data especially if the Powder maker's data doesn't list that particular bullet.
That is the powder charge range Viht give for a different bullet Norma HPBT isn't it?
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I usually go for the powder manufacturer's load range because that is up to date with powder available to purchase... but in this case the Hornady data from their 9th edition reloading book gives a much lower powder range for Viht 160 starting at 33.4gr with 43.6gr as max...so it is even more important that you don't just choose a random "halfway up to start"...apart from safety...what if the best load for your rifle is in the lower half of the Hornady powder load range?
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I notice @Foxyboy is referring to 6.5x55SE and you are referring to 6.5x55 sm so forgive me if I have confused the issue by looking up the wrong tables....do your own research of course and don't rely on some bloke like me on the internet...
Alan