Re: Is this normal? loading for my .308....
Typicaly the 308 isnt that finiky. Most of the time it will like several bullets and several powders at a wide range of charges. There are exceptions to every rule. Typicaly, optimum barrel length and twist for a 308 is 24-26" and 11-13" twists. That doesnt meen any thing else doesnt work, just that there are ussualy optimum features for a given set up. If you have a load that works well, be happy with it. If it continues to bother you, try new powders and also differant 155's. 10 twist is quite fast for a 155 and 20" is quite short. You may have better luck with 175's, 178's, 190's and 200's and medium burning powders such as VARGET, RL-15, 4064 ect...For your 155 in the 20" tube you might want to try a slightly faster powder such as BENCHMARK or RL-12 or 4320.
Hope that helps some.
PS, the 155 SCENAR is exceptionaly long for a 155, it might be more ballanced in your twist.
Long range shooting is a process that ends with a result. Once you start to focus on the result (where the shot goes, how big the group is, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.