Be aware of excess-pressure signs and always check for them when you change a load.
Anyways, as far as load testing, I would also record COL. When I don't like my results I'll try a couple different lengths in .003-.005" increments, each with a few powder charges. A lotta times I've gotten lucky and the 1st load works great. Sometimes it takes a couple trips out to shoot with a variety of loads. Especially when load-developing, I'd shoot either all shots cold bore or start each group cold bore. Just takes a variable away so you're not getting mixed results.