As for the comments about poor performance of Varget. Some rifles have a strong preference for one load vs. another.
If the initial test with Varget does not look promising it might mean that the rifle does not like varget, so try something else - or it may mean that more load development is required before you find a Varget laod that works.
I have several thousand pounds of loading experience with RL15 and only about 10 pounds of experience with Varget. I think it is easier to get a RL15 load to shoot well than with varget, but so far, after some fiddling, I have got Varget to shoot just as well.
Varget does not react to ambient heat as much as RL15. Many of us develop our target loads in the spring, as soon as the ranges open. It is common to find shooters in August with blown primers becasue their loads were developed on cooler weather.
It is my practice to test my "pet" load with an extra grain of powder, to see if it still works. If I get pressure problems i regard that laod as too clsoe to the limit and a potentiual summer problem.
Of course, if I used Varget I would not have that problem.