BillC79
Gold $$ Contributor
I recently tested temperature sensitivity of several powders against that of Varget for my .308 F-TR rifle with 200.20X bullets. The goal was to identify powders that showed similar, or better, insensitivity to temperature-induced velocity changes within the temperature range that I regularly shoot in North Central Florida (34-99° F). I have attached a summary graph of the results as an image. The full study with data and analysis is on my website at: https://wlcastleman.com/equip/shoot/varget/index.htm
For experienced shooters, much of what I describe probably falls into “rediscovery of the wheel” territory. However, others may find the information useful. So I am posting the study and results for comment and criticism.
The major findings of value to me from this study were:
1) Over the full temperature range (34-99° F): Varget and Vihtavuori N140 showed comparable temperature insensitivity
2) In the high temperature range from 77-99° F, IMR 4166 was much more insensitive to temperature-induced velocity increases than was Varget.
3) In the low temperature range from 34-77° F, IMR-4064 provided the greatest temperature insensitivity and outperformed Varget.
I will continue to revise the website over the next several weeks. Thank you in advance to those who look at the study on the website and provide comment and suggestions for improvement.

For experienced shooters, much of what I describe probably falls into “rediscovery of the wheel” territory. However, others may find the information useful. So I am posting the study and results for comment and criticism.
The major findings of value to me from this study were:
1) Over the full temperature range (34-99° F): Varget and Vihtavuori N140 showed comparable temperature insensitivity
2) In the high temperature range from 77-99° F, IMR 4166 was much more insensitive to temperature-induced velocity increases than was Varget.
3) In the low temperature range from 34-77° F, IMR-4064 provided the greatest temperature insensitivity and outperformed Varget.
I will continue to revise the website over the next several weeks. Thank you in advance to those who look at the study on the website and provide comment and suggestions for improvement.