Based on my 7-08 R15 sucks for temp changes. On the Mashburn R22 seamed erratic with high temp swings but not as bad as R15 in the 7-08. Considering I'm in Minnesota my range temps vary from -25 below zero to high 90's so temp insensitivity is very important. Even though the R powders are very accurate 15 is only used with junk bullets and offhand practice and R22 only sees fire forming loads in the Mashburn.
I have high hopes for the 7977. In the next 8 months I should be able to chrono every 10 degree change from -30 to 90+.
