The first shot may have been because of a clean cold barrel.
Since 1988, I have used 180 grain Nosler Solid Base pushed with 44 grains of H-4895 after reading of Wendell Swank. He collected game specimens in East Africa using his '06 with 48 grains of 4895 and 150 Sierra spitzers for the smaller animals and 44grs.4895 and 180 Sierra spitzers. His bag included kob, wart hogs, hartebeest. lion, buffalo, and hippo. So I figured it would work as well here in N. America and it has.

Shew me thy ways, O LORD: teach me thy paths.
"there are few better cartridges on Earth than the 7 x 57mm Mauser"
"the .30 Springfield is light, accurate, penetrating, and has surprising stopping power"