I know from experience that too many shooters and airgunners not familiar enough with airgun ballistics, especially TERMINAL ballistics, would imagine your .30 caliber capable of clean kills on coyote-sized targets with chest shots. Not so!
You did it right, Brother. The brain shot dropped him flat, with absolutely NO conscious suffering to your prey. Even with a perfect chest shot, the animal(s) would suffer indescribable panic and trauma for anywhere between their last few moments to last SEVERAL MINUTES (or more).
Good show! And congratulations on an excellent airgun trophy. I'd definitely have him mounted to commemorate the memory.