Shooting results question

[Oregonair]

I shot my Pro Sport .117 yesterday and had some interesting results I’d like to share. Shooting at 2700 ft elevation, clear sky, around 60 deg F, light to no winds, shooting at 35 yards from sand bags. Shooting from mid to late afternoon with barometric pressure dropping (I didn’t note the pressure but I received a storm alert on my watch indicating a pressure drop of at least .075” over a 3 hour period). Temperature dropped maybe 3-4 degrees over that time period. As you can see my first 20 shots grouped 1/2” higher than my last 10. Can a slight drop in barometric pressure/temperature cause this kind of result?

[TenMetrePeter]

Drop in pressure on its own would lead to less dense air and presumably less air drag leading to less drop. The opposite.
So presumably what came with it made the difference ie higher humidity to increase drag and lower temperature to increase gun grease viscosity.
Maybe.

[Oregonair]

Peter, I hadn’t considered the grease but that could be a possible factor. Could definitely change velocity.

[Blackbaronfish]

Its the same result as shooting your first 5 shots before your rifle warms up. So i would say it was temperature on the grease/workings.

BBF

[Oregonair]

I really have no idea what kind of grease I have on my rifle parts or it’s properties. I think I’ll have to do a little research into this and see if what I have been using is a good one to use.