Accuracy issues on 100m with FX Impact M3 .22 (H&N Slugs)

Hello airguners,
Im new to the community and really happy to have such a plattform to share experience about FAC Airguns. I started with shooting 20 years ago but mainly with firearms.
High power airgunning is a new field for me. My equippment is a .22 FX Impact M3 with heavy superior liner, carbon fiber sleeve and tensioned liner system from Huma Air.
Actually Im using 30grs H&N Slugs with 13mm center to center accuracy on 50m @ 295 m/s.
Next test was to make shots on 100m. I was really surprised that the accuracy gone lost with a lot of flyers (70-80cm spread).
The shooting range is till 50m indoor and leading the last 50m into a channel. There is quite a big temperature difference. Up to 50m there are around 25°C, the last 50m to 100m (in the channel) is much lower around 15-17°C. Does sombody have experience with such conditions? Could this have an negative impact on accuracy?
For your support and answers thanks in advance.
regards from Germany
Markus
 
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