Semi auto failing

[mikewh]

pressure 200 bar, pellets JSB 15.9. 920 Fps.
Why does semi auto fail? Sometimes works others not. Magazine loads 2 or 3 pellets in semi auto, then fails, re cock manually then fires and sometimes continues ok others fails straightaway. Magazine seems to cycle properly. Without magazine sometimes runs semi auto system sometimes not.
Is this the gun or magazine?
If gun how does one adjust it to correct failure? Is it hammer spring tension?

Any answers anyone, shame because gun is new and really nice when working.

[Havoc]

Hi,

These are very finicky rifles and mine also does this time to time.
I would first try filling perfectly to 200 BAR then testing again and see when it does this.
I would also clean out the end of the shroud from any lead dust or debris then try small hammer spring adjustments.