This is a Umarex Air Pistol known as the STEEL STORM chambered in 177BB, model 2252155.
The Umarex Steel Storm Tactical BB gun has a 30 shot capacity" with a 300-round reserve. The Steel Storm shoots as a semi-automatic" but can run full-auto 6 round bursts" too. The Steel Storm is a compact pistol powered by dual 12g CO2 capsules housed in a drop out magazine for ease of access. If you are looking for a compact powerhouse" this is it.
Features:
Semi-automatic & 6-Round bursts
30 Shot capacity
300-Round reserve
