The Heckler & Koch HK417 D Gas Blowback is a full-size airsoft replica engineered to deliver realistic mechanical behavior and stable sub-1-joule performance. Designed around a reinforced gas system, it reproduces the characteristic recoil impulse and bolt movement expected from a heavy-caliber rifle platform, offering a highly immersive experience suitable for advanced training simulations and structured recreational use.

Its external construction features a full aluminum housing, which provides rigidity and solid structural alignment, while the stock and pistol grip are crafted from impact-resistant polymer to achieve balanced handling without excess weight at the rear. The extended handguard incorporates a full rail system, allowing attachment of optics, lights, vertical grips, and other accessories commonly used in modern rifle configurations.

The HK417 D includes an adjustable mechanical diopter sight, enabling fine windage adjustments for precise shot placement. For users relying on optics, the sights can function as backup references without obstructing the sight picture. The internal gas-driven mechanism offers consistent cycling with reliable blowback action, keeping the firing feel stable despite the rifle’s large frame.

Equipped with a detachable magazine holding 20 rounds, the rifle maintains a realistic ammunition count while ensuring dependable feeding under both semi-automatic and full-automatic fire, depending on the selected mode. The adjustable hop-up unit provides control over BB trajectory for improved accuracy with 0.20 g BBs, the recommended weight for optimal performance.

At an overall length of 808–888 mm and with a weight of 3705 g, this replica mirrors the proportions and heft of the real HK417 platform, resulting in natural recoil management and stable shouldering. Its design emphasizes durability, mechanical realism, and compatibility with accessories, making it suitable for training scenarios where authentic ergonomics and consistent function are essential.