Airsix TV goes over the RST SI SMP Steel Slide and Out Barrel set which is a high-end airsoft upgrade designed to fix the poor reliability of the base VFC SI SMP pistol, which the he notes quickly becomes unusable in its stock form. The upgrade set uses real-steel materials and finishes, including 17-4PH stainless steel with H900 heat treatment and Black Nitride for the slide, and SUS 416R stainless steel for the outer barrel, ensuring high durability and a realistic look.

In terms of performance, the upgraded pistol demonstrates excellent recoil—likely the best achievable on the SMP platform—and surprising gas efficiency, allowing for around 100 reliable shots even with the added weight of the steel slide. Airsix tvconfirms the set resolves the underlying mechanical issues, especially when paired with the separately purchased "Performance Kit." This kit addresses deep-seated flaws in the base gun's hammer and knocker mechanism.

The primary drawback is the significant cost, as the steel slide set, outer barrel, and the necessary Performance Kit—which is crucial for correcting the base pistol's faults—combine for a high overall price. Despite the expense, the upgrade successfully transforms the SMP into a durable and high-performing pistol, making it a viable and satisfying option for serious airsoft users.