Developer only gun. Tier 12, and created by Rudy.
Think of this as a historical, IRL hybrid counterpart of the in game H-2 Ares and 75mm QOLOP (but Soviet, longer, and at a smaller caliber)

Rudy actually has posted information and images of this gun on his X (Twitter) account, and you can check it out yourself here: https://x.com/RudyTheROP/status/1873775492706570473

Historical Notes:

The 85mm Strela AK was an experimental Soviet ultra-high-velocity tank gun developed from 1957–1959. It used specialized "star-tray" sub-caliber ammunition designed to achieve extreme muzzle velocities of 2,000–3,000 m/s. The original gun was ~13 meters long but was later shortened for potential use on ISU casemates and the Object 279.

2 prototypes later, & the Strela project was eventually cancelled. Poor accuracy, rapid barrel wear, & the complex ammunition made it unviable for production. The final nail in the coffin was the advent of APFSDS rounds for conventional smoothbore guns.