Status-6 (Twitter)

A Soviet-made M240 240mm heavy mortar is indeed being used in combat by the Ukrainian military.

Photos below show a M240 mortar deployed in the field and the shell it is firing.
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@Archer83Able:
Ukrainian media outlets are sharing this photo of a Soviet-made M240 240mm heavy mortar allegedly being employed by the Ukrainian military in combat.

The only known place of storage of this weapon after 1991 in Ukraine was museum. https://t.co/eRYjlNfYXe

🇺🇦 Ukraine Weapons Tracker (Twitter)

#Ukraine: More photos of that ancient but powerful M-240 240mm mortar in use with Ukrainian forces. As can be seen it is used with 53-F-864 HE FRAG mortar bombs - each weights 130kg, packs 32kg of explosives and can be fired as far as ~9.65km.
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@UAWeapons:
#Ukraine: For the 1st time the AFU deployed an ancient but powerful M-240 240mm mortar, which was adopted by the USSR in 1950.

Interestingly, the M-240 was not previously known to be in Ukrainian long-term storage, however a mortar of this type was displayed in a museum in Kyiv. https://t.co/0Uo8BkAoKu

Necro Mancer (Twitter)

Обуховский р-н, Киевская обл., из воды достали куски неведомой херни https://xn--r1a.website/dsns_telegram/10265 #гсчс