"both barrels" meaning in English

{
  "etymology_text": "In reference to discharging both barrels of a double-barrelled shotgun simultaneously rather than one at a time.",
  "head_templates": [
    {
      "args": {
        "1": "p"
      },
      "expansion": "both barrels pl (plural only)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English pluralia tantum",
          "parents": [
            "Pluralia tantum",
            "Nouns",
            "Lemmas"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "to give someone both barrels",
          "type": "example"
        },
        {
          "text": "to let someone have both barrels",
          "type": "example"
        },
        {
          "text": "to hit someone with both barrels",
          "type": "example"
        }
      ],
      "glosses": [
        "The maximum damage that a weapon can deliver."
      ],
      "id": "en-both_barrels-en-noun-6il5MGH4",
      "links": [
        [
          "maximum",
          "maximum"
        ],
        [
          "damage",
          "damage"
        ]
      ],
      "raw_glosses": [
        "(informal, figuratively) The maximum damage that a weapon can deliver."
      ],
      "tags": [
        "figuratively",
        "informal",
        "plural",
        "plural-only"
      ]
    }
  ],
  "word": "both barrels"
}

{
  "etymology_text": "In reference to discharging both barrels of a double-barrelled shotgun simultaneously rather than one at a time.",
  "head_templates": [
    {
      "args": {
        "1": "p"
      },
      "expansion": "both barrels pl (plural only)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English informal terms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English pluralia tantum",
        "English terms with usage examples"
      ],
      "examples": [
        {
          "text": "to give someone both barrels",
          "type": "example"
        },
        {
          "text": "to let someone have both barrels",
          "type": "example"
        },
        {
          "text": "to hit someone with both barrels",
          "type": "example"
        }
      ],
      "glosses": [
        "The maximum damage that a weapon can deliver."
      ],
      "links": [
        [
          "maximum",
          "maximum"
        ],
        [
          "damage",
          "damage"
        ]
      ],
      "raw_glosses": [
        "(informal, figuratively) The maximum damage that a weapon can deliver."
      ],
      "tags": [
        "figuratively",
        "informal",
        "plural",
        "plural-only"
      ]
    }
  ],
  "word": "both barrels"
}