Tokyo Marui issued a product advisory regarding an issue being experienced by some owners of the recently released Glock 19 Gen 4 Gas Blowback Pistol which they tweeted. This is machine translated:

[Important Notice] We have received the following reports regarding the gas blowback "Glock 19 Gen.4": Unintentional firing operation is performed by hitting the magazine strongly. We rushing to confirm thhttps://www.tokyo-marui.co.jp/products/gas/blowback/488e situation, investigate the cause, and establish countermeasures, and we will inform you about the details of this matter in the near future.

As soon as the countermeasure method is decided, we will provide free support, but in the meantime, regarding your "Glock 19 Gen.4", "Do not give too much momentum when inserting the magazine" Please be careful. We sincerely apologize for the inconvenience caused to all purchasers.