This is said to be because a hinawaju was influenced by the crossbow where it was not necessary to absorb a large recoil from the gunpowder exploding and it was designed into the form where the bow part was removed.
これは、火縄銃は火薬の大きな反動を受け止める必要がなかったクロスボウの影響を受け、その弓部分を取り払った形態にデザインされていた為と言われる。