The reasons for this follow; in the Edo period Tsunayoshi TOKUGAWA prohibited hunting and the possession of a gun by farmers in principle; that the transfer of a gun was limited; that, commonly believed, the technological advance of guns stagnated from the influence of the exclusion of foreigners (national isolation); that a flintlock gun (flintlock system) had a stronger spring than a hinawaju and when the gunlock operating the impact was big and after trigger was pulled, the ignition mechanism for the explosive charge momentarily wavered and the accuracy of fire was bad and thus Japanese who liked to 'ippatsu hicchu' (hit with one shot), disliked the flintlock gun; that good quality flints could not be found in Japan and could not be mass-produced; and that, as a big factor, the art of gun was inherited probably in the form of a school-style gun for competitions like all the martial arts and as a result, the improvement of the weapon was necessarily avoided.
その理由として、江戸時代に入って徳川綱吉によって諸国鉄砲改めによる百姓の狩猟及び銃の原則所持禁止、銃器の移動制限がなされたことや、鎖国の影響による技術進歩の停滞という通説、フリントロック式は火縄式に比べ強力なバネが装着されており、撃鉄作動時の衝撃が大きく、引金を引いてから一瞬遅れて装薬に着火する機構のため銃身がぶれ、火縄銃に比べ命中率が悪く「一発必中」を好む日本人から嫌われたらしいことのほかに、日本では良質の火打石が産出せず大量生産ができなかったこと、またおそらくはすべての武術と同じく鉄炮術も一種の競技的な要素を含んで流派形式で継承されたため、その結果必然的に器具類の改変は避けられた、という要素も大きかった。