ガス遅延ブローバックとか採用せんの？
最近じゃワルさーCCP(Conceal Carry Pistol)なんかで
使われてて+P弾なんかも大丈夫そうだし樹脂製多用で
HK P7で問題になった過熱もある程度おさえられるらしい。


https://www.google.com/amp/s/www.thetruthaboutguns.com/2015/01/jeremy-s/gun-review-walther-ccp/amp/
https://cdn0.thetruthaboutguns.com/wp-content/uploads/2014/12/CCP_Lead.png
https://cdn0.thetruthaboutguns.com/wp-content/uploads/2014/12/P7_Diagram.jpg

The polymer frame insulates the shooter from the heat generated by the gas system,
and the large metal block seems to soak it up and then transfer it upwards towards
the barrel. Eventually I found the sides of the slide on either side of that block were
getting toasty, but they never got more than noticeably warm.

元々は七ミリクルツ撃つ国民突撃銃用に開発された
機構やし(ものによってはMP43と同程度の命中率)
九ミリ弾なら問題なく使えるのでは

https://en.m.wikipedia.org/wiki/Grossfuss_Sturmgewehr
https://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Grossfuss_Sturmgewehr.jpg/1280px-Grossfuss_Sturmgewehr.jpg
↑良い方の国民突撃銃