ka m4a1 問題

話說,小弟今朝操鎗果陣發覺個bolt receiver 唔夠力推匣,個bolt receiver 回唔晒全程搞到射兩野又停射兩野又停 個飛機都好似唔可以同bolt receiver 同步行程仲有開鎗果陣聽到彈弓果d發發聲係條尾通度又屬唔屬於正常呢?
仲有條尾通好似過長咁,扭到盡後頂實左頂住buffer粒pin,但係唔可以將bolt receiver 暢順地塞返入個身 好似有問題咁
若果要執好佢,又應該換咩,執咩,搞咩位呢?請求各師兄教路!