「ダメ押しはオレがキセルを構えて気を入れた瞬間反応の無さあり得ねェのよ」
"To make doubly sure, I concentrated on setting up my pipe, and there was no momentary response." [This kinda line is sorta tricky. It's something like this.]
「『「反応すまい」とする気配さえ無い』なんてな
" "There was no hint of 'any reaction'" and such."