If I was doing this, I'd take it to extremes: "He heard the 'snick' of the revolver's safety as the baddie slid a fresh magazine into the handle, followed momen

If I was doing this, I'd take it to extremes: "He heard the 'snick' of the revolver's safety as the baddie slid a fresh magazine into the handle, followed moments later by the click-click as the bolt shot home. He knew he still had a few moments while the baddie nestled the stock against his cheek, taking care not to catch his fingers on the bayonet lugs". There, that should do it.