Many years ago someone handed me a Diana Grade Browning O/U Trap gun (unmentionable mentioned to make point, no offense intended.) I shot 50 straight with it. Well above my average.
I have picked up a new flintlock and shot the lights out with it first time out. This has happened more than once.
I shot a small bore match with another shooter's rifle as he was struggling. All tens and Xs.
Never has Round Two been as successful as the examples above. It is referred to in match shooting circles as "new gun syndrome." For your entertainment, here is a link to a discussion about the syndrome.
"New Gun" syndrome...
ADK Bigfoot