Having spent my day shooting a modern iron sighted rifle offhand I would say you are a damn good shot.
Some days it's better to be lucky than good. As this unfolded the soft 6 o'clock breezed turned to puffy 1/4 value winds switching from left to right and back, maybe 10 mph with occasional gust of about 15 came thru. It was fairly predictable in the cycle so I just waited for the tailwind to return and didn't dawdle around with the shot.
That said, I have another group shot a few years back with a .45 flintlock that pleases me more. 50 yards, also offhand.
Just my opinion, but for me scopes complicate offhand work a bit and I much prefer an aperture for that endeavor. I've done it both ways with a variety of guns...prefer irons if that is possible.