Swallowtail Jig is a classic Irish & American session tune.
This is an exceptionally common tune – for this reason, there are *lots* of slightly (or drastically) different versions. This is mine.
If your version of the melody is a few notes different, it will probably work OK with this one – as long as everyone keeps good time.
If your version of the chords is different, it may or may not work OK with this one. Best to ask.
Finger Lakes Fiddle Orchestra 