38 SPL case necked down to .17? Found it in the woods years ago.

There were all kinds of wildcat cartridges built from the 38 Spec and 357 Mag cases. No telling what that on is without any measurements.

.22 Jet? What does the headstamp say?
-Hobbit

Headstamp says .38 SPL Its Norma brass.

Quoted: .22 Jet? What does the headstamp say? -Hobbit

The .22 Rem Jet was a 357 mag case and had more body taper. That looks like one of the other wildcats of a similar type. The neck/shoulder looks poorly done. Still pretty interesting.

Strange little round and I am darn sure it is someones homemade wildcat. No serious wildcatter would develope somethin with that little case bearing surface. Just look at how little of that case neck is holding the bullet in place.
Neck tension would vary wildly and the slightest lateral pressure on the bullet would easily push it off to one side or another.
I wonder what it was to be fired out of? A pistol? a rifle? maybe a rebarrelled .357 lever gun with a .17 barrel dropped in?
Curiouser and curioser....

After a bit of thinking maybe it was a Rem Jet variant that someone screwed up when resizing the case. That would explain the steps in the shoulder and lack of neck. Hmmm.....

That neck looks kind of nasty...

17 Jet Ackley improved  wildcat made out of 38 brass instead of 357 since the new neck would have been need to be cut down after forming.

As for the looks, someone forgot to anneal the case before sizing the neck section down, and again did a short cut by using shorter brass (didn’t have to trim).  My guess is someone needed some rounds, and one of his friends with limited wildcat knowledge made up a batch.  As for the reason you found the round, the shoulder was bulged when crimping/seating the bullet, and the round was thrown down when it didn’t fit the weapon.