Re: What Would Happen?
I'm not up on the 17s, but if I remember right, one is a necked down 22 magnum and the other is a necked down 22 LR. Right? So, if the one you are talking about is the necked down 22 LR, it would fire, the 17 caliber neck would expand to 22 caliber (to fill the chamber), and the bullet would go speeding down the barrel. It might bounce around a little on the way down, or it might just go zipping down the middle, not touching anything.
Accuracy probably would not be very good.
If you mean would it be dangerous - no. Kinda wasteful, though, when you consider how expensive them dang things are compared to Long Rifle shells.
I base this answer on having shot 38/40s in a 44/40 revolver. Same basic thing. 38/40 is a necked down 44/40. Brass expanded to fit the 44/40 chamber, and I hit my target at about 25 feet, with a five-shot group that could be covered with my hand. Not great accuracy, but I coulda killed somebody with it.
Meddle not in the affairs of dragons, for thou art crunchy, and taste good with catsup - George of Lod, Year of Our Lord 297
I always take precautions.
Beware the Evil Bullet Fairies.