I've got a 647 in .17 HMR that will split the necks of just about every fired case, probably around 80%. If any of you guys have one of these I'm curious if this is the nature of the beast or if there is something going on with the gun. The gun is superbly accurate, dime size groups at 25 yards. I'm inclined not to worry about it but I am curious if they all do this.
Thanks!

Ive shot mine quite a bit and havent had anything happen as you described. You might want to either try a different brand of ammo and if it still happens , send it back to smith.

I've put hundreds thru my own 647 without any splits. Great pistol, no issues.

__________________
Dum vivimus Vivamas

I'm guilty of not shooting mine more but I haven't had an issue yet.
Consider another brand or different lot of the same ammo and IF it is ammo[brand or lot no.] related I'd contact the manufacturer with the info.
Might get same free ammo - who knows. It won't hurt to try.

I have read of 17 HMR case splits on different forums but your's sounds excessive. Im thinking it needs to go back.

Mine has never split a case. I would be leary of sending it back to S&W as they probably don't have extra cylinders and might not want to send it back to you if they thought there could be a legal problem in the future.

__________________
Ken

Try different ammo first, as mule88 posted. I had a similar problem with some Remington ammo in a Savage 93R17. Switched ammo around, no recurrence of the splits. The consensus over at Rimfire Central is a bad ammo lot is most likely the cause of split cases. It is the easiest to rule out.

My cases looked like this:

__________________
Bob

That is just what my cases were looking like. I was shooting CCI ammo, so I guess it's time to try something different.
Thanks for all your input!

I've shot Hornady, CCI and Remington and had no problems.

Good luck.