DD, I was hoping that you got the problem fixed. Don't give up!
I'm stubborn and like to fix things myself but by now I would be tempted to find the biggest oak tree around and wrap the 17 cal. around it.
If you send it back to the manufacturer or a competent gunsmith, you could have a "pot". $5 per guess. Each right guess gets a percentage of the pot with a 90 % payback - you get to keep 10 % for your frustration.
I'm thinking out loud here and i"m moving my lips (helps with the concentration). It's obvious that the bullets are not being stabalized properly. Possible problems: fouled bore, worn out bore, bullets undersize, bullets out of round (bad bullets, try another brand/weight/lot #), bullets being pushed to hard & not staying engaged with rifling, wrong bullet for the twist.
FWIW, I've never experienced keyholing but I think that the bore needs to be scoped.
rth1959rth