Vbshootingrange: One of my closest friends and Hunting partners DESTROYED his Ruger 77/17 V/T in 17 HMR about 28 days ago!
He was shooting some older "blank" brand of 17 HMR ammo and was sighting in for the upcoming Varmint season.
He had on both ear muffs and ear plugs (we shoot from inside a shooting shed and he was checking some centerfires that morning also).
He "thought" he heard a light report but fired into his 100 yard target again anyway.
His gun blew up on this next shot!
The laminated gray Varmint style stock split in three large pieces, his two glued end to end Ruger ten shot rotary magazines were both destroyed and damage was done to some springs in the bolt/action!
In addition he had ten small bloody spots on his face - caused we think from plastic and plywood splinters.
The ammo company took full responsibility and bought him a new stock and two new magazines and had Clark Custom do the repairs.
The ammo company also replaced his ammo and reimbursed him for shipping coming and going for the Rifle.
The barrel, somehow, was NOT damaged!
The Rifle is back in his hands now and shoots as well as before (which is VERY well!).
The ammo company gave him the "lot numbers" of their questionable ammo.
Apparently the split necks he was getting, ON OCCASSION, cause one of two problems bullets stick in the barrel when incomplete combustion occurs in the chamber - but SOMETIMES this condition will cause a detonation in the barrel that blows back into the chamber/magazine areas.
I had to leave just after the Rifle was harmed but got to see it first hand along with the remnants of his glued together magazines!
It scared me!
The Clark Custom people took two bullets (17 grain slugs) out of my friends barrel.
I am not sure if your problem is the fault of the ammo or of a problem with your gun but I would NOT let the little one shoot that Rifle anymore until all questions are answered.
While I was just away to the west coast two of my Ground Squirrel Hunting buddies (one from New Hampshire and one from Iowa) were here and put thousands of rounds through their Volquartsen semi-auto 17 HMR's.
Both eventually had lesser "blow-ups" that put both Rifles out of commission!
I did not get to see or speak with them in person about their incidents.
Worrisome this turn of events.
Good luck to you.
Hold into the wind
VarmintGuy