bore inspection, potential chamber failure

[joepistol]

Thanks for posting this story..not very often that this is found / reported.
I too am curious as to chambering of rifle,( caliber) as well as other pertinent information..
How old is rifle ? any idea of # of rds. fired, before finding the defect ?
How / why did you find the defect ? Something happen that made you grab a bore scooe ?
Factory loads or hand loads used ?

I doubt that any ammo would result in the observed damage.
My guess it's a material defect of some sort.
Nice that the barrel ? rifle ? is going to be replaced.
Please post some follow up info as it becomes available.

[AleksanderSuave]

No problem, happy to share info as they requested the same info on it.

Its the carbon/black steel barreled Tikka T3x CTR 6.5 creedmoor in 24" 1:8 rifling. Basically the plain jain model. 7 months old when this happened, I was shooting it an average of 2x a month, so it did see some fairly regular use. As far as I know I am the first person on any forum to have posted a defect like this. I have searched accurate shooter, snipershide, reddit, facebook, rokslide, and a handful of other smaller ones. I think this is an anomaly to the overall Tikka typical quality.

round count (approx 700-800 rounds, may be forgetting a few boxes when I was chasing this issue).
Berger Hybrid Target 140 grain: 100 rounds
Federal Gold Medal Sierra Match King 140 Grain: 200 rounds
Federal Gold Medal Berger Hybrid Target 140 grain: 200 rounds
Hornady ELD Match 140 grain and 120 grain: 100 rounds each

all match ammo, no handloads ever shot, funny enough, my buddy loaded some for me, and they've sat here, kept forgetting to grab them off my office desk to throw in the range bag.

3 symptoms specifically started around the same time, that caused me to investigate.

1st symptom (came before all the others) - bolt was sticky after shooting a few rounds, or extended shooting, tried lubing, disassembly, clean and regrease no change in behavior. Fine when cold or cycling empty. As it warmed up it got bad. This was gradual and got exponentially worse, it started with a "after a few hours of shooting" to eventually "after an hour of shooting" to "after a box of 20 rounds" to "after 5 shots". Easy to mistake for dirty rifle due to the gradual timeline.

symptoms 2 and 3 came at around the same time, and what caused me to really dig into it.

symptom 2: increasing heat of the barrel. Alarmingly hotter than normal. I was swapping bipods and the rifle rolled onto my hand and gave me a second degree burn from just touching it.

symptom 3: significant POI shift. This was a rifle that shot 0.24 MOA groups at 100 yards, then went to not being able to shoot a string of 3 shots within 1 inch. POI would shift up/down/left/right with no rhyme or reason. Shots would spread apart and open up even worse as the rifle got tested. On cold bore it would maintain just about an inch with match grade ammo, maybe less, after having shot .5 moa groups average even with junk ammo in the past.

I tried 2-3 deep cleanings, carbon killer soak, etc. and eventually bought a borescope after the cleanings made no difference.

I used this borescope: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 (two of them actually), one through each end, to find 2-3 largely pronounced cracks inside of the chamber. Originally they looked like a hair inside it, but I verified with sticking a cleaning brush in with a camera on the opposite end that it was not a hair or any other item.

[joepistol]

Thanks for answering my questions. Interesting findings.
Sometimes things happen & you never will have an good explanation "why"
i.e. see my thread I just wrote titled "strange ammo fail @ the range." in the "General Firearms Discussion" forum

I looked @ the bore scope in your link..seems like a reasonable price for a handy tool.
Thought about ordering one.
Then thought, I'll drive myself crazy, looking for defects in all my firearms.
maybe ordering one wouldn't be such a good idea.