17 hmr Detonation in Chamber

[cervus]

Interesting moment whilst zeroing the 17 HMR Marlin..having shot and adjusted my scope as necessary,took the next shot and the round detonated in the chamber! A loud report and smoke seeping from the chamber and rear of the bolt with a mild blast in my face.Marlins have a strong action fortunately...I am familiar with cracked cases but that is another matter to do with the quality of the case metal, this was different chronic overpressure in my opinion ,luckily I had my shooting glasses on ...the gun was moderated

 

[DazT]

All previous rounds sounded ok and hit the target??

 

[Dalua]

Sounds more like acute overpressure, rather than chronic.

It would be interesting to know what caused it, though. As Daz asks, did the bullet from the shot before the high-pressure one definitely hit the targets somewhere, or might it have got stuck in the barrel?

 

[cervus]

Hi Gents ,yes all good prior to...acute was a better word !

 

[A Guy Out West]

What was the ammo brand?

 

[JTO]

did the bullet from the shot before the high-pressure one definitely hit the targets somewhere, or might it have got stuck in the barrel?

=my first thought.

 

[cervus]

What was the ammo brand?

Hornady 17GR V-Max

 

[oxfordshirestalker]

Fully possible that the previous bullet got stuck up the spout. I had exactly this the other week, it still made a fair pop and I only thought to have a look because I'd read things on here/nothing hit the target. The bullet was stuck about half an inch into the rifling.
Plenty of stories of people loading another round behind a stuck bullet and the above happening.

 

[Cottis]

Sorry but I am not fully understanding what happened here.

Are you saying that you cycled the bolt, pushing a fresh cartridge in to the chamber with a confirmed fully clear barrel, pulled the trigger with the round going bang but the bullet not exiting the bore and the action taking the brunt of failure but it would seem (thankfully) in a fairly safe way?

Did the bullet leave the barrel and hit the target? If so, I cannot understand what you mean.

Could the bolt have not been closed but the round somehow went off. It doesn't sound like you had been shooting tons and tons of shots, so the chamber was not red hot.

Was the barrel clear post failure?

 

[I. Farticus]

Hi Gents ,yes all good prior to...acute was a better word !

I'm afraid "holyf*cksh*tb*ll*cks" would've have been my word!

 

[Cyres]

I was talking to a senior Eley rep last month about .22 lr ammo and we strayed onto .17 HMR. When asked he said all .17 HMR ammo was made by one manufacturer irrespective of what the brand on the box states.

If its CE marked then inform your local trading standards. Duff .17 HMR rounds are normal. Please search on SD for very long thread on this very issue.

D

 

[cervus]

Sorry but I am not fully understanding what happened here.

Are you saying that you cycled the bolt, pushing a fresh cartridge in to the chamber with a confirmed fully clear barrel, pulled the trigger with the round going bang but the bullet not exiting the bore and the action taking the brunt of failure but it would seem (thankfully) in a fairly safe way?

Did the bullet leave the barrel and hit the target? If so, I cannot understand what you mean.

Could the bolt have not been closed but the round somehow went off. It doesn't sound like you had been shooting tons and tons of shots, so the chamber was not red hot.

Was the barrel clear post failure?

Ithink that I am going with the lodged bullet theory ! It all correlates as I had a squib shot from this batch,also did not see a round strike ....barrel was clear after the event. Happier now .....thanks guys for your input!

 

[VSS]

Ithink that I am going with the lodged bullet theory ! It all correlates as I had a squib shot from this batch,also did not see a round strike ....barrel was clear after the event. Happier now .....thanks guys for your input!

Lesson learned? Always check the barrel after any suspect round!

 

[cervus]

Lesson learned? Always check the barrel after any suspect round!

The squib round was 10 rounds before the event!

 

[VSS]

The squib round was 10 rounds before the event!

I was responding to your comment that you didn't see a round strike - I presumed you meant the round previous to the one that blew back, as you say you're going with the "lodged bullet theory".
Therefore, having not seen a round strike you should have checked the barrel, I would say?

 

[25 Sharps]

Get a WMR....

 

[Grandhubert]

It is also possible that the round was not fully in battery but was fired nevertheless.

Any chance of a photo of the case?

 

[cervus]

I have discussed this issue with a ballistician who examined the case and it is apparent that the round base split and the energy of the rearward ignition in the chamber is what caused the detonation,the cases normally split at the neck so an issue with the base of the round...good old quality control problem..for the record I always check the barrel post squib also at 100m you don,t always see the round strike at that range with 17 HMR....anyway that is that and I may get a 22WMR!

 

[Dalua]

Is the ballistician thinking that a flaw in the case-head caused it to let go under ordinary service-pressure?

My understanding is that the usual reason for these events is:
1. Poor annealing (or something) leads to crack in the case-neck.
2. Crack in case-neck admits moisture, contaminating powder-charge
3. On firing, incomplete ignition of charge lodges bullet in barrel ('squib round')
4. Bullet from next round meets barrel obstruction
5. Resultant over-pressure causes the case to rupture.

 

[ChesterP]

Yet another advert for not owning an HMR, which joins hundreds of others where owners had similar lucky escapes. Glad I sold mine (which I did after getting one too many squib rounds). Ammo currently cannot be made which avoids split necks at manufacture due to detonating compound/rim forming being done early on in the process meaning that cases cannot be annealed prior to neck forming. QC is meant to pick up damaged cases but plenty get through. Some people never have a problem. Many do. I wouldn't take the chance now. Russian Roulette isn't something I like playing. That and batch consistency was pretty awful, at least a couple of years back when I still used mine. Glad you're ok Cervus.