Case rupture today

[jpjulian]

My grandson was shooting one of my AR's today with a Colt .22LR conversion unit. The upper was purchased from DPMS when they were closing out after they were purchased by Remington several years ago. Barrel twist is 1-8 and it is a heavy varmint profile. Ammo was Fiochi SM320 Super Match purchased at least 10 years ago. About 200 rounds had been fired. All of a sudden there was a loud report and a shout from my grandson and he jumped away from the shooting bench rubbing his forehead, he shoots lefty. He apparently was hit by powder gas from a LR case that had ruptured. Bad. About a 1/4" of case wall immediately ahead of the rim had ruptured and peeled away. That ended our trip to the range. At home an inspection of the conversion unit showed some accumulation of carbon/powder fouling but nothing unusual. Then I cleaned the rifle. Bad. I could feel an obvious bulge in the barrel about 3" in front of the chamber when pushing a patch through the bore. I surmise he had had a squib and neither he nor I heard anything wrong prior to firing the round that ruptured. Fortunately he wasn't injured and glad he was wearing eye pro. Never would I have thought it possible to bulge a heavy barrel with a subsonic .22LR, but it happened. Guess I get to order a new barrel............ Apologies for the lengthy post.

 

[js2013]

Did the squib round cycle the action? Sounds like when you cleaned the barrel there wasn’t a bullet stuck in the barrel. Do you think the bullet left in the barrel by the squib was blown out by the round that ruptured? Or I’m I not understanding this correctly?

 

[WileyG]

Possibly unrelated to your issue but 22s will develop a carbon ring in the chamber where the brass ends and the bullet begins. Pushing a patch with BoreTech C-4 carbon remover on it and allowing it to soak for a while and then brushing/dry patching will remove the carbon ring. Duration of soaking depends on how bad the ring is. A really bad buildup can cause reluctant bolt closure which could cause a case to detonate. It's a good cleaning method regardless of why it's done.

 

[J.D.Erwin]

Very glad your grandson is OK keep him shooting and safe
Jerry

 

[searcher]

Yes - glad he walked away from that. I have seen a few .22 rimfire rifles totally destroyed at the range. Don't know what went wrong but it left a real impression on me as to how "explosive" that "miniscule" round can be. The few I saw blow up did injure the shooters, despite eye protection.

 

[DGP4]

Usually, when a case ruptures like that, it is an out of battery event from a dirty chamber or other obstruction. Had that happen to me with a Remington 597 Semi auto 22LR. Blew the extractor out of the bolt but otherwise no damage.

 

[jpjulian]

Did the squib round cycle the action? Sounds like when you cleaned the barrel there wasn’t a bullet stuck in the barrel. Do you think the bullet left in the barrel by the squib was blown out by the round that ruptured? Or I’m I not understanding this correctly?

As far as I know the squib did cycle the action and chamber the round that burst. There was no obstruction when I cleaned the barrel. But when pushing the patches through, it was if the patch had been pushed out the muzzle, yet it was only about 3" into the bore. Not resistance at all for about an Inch.

 

[jpjulian]

Usually, when a case ruptures like that, it is an out of battery event from a dirty chamber or other obstruction. Had that happen to me with a Remington 597 Semi auto 22LR. Blew the extractor out of the bolt but otherwise no damage.

I had cleaned and lubed the conversion unit the night beforehand but didn't run a patch or brush through its' chamber, just blasted it with Gun Scrubber. I suspected an out of battery burst but the bulge in the barrel has convinced me otherwise. I don't see that there was any damage to the conversion unit by the burst. No matter, I'm just glad my grandson wasn't hurt by the gas or any particles from the case.

 

[Coyotefurharvester]

So you suspect a round fired, bullet left the chamber adapter and spent brass ejected. Next round fired bullet exited the adapter, previous bullet was several inches inside a barrel with a diameter larger than both bullets. And the pressure bulges the barrel and no damage to the chamber adapter, both bullets exited the barrel. Ruptured brass was still in the adapter?

 

[Ggmac]

something doesn’t add up in my opinion. Keep searching and checking .
Was this a new colt conversion or an older US military conversion ?

 

[WileyG]

Not disputing anything posted in any way but asking a question for my own education...... If there is a squib situation/complete blockage situation does a 22lr create enough pressure to cause a barrel bulge when there is also a case rupture in a semiauto weapon? Does a 22lr create enough pressure to to cause a barrel bulge in a bolt action weapon in a squib/complete blockage situation? I'm just ignorant in this area and would like to know.

 

[1b1k]

Just curious. Was this AR shot with .223 ammo before the conversion was installed?

 

[NZ_Fclass]

Usually, when a case ruptures like that, it is an out of battery event from a dirty chamber or other obstruction. Had that happen to me with a Remington 597 Semi auto 22LR. Blew the extractor out of the bolt but otherwise no damage.

I have seen a 597 in 17HMR bulge every case, as it started to extract before the pressure dropped. At night, one could see the flash in the chamber area. Combined with the magazine issues, what a load of doo-doo.

 

[nakneker]

My grandson was shooting one of my AR's today with a Colt .22LR conversion unit. The upper was purchased from DPMS when they were closing out after they were purchased by Remington several years ago. Barrel twist is 1-8 and it is a heavy varmint profile. Ammo was Fiochi SM320 Super Match purchased at least 10 years ago. About 200 rounds had been fired. All of a sudden there was a loud report and a shout from my grandson and he jumped away from the shooting bench rubbing his forehead, he shoots lefty. He apparently was hit by powder gas from a LR case that had ruptured. Bad. About a 1/4" of case wall immediately ahead of the rim had ruptured and peeled away. That ended our trip to the range. At home an inspection of the conversion unit showed some accumulation of carbon/powder fouling but nothing unusual. Then I cleaned the rifle. Bad. I could feel an obvious bulge in the barrel about 3" in front of the chamber when pushing a patch through the bore. I surmise he had had a squib and neither he nor I heard anything wrong prior to firing the round that ruptured. Fortunately he wasn't injured and glad he was wearing eye pro. Never would I have thought it possible to bulge a heavy barrel with a subsonic .22LR, but it happened. Guess I get to order a new barrel............ Apologies for the lengthy post.

I’m glad your grandson escaped harm, blessings, that could happen to anybody.

 

[jpjulian]

So you suspect a round fired, bullet left the chamber adapter and spent brass ejected. Next round fired bullet exited the adapter, previous bullet was several inches inside a barrel with a diameter larger than both bullets. And the pressure bulges the barrel and no damage to the chamber adapter, both bullets exited the barrel. Ruptured brass was still in the adapter?

That pretty well sums it up.

 

[jpjulian]

something doesn’t add up in my opinion. Keep searching and checking .
Was this a new colt conversion or an older US military conversion ?

An older conversion unit from ~1989, give or take. Out of battery makes sense, but the bulged barrel convinces me that there had to be an obstruction from a squib. There isn't a thing wrong post incident with the conversion unit and I wouldn't hesitate to use it again. With different ammo, obviously.

 

[DGP4]

I have seen a 597 in 17HMR bulge every case, as it started to extract before the pressure dropped. At night, one could see the flash in the chamber area. Combined with the magazine issues, what a load of doo-doo.

I think all manufacturers have had problems with the 17HMR in blow back semi auto rifles. That has not been an issue with the 22LR in most cases.

 

[SSchnd]

Joe glad the boy is ok. Wondering if out of battery and the bolt being soft -Not locked created the squib. Like a load not cycling the AR in Offhand but good to go in prone sling. If you have a bulge and can feel it it may still shoot but not great. Wish I had a take off back up barrel for you to swap out.
That 22lr is just such a dirty mess.
No a fan of those conversions, but the dedicated SR uppers are not cheap.

 

[SecondsCount]

Joe glad the boy is ok. Wondering if out of battery and the bolt being soft -Not locked created the squib. Like a load not cycling the AR in Offhand but good to go in prone sling. If you have a bulge and can feel it it may still shoot but not great. Wish I had a take off back up barrel for you to swap out.
That 22lr is just such a dirty mess.

I'm wondering as well as I had the same issue with Remington Golden Bullets with a CMMG conversion. The lower had an aftermarket trigger which I thought may have contributed to the issue of firing OOB.

 

[mongo chicago]

I am curious. You stated you felt the bulge as you pushed through a cleaning patch. In my experience, a bulge is obvious from the outside. I don't believe that you can have a barrel bulge that can only be felt.