Just Right Carbine explosion

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Hey everybody,
Just heard back from JRC. They said the issue was using too short a buffer tube. I needed the longer buffer tube for their 40cal conversion. The interesting thing is that the conversion kit did not include the buffer tube. So I just used the one that was in my original 9mm version. That was a mistake.
While I had the mishap in October, it took me until late December to send it in to them. So, it was just a little over a month turn around in what was probably a very busy time of year for them.

So, they put a new buffer tube in, magwell, bolt (since the other cracked) and included a new magazine. They are shipping it back today. They did charge me $125 for the fixes and shipping back. No problem with that. They were very professional and easy to deal with.

As I am typing this I wish I asked them a few more questions. One of which is can I use that longer buffer tube with my original 9mm parts? Or will that cause another problem. I don't want to ever replicate that explosion again.

I will let everybody know how it shoots once I receive it back.
 
Hey 243winxb, Thanks for that link. This is the first I have seen of this. The 40 cal kit came with some buffers. I could not fit it in the buffer tube when I was putting it together before the explosion, so I left it out. Another ignored signal of something wrong on my end.
I also guess this is why they had to charge me for some of the parts etc. It seems that I technically violated the warranty.

This incident has been quite the educational experience. Lot's of ignored warnings through out the whole process by me.
 
I am late to this but was just going to say contact JRC! They are great with cusomer service... I had an early one in 9mm I got second hand and other than shipping it was free... I also added the quick take down to mine while it was in. I have not put a lot through it but it was working great... its a decent rifle - I got it before the AR9's were realistic in price for me... and with this madness she will work fine sharing my glock mags I figured they would help you! It is amazing that nothing was damaged with the rifle...
 
Mk VII said:
So it was opening too soon?
Click to expand...
Hey Mk VII, That is my guess. I was so happy to have the weapon sent back I did not ask enough questions. Since the buffer tube I was using was too short, it makes sense that it was opening too soon. But, I would just be guessing.

It's funny. I have put together a half dozen AR's from scratch and done a good bit of minor gunsmithing on old pistols and thought that I new a lot about the AR platform and other weapons. This incident shows me that I don't know the inner workings of the platform near as good as I should.
The old saying of "You don't know what you don't know" is absolutely correct.

I gotta admit that I am a little gun shy right now. (pun intended). Ignorance is not bliss when you are talking about firearms. Ignorance can be deadly.
 
MySuomi said:
Since the buffer tube I was using was too short, it makes sense that it was opening too soon. But, I would just be guessing.

It's funny. I have put together a half dozen AR's from scratch and done a good bit of minor gunsmithing on old pistols and thought that I new a lot about the AR platform and other weapons. This incident shows me that I don't know the inner workings of the platform near as good as I should.
The old saying of "You don't know what you don't know" is absolutely correct.
Click to expand...

I am in the same boat. Why would the length of the tube matter?
The buffer weight yes, the spring rate, yeah, but the length of the tube? I too am at a loss.:confused:
 
chris in va said:
What does a new round look like manually dropped into the chamber?
Click to expand...
Chris,
I got the gun back via UPS yesterday. Plunk tested it. Round looks fully supported. But, it also looked that way before the explosion.

I will upload a picture later. The replacement buffer tube is at least an inch longer than its predecessor. Will shoot it Saturday to test.
 
MySuomi said:
Yes, it was factory ammo. And i don't think anything else is missing from the bolt. When I get home from work I will compare the cracked bolt to the original 9mm bolt.

This could have been much worse. I was stunned for a few seconds after the "explosion". Then I counted all of my fingers. :)
Click to expand...
Yes was just there, blew the magazine out of my 9mm Just right. Ya sit there, wait for the pain, just chillin' then survey the damage
 
This reminds me-

-to rotate the 9mm rounds always kept in the magazine, which is used for my Walther P99 carry gun.

I suppose that the bullet compression (if the same round is kept on top) is very gradual, but might be very difficult for the untrained eye to notice.
 
You screwed up bad and this was totally your fault, glad you were at least honest about it. God bless and please be more careful next time lest you kill yourself or worse, others.
 
Demi-human said:
I am in the same boat. Why would the length of the tube matter?
The buffer weight yes, the spring rate, yeah, but the length of the tube? I too am at a loss.:confused:
Click to expand...

Agreed. Why make the design change the buffer tube length rather than the reciprocating mass weight and spring weight is an odd one.

I don't know the design, only researched it an elementary amount a year or two ago, but it seems they should have borrowed from the AR and other blowback platforms in that the reciprocating mass changes to match the cartridge and that is it.

@MySuomi glad you are ok and thank you for letting everyone learn from your mistake, so many people would've just saved face and not returned to tell the whole story or just make something up.
 
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I have not had any trouble with my JRC since its return. I have left it with the 40 cal conversion installed. After my debacle, I am gun shy (pun intended) from switching back and forth to 9mm. I will leave it at 40.

I just don't have an adequate understanding of tube length and its effect on bolt closure. Until I get better educated I am not experimenting with this JRC.
 
I'm confused, I justed looked over the JRC website for about 20 minutes including watching the caliber conversion video and instructions and I can't find any mention of needing to change the buffer tube or buffer weight. It just says if your conversion came with a new buffer tube that you need to use it, but you said your conversion did not come with a new buffer tube right? Did you also have to change the buffer weight with the longer tube? Normally the opening on a blowback firearm is tuned by changing the weight.
 
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