Robinson Arms XCR. 223 - Bolt carrier blew up **UPDATE**

In the event of a catastrophic case failure with the breech locked, the high pressure gas will escape. A blown out magazine, and blown away extractor are to be expected. Receiver damage will depend on how the gas vents off.
Once the case fails, pressure drops to zero, essentially instantly.
It is odd that there was still sufficient gas port pressure to unlock the action, assuming that when the smoke cleared the action had unlocked and was opened, and that the damaged bolt carrier was able to effect unlocking.
 
*MALICE* said:
Sorry Savage, still not possible with an XCR or AR15. The firing pin won't be able to reach the bolt face unless it's locked (as previously stated many times). The barrel doesn't/can't unlock due to pressure alone, only once the bullet passes the gas port and siphons gas back to hit the carrier. The carrier moving rearwards turns the bolt, unlocking it. If you removed the carrier and just used the bolt to lock the round in place, and hit the firing pin, the bolt would stay locked.



Don't know about the M1 or M305.
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While this is true if we are talking about being majorly out of battery, say more than 0.100; I don't believe it is true if we are talking about partially out of battery - ie: let's say 80% or 75% or 70% lug engagement. There is enough slop in the system that the gun could easily be 0.020 or 0.030 out of battery with partial lug engagement and still have the carrier/bolt aligned sufficiently to allow firing pin engagement. I've personally seen two AR15s blown up this way. I've also seen a few M1 Garands & M1A rifles go boom because of partially engaged bolts.

While the garand style bolt carrier/firing pin safety designs are somewhat different, the same principle is in play - ie: the bolt is not completely closed and despite the designer's best efforts to engineer a system that makes it physically impossible, there always seems to be enough slop that under the right circumstances it is possible. I will concede that the bolt carrier/bolt design of the AR15 and XCR is better than that of the earlier Garand style systems, but certainly my experience has been that their out-of-battery-safety-features don't always work as well as we would like.

Cheers,

Brobee
 
I would be more inclined to believe that the rifle fired out of battery, most likely the firing pin was stuck in the out position. When the round meets resistance in the chamber it goes off prior to locking up. I had this happen to me on a Johnson 30-06 and the rifle came apart in my hands. Rigrat
 
I would be more inclined to believe that the rifle fired out of battery, most likely the firing pin was stuck in the out position. When the round meets resistance in the chamber it goes off prior to locking up. I had this happen to me on a Johnson 30-06 and the rifle came apart in my hands. Rigrat
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I don't know how else to explain this to everyone. THE FIRING PIN WILL NOT EXTEND PAST THE BOLT FACE UNTIL THE BOLT IS ROTATED TO THE LOCKED POSITION! PERIOD. FULL STOP.
The gun is designed that way to avoid out of battery ignition. Unless the end of the firing pin is broken and jammed protruding from the bolt face, it can't happen.

By the time the pin can extend past the face of the bolt, it is already fully locked. The bolt carrier has approximately .06" of forward travel past the point of full lock-up to avoid the issue.
 
I will admit that I know nothing of the AR platform, so I will rely on the advice provided by Malice.

Since it is not possible to fire out of battery. Then there are two issues which need resolution in understanding the event. Firstly there is the damage to the cam lock and the damage to the receiver (the little nick). Secondly, there is the issue of how the casing, in the neck and shoulder area, managed to fold and wrap into itself as shown on the picture.

The Op suggests that the correct amount of powder was used. I used to own a new Remy pump in 243. That thing blew second fired casings like nobody's business. My 223 (bolt) split a few casing necks open too.

In all instances, the bullet was ejected down the barrel and the escaped gas discharged itself out the opened orifice. This case did not fail, it was violently exploded open.

Malice, if one assumes the powder charge was dangerously hot and the rifle fired while in battery, could the force of the exploding casing pushed back the bolt outside of the gas system orifice up the barrel? Could the combination of the gas from the exploding shell and up the barrel have actually activated the gas system to bring the bolt out of battery (say 3/4 of it's normal travel) and drag the casing with it, damaged the carrier and still have enough spring energy to force the remnant casing back into the chamber in it's ragged form to "squeeze" it back into the chamber without ejection?

If the rifle cannot fire without being fully locked up...that primer was cleanly hit and detonated by the firing pin (as opposed to wicked - like a slam fire), could say...if the powder was too slow or fast in burning...have created too much pressure and residual burning time to cause the damage witnessed.

The picture shows the casing was ribboned open and that can only happen outside of the confines of the chamber. To have that happen, by default, the gas pressure in the port may have been sufficient to move the bolt out of battery while the powder was still burning. In this instance, the barrel would still be pressurized (as a result of the overload) and the bullet not yet ejected, the pressure would then find the weakest point....the casing, and blow wide open. With a normal load, the pressure would be dropping quickly, but with an overload...or incorrect powder...it would keep burning until depleted.
 
Secondly, there is the issue of how the casing, in the neck and shoulder area, managed to fold and wrap into itself as shown on the picture.
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The picture showing the case partially extracted was AFTER the OP had already started to pry it out of the chamber, so likely, it split and was mangled further whilst it was being removed.

With an AR or XCR, if you had the hammer ride the pin back and slam-fire it, the bolt would be locked when the pin hit the primer, and while you would get a big surprise, the gun would remain intact.

If the case was only on it's second firing, then I would be more inclined to believe that maybe the wrong powder somehow was introduced, but that is pure speculation as I don't know the OPs reloading habits. It could just be a case that was drawn incorrectly in the manufacturing process and failed much earlier than normal.

As far as how it blew out, it seems to have blown out towards the extractor recess (following path of least resistance).

My 223 (bolt) split a few casing necks open too.
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Split necks or case heads? Splitting a neck isn't usually that exciting. A head letting go, often more so. Also, a bolt gun is less likely to have as bad damage being that the bolt stays locked until you unlock it. With a gas operated gun, there only needs to be enough gas down the tube to unlock the bolt for things to get exciting.
 
*MALICE* said:
Sorry Savage, still not possible with an XCR or AR15. The firing pin won't be able to reach the bolt face unless it's locked (as previously stated many times). The barrel doesn't/can't unlock due to pressure alone, only once the bullet passes the gas port and siphons gas back to hit the carrier. The carrier moving rearwards turns the bolt, unlocking it. If you removed the carrier and just used the bolt to lock the round in place, and hit the firing pin, the bolt would stay locked.



Don't know about the M1 or M305.
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I am glad to hear that the RA XCR is so well built that it defies logic as to how this occurred . I highly doubt the carrier is the culprit as other have suggested as it does not rely on a rear locking lug like the Fn FAL ,FN 49 or the SVT 40 to lock the bolt into battery. That leaves every one to believe to believe that it was his reloading practices that caused the issue I am sure the OP is glad to hear that
 
I would be more inclined to believe that the rifle fired out of battery, most likely the firing pin was stuck in the out position. When the round meets resistance in the chamber it goes off prior to locking up. I had this happen to me on a Johnson 30-06 and the rifle came apart in my hands. Rigrat
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Your statement contradicts the evidence. You say you had a rifle fire out of battery and the rifle came apart in your hands. You believe that the OP's XCR also fired out of better yet the damage to the XCR is not even close to having come apart in the firer's hands. Thus by your own logic the OP's XCR didn't fire out of battery.


In the event of a catastrophic case failure with the breech locked, the high pressure gas will escape. A blown out magazine, and blown away extractor are to be expected. Receiver damage will depend on how the gas vents off.
Once the case fails, pressure drops to zero, essentially instantly.
It is odd that there was still sufficient gas port pressure to unlock the action, assuming that when the smoke cleared the action had unlocked and was opened, and that the damaged bolt carrier was able to effect unlocking.
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This is not necessarily true. I had a case failure when testing an AR with a wildcat cartridge. The pressure ruptured the case at the extractor cutout, damaging the extractor quite badly. The bullet went down the bore no problem even though a lot of the pressure came out of the ejection port. In my case the action didn't cycle because the extractor jammed against the side of the barrel extension. A ruptured case does not vent all of its pressure out the back of the case. I guess we could think of it as a recoiless rifle. The expansion of the propellant gas pushes in all directions.
 
We'll probably never know what happened. Lots of opinions here, I know mine, the back of the case was mangled because I pulled it out slightly with needle nose, then used a ram rod to knock out the rest of the case from the muzzle end.

I can tell you i have been loading for 3 yrs now I DON'T CRIMP .223, and this was my first issue, so after all is said I have a new Bolt and carrier on route thanks to Wolverine , approx $300+ to get to my door.

That first round I fire is gonna be a nerve racking experience.
 
The important thing was that you were not hurt in the incident. The important lesson for us reloaders, even if unrelated to the cause of the failure, is to always be attentive to our task.

As shooters, an important takeaway in this thread is to ensure the maintenance on our firearm is complete and thorough.

:D Happy and safe shooting all! :D
 
I can tell you i have been loading for 3 yrs now I DON'T CRIMP .223, and this was my first issue,
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That could have been your issue. If the bullet got set back in the case too far upon chambering it could have increased the pressure enough to make bad things happen quickly. I don't crimp for my bolt guns but always do for auto loaders just in case.
 
Unless loading 223 for my single shot T/C Contender carbine I crimp my 223's with a Lee Factory crimp die they are inexpensive and easy to use.
 
cyclic said:
We'll probably never know what happened. Lots of opinions here, I know mine, the back of the case was mangled because I pulled it out slightly with needle nose, then used a ram rod to knock out the rest of the case from the muzzle end.

I can tell you i have been loading for 3 yrs now I DON'T CRIMP .223, and this was my first issue, so after all is said I have a new Bolt and carrier on route thanks to Wolverine , approx $300+ to get to my door.

That first round I fire is gonna be a nerve racking experience.
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You should read the section about reloading for both AR15 and M14 in Sierra's reloading manual.
The 3 key points about millitary ammo are:
  1. heavy tough brass cases
  2. crimped primer
  3. cannelured bullet

You can't crimp a primer but might want to use high quality brass and cannelured bullets when reloading for a semi.
Also consider using Sierra's AR15 specific load data.
http://accurateshooter.net/Downloads/sierra223ar.pdf

Alex
 
cyclic said:
We'll probably never know what happened. Lots of opinions here, I know mine, the back of the case was mangled because I pulled it out slightly with needle nose, then used a ram rod to knock out the rest of the case from the muzzle end.

I can tell you i have been loading for 3 yrs now I DON'T CRIMP .223, and this was my first issue, so after all is said I have a new Bolt and carrier on route thanks to Wolverine , approx $300+ to get to my door.

That first round I fire is gonna be a nerve racking experience.
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There it is. You probably did have an over pressure event. I'd be willing to bet that your rifle stripped a cartridge from the magazine, and while the cartridge was being pushed up into the chamber, the bullet was pushed back into the neck of the cartridge. While it hasn't been made explicitly clear, you indicate that the kaboom happened after you pulled the trigger. (This rules out slam firing out of battery). So, you load a round with the bullet pushed way back in the neck of the cartridge and the pressure spikes to a higher level than the case can handle, but not high enough to blow the barrel. The end result is that the excess rearward force combined with the supercharged cycling action of the firearm brutalize the bolt face, and smash up the extractor while directing the bulk of the force out the paths of least resistance, the port door and down through the magwell. I've had something similar happen in an AR15. This is why crimping in semi autos is not something to be shrugged off.

However, I also think the idea of having some slop in between the bolt and cahmber may have had a minor role to play in this. Perhaps this looseness allowed the bolt to extract a little quicker than under design conditions, and this is what allowed the brass to deform like it did (out of battery like), where if the kaboom had been contained only in the throat of the barrel, then the brass wouldn't have been able to banana split like it did.

Out of curiousity, do you still have some of these reloads left? If so, you should put them in a kinetic bullet puller and see how easily they pop out compared to your other reloads or a commerical load. I bet you'll be surprised at the complete lack of force holding those non-crimped rounds in place.
 
cyclic said:
I DON'T CRIMP .223
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Me neither, but I crimp everything that goes in the chamber without my hand pushing it in.

Not doing so is asking for trouble IMO. Have you ever drop a round on the ground that is not crimp ? doesn't take much to move the bullet further in. Imagine what the ramp of a auto loader can do.
 
Bullet puller takes 3-4 hard wacks to get the bullet out. They do not come out easy which is why i don't turn my crimp down on my 650, i can even tap the bullet in using a light tap it doesn't move. My crimp die is backed out but maybe it still applies a slight crimp.
 
3-4 whacks isn't much. Did you compare with any crimped rounds? Most of my lightly crimped rounds take a minimum of 6. If there's a really good crimp into the cannelure, it'll take closer to 10 whacks, which is why I ended up getting a collet style bullet puller.

It's possible that the round that blew in your gun had a slightly shorter neck, and wasn't affected by the bullet seating die. This left the bullet held in the neck extra loose. When that round got rammed up the feed ramp (face first) bad things happened.

It only takes one!
 
I have a hard time believing that not having crimped his bullets was the cause of this failure Man that has got be the weakest explanation of this incident .I agree with Suptin I too have fired about 4-5 thousand rounds thru my AR's using reloaded non crimped ammunition and yes I have had bullets move back into the case because of using only a neck crimp . And yes I loaded the back into the mag and nothing happened when I fired them .I was using 55 gr FMJ bullets from Speer and Sierra at the time and no they did not have a canilure on them . So can any one tell me why and how a bullet that is set back into the case can cause a overpressure issue using a 62 gr projectile ????
 
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