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Old January 19, 2013, 10:28 PM   #1
NATE40
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Blown up ar15 help

I was shooting a buddies reloads and got a Real hot load and it blew up the upper and split the bolt carrier. Real bad time to get rebuild parts I know!
after stripping the parts to salvage I think the barrel is ok but just the barrel I was able to unscrew it from where it screws into the piece that has the lugs that piece is cracked and will not unscrew from the from what is left of the upper even with a vice and barrel nut tool. All the barrels I can find seem to have this end lug attached, The rifle was a m4 16 inch I have purchased a stripped upper and wondered if I can get this part and what the name of it is. I would just buy a complete upper to replace it but I cannot find one in stock in these WORRY days. Any help or guidance will be appreciated
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Old January 19, 2013, 10:37 PM   #2
a7mmnut
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You'll at least need a barrel extension, maybe more---from where, I just don't know....

http://www.midwayusa.com/find?sortby...mensionid=9672

-7-
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Old January 19, 2013, 10:51 PM   #3
NATE40
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fantastic and thanks for letting me know the name of the part!
I know i need quite a few other parts BCG ect. but if I can just round them up-lol I put one on backorder with midway and they should be in soon thanks again
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Old January 20, 2013, 01:04 PM   #4
243winxb
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AR15 Parts List link

Complete parts list/names with photos > http://www.midwayusa.com/General.mvc...chematics~AR15
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Old January 20, 2013, 01:39 PM   #5
Hawg Haggen
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One reason why I wont shoot someone else's reloads and wont let anyone else shoot mine.
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Old January 20, 2013, 01:43 PM   #6
James K
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+1 on that, Hawg!

I shoot only my own reloads. That way if anything goes wrong, I know the name of the SOB who did it and can hit him upside the head.

Jim
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Old January 20, 2013, 01:48 PM   #7
g.willikers
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So, did you beat him about the head and shoulders with what was left of your rifle?
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Old January 20, 2013, 03:49 PM   #8
DnPRK
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It will be virtually impossible to find a barrel extension that matches the one which split. The new barrel extension will have to be headspaced and pinned. Then the front sight base will have to be removed and a new gas port will have to be drilled. Lastly, the front sight base will have to be re-attached. It takes GO/NO GO gauges and precision fitting to do all that.

The bottom line is the "cheap route" will probably cost as much as buying a new complete barrel assembly.
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Old January 22, 2013, 07:19 PM   #9
tobnpr
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It will be virtually impossible to find a barrel extension that matches the one which split. The new barrel extension will have to be headspaced and pinned. Then the front sight base will have to be removed and a new gas port will have to be drilled. Lastly, the front sight base will have to be re-attached. It takes GO/NO GO gauges and precision fitting to do all that.

The bottom line is the "cheap route" will probably cost as much as buying a new complete barrel assembly.
^^^THIS.

You're in Gunsmith territory when doing/replacing a barrel extension.
Leave it alone...or you may end up with another blown-up rifle...or worse.

There's a reason AR barrels come from the factory with the barrel extensions already attached- because the headspace has been set within specs.

Get a new barrel...
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Old January 22, 2013, 09:27 PM   #10
USMC EOD
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I guess guns do have more enemies than just rust and politicians.
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Old January 23, 2013, 05:56 AM   #11
HiBC
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One more thing.

If your buddy was using a powder appropriate for the 5.56,like,any powder in the loading manual,and if that powder was not contaminated with handgun powder in the powder measure or something...

The 5.56/.223 does not have enough case capacity to put enough powder in to blow up the gun.

You can overload,open up the primer pocket,blow the primer,but that won't make the gun come unglued to the degree you experienced.

What may be more likely,bang,bang,bangclick,no bang! Hmmmm,must not have fed a round (wrong) Pull back the op rod,try again..KABOOM!

If you do not put powder in a round,the primer drives the bullet into the barrel,but it does not kick or make noise.When you put the next round in,the barrel is plugged by a bullet.That will make your gun come unglued.

I have heard of uncrimped bullets,or insufficient neck tension bullets,being driven back into the case during feeding causing extra high pressure,and maybe a blowup,but I'm not too sure about that.


Lesson!!Unless someone is really shooting at you,if the gun does not go bang when it should go bang,(handguns,too)STOP!

Clear the gun,MAKE SURE THE CHAMBER IS EMPTY!

Push the takedown pin,hinge it open,pull the bcg,and see if the hole goes all the way through the barrel.(Looking in the muzzle has you standing there with the gun pointed at your head.Bad form.If you open it up and look through from the breech,you look like you know what you are doing)

And,yeah,the idea of refitting a barrel extension is bad.

Assembling an upper requires some tools,some skills,and an understanding of what you are doing.Pick an upper assembly,get it on order,and be patient.

Last edited by HiBC; January 23, 2013 at 06:02 AM.
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Old January 23, 2013, 02:26 PM   #12
Rainbow Demon
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A blow up that severe may have bulged the chamber, so if you could remove the busted extension you should do a chamber cast and check to be sure the barrel shank is still within the proper dimensions and not distorted.

Probably best to spring for a new barrel with extension, then keep the old barrel for a future project.
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Old January 23, 2013, 06:43 PM   #13
neal95
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I'm with HIbC. The few ARs I have seen that blew out an upper were all caused by squib rounds.
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Old January 23, 2013, 08:13 PM   #14
tobnpr
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Or guys forgetting that they have their .223 upper on and load in a .300...
Or so I've heard...
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Old January 24, 2013, 05:50 AM   #15
HiBC
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I cannot say I know what happened,a squib is one possibility.I would expect you would find a ring in the barrel if it was a squib load.

Another possibility would be a slam fire.

A good primer to use is the CCI Mil-Spec.It is designed for the AR's needs.These days,folks are desperate for any primer.Some are a bit too sensitive.He may have loaded high primers,not fully seated.You may have some crud in your bolt that stuck a firing pin forward.
A slam fire can occur as the bolt is fully forward,but the bolt carrier and cam have not rotated the bolt to locked.

It is important to try to solve the mystery of root cause,and correct your process.To do less is to invite a repeat.

You may stop shooting your buddy;s reloads...good plan,but if he is standing next to you when his rifle blows up,.....It still stops being funny

Scrap the original bolt.If the receiver extension cracked,I would not trust the bolt.I would at least get a new cam pin.Agreed,if the receiver ext cracked,the barrel may have expanded.

It doesn't take a special person to build a complete upper,but it does take competence.OP,no disrespect to you at all,but reading your post,you aren't ready to be a builder.Learn more first.

Keep it safe!!Good luck.
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Old February 2, 2013, 12:57 AM   #16
silverbullet
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Malfunction

Probably not the right thread but I have never had this conversation before although I think about it a lot. Being in the prototype design industry, I am fully aware of the lack of strength in stainless steel. There are many types and some better than others but as a comparison, if you were bolting steel beams together you would not use stainless. The grade 8 bolts normally used would be your choice. Guess what, if you were to use stainless steel you would be using about a grade 2 strength. Im sure none of the parts in the rifle in question were stainless but this is something we need to think about and take a look at. Im not sure about stress fracture characteristics of steel vs stainless but they must be quite different from each other based upon the classification of grade strengths of bolts. Now, even if we dont experience the catastrophic results mentioned above, what about accuracy. How can the stainless grooves hold up like steel. Answer is they cannot. So where are we headed with all this stainless hardware? I only have one firearm that is stainless, a Ruger .45 LC.
There was a time when some firearms made of alloys other than pure steel were lined with a steel insert inside the barrel. It is sure something to think about down the road folks.
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Old February 4, 2013, 10:25 PM   #17
chris in va
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Quote:
You can overload,open up the primer pocket,blow the primer,but that won't make the gun come unglued to the degree you experienced..
You're forgetting a case head blowout.
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Old February 5, 2013, 05:11 AM   #18
HiBC
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chris,do you mean a case head separation due to brass thinning,or a pressure induced failure of sound brass?
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Old February 5, 2013, 07:50 AM   #19
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If I missed it, please forgive me. But it sounds like this could have been a "top fire". This is more often than not a reloader's error and it doesn't happen very often.
You're still looking at replacing the barrel, bolt, upper receiver and the rest.
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Old February 6, 2013, 02:03 PM   #20
AR15barrels
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Quote:
after stripping the parts to salvage I think the barrel is ok but just the barrel I was able to unscrew it from where it screws into the piece that has the lugs that piece is cracked and will not unscrew from the from what is left of the upper even with a vice and barrel nut tool. All the barrels I can find seem to have this end lug attached,
You generally can NOT replace a barrel extension as no two barrel extensions time up to the same spot on the barrel.
Also, I would worry about other damage on the barrel.
Just wait for the current parts shortage to clear, them get a new barrel.
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