I was firing my AR and the bottom blew out of the mag.  Bullets, spring and follower went flying (downward).  I could not pull the charging handle back or get the rear pin out easily.  I finally got the rear pin out, and the upper would not tilt.  I removed the stock and tube and tapped (hard) the bolt forward so I could get the upper to tilt.  The bolt is stuck firmly in the upper.  With a fair amount of force, I can get the bolt about 3/4 inch to the rear, but not far enough to see the chamber.  I can see the star shape at the front of the bolt, but I can't tell if there's a bullet in the chamber.

I hope someone can give me some good advice and even tell me what I can expect to have to fix/replace.  Thanks.

you do not have a jam, you had an exploding case, ala, KABOOM, how loud was it?

bet you noticed a different sound level, ok, what make and model of gun, what chamber, 223, or 556, and what ammo were you using?
glad to hwear that you are still alive, and not damaged other than in the wallet

yep, sounds like a KB..

got pictures?

Brute,

DUDE !!! Your name sure does fit you.  Anyone that thinks a KB is a jam is one-hecka of Brute. [pound]  Hope you are ok.

What ammo was you using ?

I will assume it's a KB based on your input.  Thanks for the super fast replies!

The sound was a little different when it "blew", but I didn't think anything of it initially.  When the trigger didn't reset, I began examining the rifle.  Aside from the blown out mag, the rifle appears to be in pristine condition, at least externally.  I'm not sure wether it's .223 or 5.56.  It's a DPMS flattop upper with the M4 profile barrel.  I don't know if it's chromed or not.

I was originally using Winchester ammo in the white box.  It seemed to function fine, but the rangemaster made me stop using it due to the FMJ.  I went into their pro shop, and bought some Hornady ammo.  After closer inspection, it turns out that it's remanufactured ammo.  Grrr...  Serves me right.  All they had for .223 that I could shoot was some match ammo, russian ammo, and the Hornady remanu ammo that I chose.  I was just sighting it in, so I didn't really want to spend the money for the match ammo.

Since no damage is apparent, what do you think I might have to fix or replace?  I plan to take it to a gunsmith, but I look at this kind of thing like buying a car... the more info you have, the less you get bent over.

Thanks again for all your help!

They sell Russian ammo but ban Winchester white box from their range???  Arent both of them FMJ??

guestimate on parts to be replaced....

you could do this yourself

mag, duhhh

maybee an extractor, or ejector, could have messed up the charging handle, or the bolt body itself, you may need a gas tube, or gas rings, you will need to closely examine the bolt/carrier group, all parts, look for cracks in the cam pin area of the bolt and carrier, and replace the cam pin if it looks hammered, the firing pin may also have went south

if all looks well check and clean the bore, the chamber, and the barrel extension teeth for damage, use carb cleaner or some other aggressive type of solvent to remove all fouling, ect, you need to have it perfectly clean so you can see any deformaties

reassemble, and go through the first and second pages on this forum for troubleshooting, and function checks...

let us know how it goes... too bad you are not near me, i could fix it

I had this exact problem yesterday.  Now the bolt is shoved forward and will not loosen.  I have removed the upper receiver from the lower. Any suggestions on how to free up the bolt? sure would preciate it. BTW this is a bush master shorty .223

I was trying out my new BM MX-15 with S.S. 20" barrel after zeroing it, when the mag blew out the bottom after about the 5th round. The back of the shell casing was blown out. The casing also failed to eject. And was a lot louder report than the others. I cleared it with no problem. I removed the bolt carrier, disassembled it , cleaned , lubed and put it back in. Everything else looked fine. I tried another round and it failed to eject also. Ammo was 5.56 55 gr. fmj, but found out later it was remanufactered. What can I do now?

You should read technical note 49 at: http://www.armalite.com/.

Also take a look at "the dangers of cheap ammo" at: http://www.bushmaster.com/faqs/troubleshootingfaqs.asp#10

If this happened to me I would make damn sure the headspace was correct and that the chamber was not too large.  I would also closely examine the ammunition for dimensions and powder charge.  Inspect the cam pin, carrier, and extractor for any signs of cracks or other damage.  Sometimes the receiver get's bulged out when this happens.

[red]GET PICTURES[/red]please!

That's srcewed up.

I'd try to run a one piece rod [close to the diameter of the bore] down the bore and try to drive the bolt back.
It is going to take some force. You will have to hit your fine rifle firmly. After you're done and get your rifle apart, examine it closely.

Make who sold you the ammo pay for it.  Save the other rounds for forensic analsys.  Get a lawyer.

Yep, it was a case failure.  It vents a lot of pressure.  This is a classic AR blow.  The great thing is that the design is so well shielded that you didn't get hurt.

It was most likely the reloads.  The range probably won't stand behind it though.  Let us know if they don't so we can stay away.

If they refust to stand behind it, contact a lawyer.

File a suit in small claims court since they ordered you to stop using the winchester & you bought the kaBoom ammo from their shop.

You might be able to get a new rifle out of it.

Glock makes AR's? [BD]

Well, I finally manhandled the @#$%@^ thing enought that I got it apart.  I'm sure y'all that are more experienced than I am at this will find this a little elementary, but I will post it for the very few people that are even less experienced at this than I am.  The rim of the case blew outward and pushed the extractor outward.  This caused the extractor to push outward against the rear of the chamber preventing the bolt from cycling rearward.  To add insult to injury, a small brass fragment blew back in between the extractor and bolt and wedged it outward.  Anyway, I finally found a steel rod that would fit down the bore without too much clearance and I tapped it out from the inside.  The extractor is trashed, so it will need to be replaced.  I'm taking the rifle to a gunsmith that I trust to have him borescope the rifling and chamber.  I think the firing pin is bent, so I'll have that replaced.  I'll see how much of the bolt assembly is still in A+ condition, and replace the rest.  Thanks again for all the suggestions and help, and I will definately be pursuing this with the range.  If the range gives me any flak, I'll let you know who they are so you can avoid them in the future.

Don't forget to take pictures, pictures are worth a shit load if the judge has to decide the case.

That was, more or less what happened to me, I've had a KB from a slamfire (I mistaken some pistol small primer for small rifle, and they went into reloading press), during an extended string of fire, one round detonated from out-of battery, thanks god was the last one in the mag.

I've had a bulged and ruptured case and a blown off extractor, other than that, the gas went downward cracking the bolt carrier (see my thread about it) and dinging very slightly the magazine.

All the people who examined my ar told me that I've been extremely lucky that the receiver did'nt cracked.