need advice - AR15 Kaboom

[darkgael]

I wish that I did not have to write this....but soemthing went wrong and I do not know what. I have been handloading for decades with out ever a problem. I have loaded many thousands of rounds for my Colt HBar. Never a problem....until yesterday.
I was set up to shoot prone with 50 rounds that I had just loaded. I use only two loads for this gun: 77 grain Sierras atop 24 grains of Re15 or 69 grain Sierras atop 24.2 grains of Accurate 2460. The brass is new factory primed Winchester .223 Rem.
The cartridges used yesterday were the 69s. I checked the load weight about ten times during the powder drop. I examined the charged cases with a flashlight before seating the bullets. Cartridges were all loaded to 2.26" OAL.
I loaded a magazine and fired three shots. No problem. three shots - three holes in the target.
When I fired the fourth, there was a kaboom....the magazine was blown out of the magazine well and was destroyed. The fifth cartridge was on the mat. I was not hurt at all. The bolt (see the picture) is frozen in place. The bolt release lever was broken and could not be found (see the picture).

What I do not know is why this happened. Did I miss an overloaded cartridge? When i got home, I weighed the remaining cartridges. The weight spanned 188.6 grains to 192.4 grains. I took the ten heaviest and pulled the bullets and weighed the powder charge - all were 24.0 to 24,2 (Max is 24.7).
When i looked at the frozen bolt, I could see that it was frozen at about halfway to full engagement.
Any thoughts will be much appreciated.
Suggestions about how to free the bolt?

 

[hagar]

I'm not saying you have the same problem, but I had a Kaboom with my NM AR a couple of years ago. All of a sudden my reloads would not chamber, so I switched to a factory load, and first shot I had a kaboom. My theory is that a piece of brass or debris got stuck in the chamber and caused a barely out of battery condition. I got mine open by jumping off a bench at the shooting range and banging the buttstock as hard as I could into the dirt. Did destroy the magazine and sheared a lug off my bolt, otherwise rifle was unharmed.

Your loads sound safe to me.

 

[Skans]

My guess would be the round was slightly out of battery. Hard to say without seeing the shell. Could be that the primer wasn't fully seated, brass was out of spec. I'm not thinking that it was a double charge - if this were the case, the action would have been properly locked up and I'd expect to possibly see some barrel damage.

Oh, BTW, it looks like you might possibly have a crack in your upper receiver (lower right on the ejection port) - hard to tell from the pictures, but definitely check it out.

 

[mulespurs]

Maybe

When you get it apart I would check the fireing pin and make sure that it is not broken and jammed in the bolt face, causing it to fire out of battery.

 

[rickyrick]

Def looks like a crack in the reciever opposite the port.

Also with the BHO broken off, the upper "puffed" up and broke it off.

You need a new receiver I think.

 

[Jimro]

I agree, it was most likely an out of battery event. Could have been caused by a lot of things, but without knowing more there isn't much to go on for the exact cause. My guess is something mechanical rather than a reload mistake in this case.

Jimro

 

[HiBC]

First,I could be wrong with what I'm about to say.I'm not an expert.Second,I do not suggest people be careless.I'm not suggesting we can't get in trouble...
But here goes
I think the .223 /5.56 is a "balanced" case regarding case volume.Its not overbore.
Using powders of appropriate burn rate,its not unusual for case capacity to be the limiting factor for max powder charge.
I load 24.3 gr RE-15 behind 75 gr Hornady BTHP.I don't load 2460.
Generally,I think you might be able to stuff enough powder in a case to loosen,or even open a primer pocket.You might be able to extrude a primer till it blows.
But in this cartridge,I don't focus my attention on an overcharge of powder when using powders like RE-15,Varget,4895, etc.if there is a kaboom.

I'm not suggesting your powder was the wrong powder,or contaminated powder,but,IMO,about the only way to seriously wreck an AR-15 due to powder charge is to use either a wrong powder,such as a shotgun or handgun powder,or at least to select a powder where the max load via pressure leaves some empty case volume,therefore room for a significant overcharge.

For most .223/5.56 loads( with heavier bullets,slower powder),if you charge 2 gr over max,the powder will be up in the case neck.

All that to tell you I'd focus elsewhere.

You said it was Winchester factory primed brass? I have no experience with it.Can't recall seeing it for sale.I did buy some primed Lake City once.

I wonder if this might be a sensitive primer/firing pin inertia thing?

 

[Skans]

If he used the wrong powder, wouldn't he have had a problem after firing the first or second round he reloaded? He had fired a number of reloaded rounds with no issue.

When I used to reload, I often used shells that were stretched, difficult to resize properly and needed a couple of hard wacks on the bolt handle to get the bolt to close. This was for a 22-250 bolt action rifle. None of my reloads would have ever fed properly in semi-auto (if they made a semi-auto 22-250). Having some experience with stretched-out bottle-neck cases, that's why my guess was improperly sized shell - just enough to keep the bolt from rotating all the way and closing properly.

 

[MarkCO]

I agree, it was most likely an out of battery event. Could have been caused by a lot of things, but without knowing more there isn't much to go on for the exact cause. My guess is something mechanical rather than a reload mistake in this case.

Concur. In 20 years of doing forensic analysis of gun failures, the rate has increased dramatically in the last few years, especially in AR15s. The most common issues are 300BO in a .223 chamber, pistol powder, deep seated round, out of battery.

 

[darkgael]

Handloads

Let me repeat a detail so as to keep the record straight:
These were handloads; they were not "reloads". This was all virgin brass from a factory case of 4700 pieces, primed and sized by Winchester.
I have used a couple of thousand of them so far. This has been the only problem. The propellant used was Accurate 2460 no doubt about that.

 

[AK103K]

My experience with Winchester primers in any of my AR's has not been good. Every one Ive shot them in has had 2-4 round bursts out of them at some point during the outing. Didnt occur every time I pulled the trigger, but it was a regular thing until I stopped using the Winchester primers.

I normally use CCI primers in my autos, and Ive never had the above issue with them.

 

[Jim Watson]

Beats me.
I was once present when not one but two ARs blew.
Guns assembled from the same brands of parts in the same shop, same source of ammo. Had been shooting XC all morning until kaBooms.

 

[MarkCO]

My experience with Winchester primers in any of my AR's has not been good. Every one Ive shot them in has had 2-4 round bursts out of them at some point during the outing. Didnt occur every time I pulled the trigger, but it was a regular thing until I stopped using the Winchester primers.

And likely when solidly benched.

Due to imbalanced system, likely just way too much gas. AR15s use floating firing pins and when the velocity of the carrier is too high, the dimple on the primer can become too much resulting in ignition. Better to solve the imbalance in the system than bandaid it with a marginally harder primer.

 

[AK103K]

And likely when solidly benched.

Due to imbalanced system, likely just way too much gas. AR15s use floating firing pins and when the velocity of the carrier is too high, the dimple on the primer can become too much resulting in ignition. Better to solve the imbalance in the system than bandaid it with a marginally harder primer.

I dont shoot off a bench, all field positions.

Ive used CCI primers in all my auto loaders (M1's, M1A's, AR's) since the late 80's and never had any kind of issue with them. Back during the last "shortage", I ran short, and the Winchesters were all that was available. Had the above issue from the first mag. CCI loaded rounds have never done it.

If its an imbalance in the system, then its across the board, Colt, S&W, Armalite, PSA, etc, 20", 16", and 10.5". Funny its only the Winchesters that have the problem.

 

[Txhillbilly]

I've never had any issues using Winchester small rifle primers in any AR-15 rifle,and I shoot thousands of them every year. I sense a little brand snobbing going on here!

 

[AK103K]

No brand snobbing here. I use a lot of Winchester in my pistols reloads when I come across them on sale as well as CCI, Federal, and Remington.

I did have a bit of trouble with the Remington pistol primers recently though. Great price, $20/1000, but a lot of misfires.

Rifle wise, I dont normally use anything but CCI in my autos. That comes from shooting a lot of high power and DCM shoots with M1's/M1A's. I used to use Federals prior to that, but after having a catastrophic slam fire in my one M1 in a match, I started looking differently at how I reloaded for them, and what I used with them.

 

[Sarge]

It's been a while since I reloaded much .223 (for bolt actions and a Mini 14) but I'll echo everything HIBC said about case capacity. I mostly used H4895 and I couldn't have squeezed a 15% overload in there to save my life.

 

[FrankenMauser]

My guess would be an out of battery discharge.

You'll know more once you manage to get it apart to investigate further.
Be sure to do your best not to damage whatever may be left of the cartridge in the chamber.


If you release both pins, you may be able to wiggle and slide the upper off the lower receiver.
If not, then a brass drift and a hammer could be enlisted.
I, however, would prefer removing the butt stock and receiver extension (buffer tube) to gain access to the rear -- along with providing a little more slop that might let the upper come off the lower.

 

[stagpanther]

I ran the numbers on your loads--they appear to be above SAAMI specs in ignition pressure yields--24.7 2460 possibly way above--especially if it was a compressed load and something may have caused further compression. My vote is an out of battery ignition combined with a very hot load ignition. It could have possibly have been much worse--so don't feel bad. Glad you were unhurt.

 

[Sevens]

I have only two AR's, a Rock River that I bought years back and a budget build with PSA upper that I recently put together. I have no passion for them, they are to me like polymer striker fired handguns-- excellent tools that fill a role, I will happily use them for that role but get all of my passion and excitement and love for shooting elsewhere. While at the same time, I absolutely understand how & why so many love them, and I take no issue with that.

Here is what I do honestly take issue with:

How can anyone sign off on this design that has the damn firing pin kissing every single primer, absolutely every single time this rifle properly chambers a round?

-YES- I am sure that AR nuts who have burned many passionate hours discussing and arguing their favorite thing has probably run in to an old stick in the mud like me and dismissed the concern in a surgical fashion but I simply don't get it. I think it is absolute lunacy that this design has the firing pin kissing every primer and dimpling every primer.

Can anyone respectfully outline some manner of an answer that might make me change my mind? Is there something that I have missed or simply cannot understand? It REALLY seems like most of the possible answers to the OP's catastrophic event revolves around a possible or even likely OOB firing and one poster makes a very valid case for overgassing simply exacerbating what I believe to be an inherent design flaw.

Help?