AR Ka-boom 300 BO style (not a castboolit)

[JonB_in_Glencoe]

edited: this was not my gun....or anyone I know personally, this was a fella on a facebook reloading group.

Posted today on a FB reloading group

Hi guys, I went out shooting with some friends today and had a great time... until this happened. I had a case head failure and it took out my bolt. Nobody was hurt thankfully but I'm trying to figure out what happened. I've heard it's impossible for an ar to fire without the bolt locked in but that feels like what happened. I've loaded around 700 rounds for this rifle but only the last couple hundred with this recipe.
Ar15 .300 blackout Hornady 150 sp 16.2 gr Winchester 296


after some folks asked some questions, more info came out

yeah, It's a pretty hot load. Hornady shows it at max but that's with a magnum primer. I was using cci small rifle but not magnum. I think that usually equates to about a half grain reduction.


all the brass was 556 lake city 2012 headstamp.
Anything's possible but very difficult with my setup. I use a hornady lnl ap. It uses a case activated powder measure so if it gets powder it's pretty much always right there. Once in a while a tenth off. Double charge would spill powder everywhere.


https://scontent-sjc2-1.xx.fbcdn.net/v/t1.0-9/14199636_10210771700593349_2645783494405577199_n.j pg?oh=8c5d8d342c476142283e156f1c2a3bbe&oe=58800E59

https://scontent-sjc2-1.xx.fbcdn.net/v/t1.0-9/14199495_10210771700793354_7615885543812559068_n.j pg?oh=69d18efae30f5c8382dce2ff63f3ff17&oe=5851BC56


https://scontent-sjc2-1.xx.fbcdn.net/v/t1.0-9/14202684_10210771700993359_2048247742209774555_n.j pg?oh=0f010680ec6155dab591b387e363d60d&oe=587E365C

[Lead Fred]

One toke over the line

[Tackleberry41]

Guess he found out it doesn't take much when you operate that close to the edge. So its a max charge and the measure can be a 1/10 off, not a big deal. Some just have to go max charge with everything. Never seen a rule where just substituting a standard primer equaled a half grain reduction.

300BO seems to be one that people mess up alot. Know people that have them. One continued to use reloads that were blowing primers out and down into the receiver stopping the gun. He was just gonna blow em off. And continues to let the same guy keep loading for him as its just easier than doing it himself. Same guy who was supposedly sizing .311 down to fit in a 300BO, vs I dont know just buying the proper bullets.

And somebody else got 2 bullets stuck in a brand new barrel. The load data was a bit questionable. As it was trailboss mixed with something slower burning, guess there was some theory behind it. Then offered me some of his 223 subsonic reloads to try, um yea no thanks.

[Hamish]

Max charge of 296 plus possibly throwing heavy PLUS military head stamp brass,,,,,,,,,plus using sized down jacketed bullets,,,,,(possible spring back?)

Dude was certainly blessed.

[popper]

Case neck looks funny too. Possible setback & compressed load? AR slam-fire? I like that bullet in my BO. CCI SRP too. My guess he lost more than just the BCG. What FB loading site?

[JonB_in_Glencoe]

Hamish, I assume tackleberry's fella who was sizing down 311 bullets (probably CB) to fit 300BO, is a different fella than the fella I posted about.
==========

I posted the OP, cause I thought it was a chance that it was a S.E.E.. Possibly caused by wrong primer/poor ignition. But after more, continue discussion on FB, it seems more likely to be a firing out-of-battery issue, as the owner, when asked, claims all the locking lugs on the bolt look good, and the lugs inside the barrel extension 'feel' good.

[JonB_in_Glencoe]

Case neck looks funny too. Possible setback & compressed load? AR slam-fire? I like that bullet in my BO. CCI SRP too. My guess he lost more than just the BCG. What FB loading site?
PM sent

[osteodoc08]

Perhaps this is what they call.....a clue.

Some people just shouldn't reload.

i reload my 110gr Zmax with 19.9gr 296 as that is what has given me best accuracy. Some references list 20gr as max, others have listed higher. My brass looks good and there are no pressure signs I'm seeing.

[LynC2]

A too thick neck might be a possible factor also. I load for a 7.62x40 WT and have to watch for necks that are too thick with some reformed cases. That issue certainly would raise pressures off the chart.

[Preacher Jim]

Jon that fallacy that they can't fire unlocked should read highly unlikely but I had a 223 do that not to the catastrophic result you had but enough to shake my faith in absolutes case ruptured on down side gas went in the mag

[JonB_in_Glencoe]

Jon that fallacy that they can't fire unlocked should read highly unlikely but I had a 223 do that not to the catastrophic result you had but enough to shake my faith in absolutes case ruptured on down side gas went in the mag
Oh, this wasn't mine or anyone I know personally, it was just a fella on facebook. I posted to start a conversation.

[Char-Gar]

Move along here, nothing to see. Just another irresponsible handloader should not be allow around a loading press.

[NavyVet1959]

I've had ONE slam-fire with an AR and it was inside my reloading "shack". I still have the hole in the carpet and dimple in the concrete to prove it. No damage to the brass though.

[bruce drake]

Hey! I use the same load in 296 my 30-223Rem with those Z-Max bullets! Its a good load. I could possibly add a grain more powder but why when its effective and accurate.

[Yodogsandman]

High primer? Dirty bolt? Crudded up chamber? Soft primer? Minimal sizing? Thick neck?

[popper]

Yup, any of those + dirty FP, lots of reasons. Yes, slam fire of 308W near max load with cast boolit will take out a BIG chunk of concrete. Shoulder just a tad too long. Yes, it disintegrated but the GC didn't. Case gauge is your buddy.

[JonB_in_Glencoe]

one of the photos of the disassembled BCG

the poster states...

The firing pin does have a little weird corrosion on it. That's not carbon.

https://scontent-sjc2-1.xx.fbcdn.net/v/t1.0-9/14212059_10210779102698397_1643276147211316350_n.j pg?oh=8da20887cf07d3e58bf485bf58348746&oe=5880180B

[Hamish]

Ah, now we're getting somewhere,,,,,,,

[Tackleberry41]

Hamish, I assume tackleberry's fella who was sizing down 311 bullets (probably CB) to fit 300BO, is a different fella than the fella I posted about.
==========

I posted the OP, cause I thought it was a chance that it was a S.E.E.. Possibly caused by wrong primer/poor ignition. But after more, continue discussion on FB, it seems more likely to be a firing out-of-battery issue, as the owner, when asked, claims all the locking lugs on the bolt look good, and the lugs inside the barrel extension 'feel' good.

No this guy wasnt sizing cast .311 down to .308. He was sizing jacketed .311 AK bullets to .308. Told him to stop, use a bullet puller, but he was determined to burn thru what he had 'for the brass'. He works in a gun shop.

My friend wont use a cast bullet in ANYTHING, even tho the 300BO really seems to like cast. He gave me a box of the Lee 230gr, the same guy had cast them. Not one was actually .308 much less .309. It was free lead to toss in the pot.

[mcdaniel.mac]

I saw an OOB once on an AR. The dingleberry decided that the floating firing pin scared him, so he added a spring to keep it from dimpling primers during cycling, then added a stronger hammer spring to fix the light strikes. Eventually the spring broke and jammed the firing pin forward resulting in a quick 3-round burst that ended with an OOB and a bullet stuck in the bore.

He's the sort of fella who sports a scar on his palm, courtesy of his own handgun. Let's just say he's slightly more diligent about clearing the chamber these days.

[popper]

Spring on the Fp was a fix for AKs going auto. Looks like the poster has a couple short fingers from before! Light oil on the BCG only. Good reason to use US on it. Cotter pin is heck to get back in.

[NavyVet1959]

Spring on the Fp was a fix for AKs going auto. Looks like the poster has a couple short fingers from before! Light oil on the BCG only. Good reason to use US on it. Cotter pin is heck to get back in.

I see fingernails, so maybe that is just the camera angle.

[Remiel]

I have not had a slam fire with the wifes ar(mine is still Being built). But it looks like he never kept up on PM, my wife goes 150 to 250rds before either I or she cleans it, and since 90% of her ammo is my reloads she has not had an issue. However I dont load anywhere near max and use my lyman case gauge constantly. I do the same with my M1. I have had one slam fire in my SKS but it was due to a 200+ run of tulammo then 20 of federal, but a quick cleaning got her back up in running for the rest of the range day

[Kestrel4k]

+1 on the poster who mentioned thick case necks - I can certainly see how that could happen when starting with LC military brass.
I sure wouldn't want to run max loads of W296 with that situation.

[tomme boy]

An AR CANNOT fire out of battery. He screwed up and does not want to admit it

[35remington]

Yes......as soon as it is admitted a handload is used everyone immediately becomes infallible cartridge assemblers and enormously unlikely or impossible events are advanced to explain wrecked guns. Of course it couldn't be the guy making the ammo. Let's claim it was caused by something less likely than a lightning strike to explain it, shall we?

Of course no one ever screws up reloading so we must invoke the impossible or enormously improbable to explain it.

As has been said many times before.....if a handload was involved, very safe money says the handload caused it.

[popper]

An AR CANNOT fire out of battery Total BS. Please QUIT passing that BS around!!!!

[BK7saum]

Just for my own edification, what condition would allow an AR to fire out of battery. The firing pin cannot reach the bolt face until the lugs have rotated into battery by the cam pin.

[mcdaniel.mac]

Just for my own edification, what condition would allow an AR to fire out of battery. The firing pin cannot reach the bolt face until the lugs have rotated into battery by the cam pin.
Debris on bolt face (rare), damaged or missing cam pin, bad feed issue resulting in bolt hitting primer, high primers, and as I mentioned goofball modifications to the bolt. Oh, and excess heat if you're running one of those stupid bump fire stocks and you have a cookoff.

If it's clean (no metal shavings), hasn't been inexpertly modified, and you didn't oopsie your ammo, and you haven't tried to make a rifle into a belt-fed MG, then it is nearly impossible.

[popper]

FP protrusion thru the bolt is limited by the bolt length. The cam pin ONLY captures the FP with the edge of the FP hole. Stack up prod. tolerances and BANG. If you consider the FP of ~ 100gr., thats 100 ft-# of energy. No I haven't weighed the FP but you get the idea. It CAN happen.
edit: Apologies if I came across too harsh but the comment is like saying no gun can go off unless the trigger is deliberately pulled or you measure never throws light or heavy. It is a hazardous statement. Always assume Murphy is around.

[Japlmg]

Sure looks like an out of battery discharge to me.
And yes, an AR platform can fire out of battery.
It rarely happens, but is does happen.
Gregg

[tomme boy]

An AR CANNOT fire out of battery Total BS. Please QUIT passing that BS around!!!!The ONLY way it can is if the FP is stuck out. The BS is people that think it can. It was a case head failure or he loaded it too hot. plain and simple. No one wants to admit they screwed up. But this person did. The only way it COULD have is if something was broken or jammed. Then the cause was NOT a out of battery firing it was the broken part. The AR CANNOT fire out of battery if everything is working as designed

Show me ONE case of proven AR firing out of battery

[NavyVet1959]

So, *if* everything is working the way it is supposed to, an AR cannot fire out of battery.

Thus, if it fired out of battery, then everything was *not* working the way it was supposed to.

Caca pasa...

I know for a fact that a slam fire can occur, because I've had it happen to me. Most likely, it was a case of a proud primer and using Federal pistol primers.

[jhalcott]

I had a navy .45 auto empty the mag when i dropped the slide. The slide was closed and hammer down on anempty chamber. I have beetold by "experts" that it can NOThappen. But it did!

[FLYCUTTER]

I would like to know how the 45 could fire on a empty chamber ? Or are you saying all the rounds fired and the slide closed with the hammer down ? The slide always stays open on the last shot with the hammer back.

[Geezer in NH]

So, *if* everything is working the way it is supposed to, an AR cannot fire out of battery.

Thus, if it fired out of battery, then everything was *not* working the way it was supposed to.

Caca pasa...

I know for a fact that a slam fire can occur, because I've had it happen to me. Most likely, it was a case of a proud primer and using Federal pistol primers.Note you caused it.

[NavyVet1959]

Note you caused it.

Well, that goes back to the "*if* everything is working the way it is supposed to"... Obviously, *I* was not working the way I was supposed to... :)

[koehlerrk]

Mmm, humans, the weak link in any chain...

[gpidaho]

When I talk with some of the folks out at the range it just amazes me that there aren't more eyes and fingers lost than there are. Gp Oh yah, I post one the facebook page some. Some pretty good folks there but a lot of New B's

[mikeingeorgia]

It always concerns me when people on some pages brag about how they assembled hundreds of rounds in just 1 day, because that sounds like quite a bit to keep tabs on to me. Of course, it could just be me going slower, but I've never made that many at one time.

[NavyVet1959]

It always concerns me when people on some pages brag about how they assembled hundreds of rounds in just 1 day, because that sounds like quite a bit to keep tabs on to me. Of course, it could just be me going slower, but I've never made that many at one time.

Depends upon what type of press you have. With a progressive press, it's a lot easier to do than with a single stage press.

[JonB_in_Glencoe]

It always concerns me when people on some pages brag about how they assembled hundreds of rounds in just 1 day, because that sounds like quite a bit to keep tabs on to me. Of course, it could just be me going slower, but I've never made that many at one time.


Depends upon what type of press you have. With a progressive press, it's a lot easier to do than with a single stage press.

While I rarely do a large batch of rifle ammo (typically 50 or 100), this summer I did 1k of 223/556...and let me tell you, the case prep alone (all brass was 2x LC) took many days with my non-automated tools/techniques. Of course, I don't sit down and build ammo for 8 to 10 hours at a time...when the case prep was done, I think I spend a few hours each of the following three days to assemble that batch in my Lee turret press.

Myself, I am not a fan of the progressive. I bought a new Lee pro-1000 and mounted it to the bench. I sat there and tried to get familiar with it, by cycling it (dry runs), and I just wasn't confortable with having more than one function happening at the sametime. I decided I like the turret, where only one thing happens for every stroke of the handle. So I sold the Pro-1000...having never put any powder or primers through it.

[NavyVet1959]

Myself, I am not a fan of the progressive. I bought a new Lee pro-1000 and mounted it to the bench. I sat there and tried to get familiar with it, by cycling it (dry runs), and I just wasn't confortable with having more than one function happening at the sametime. I decided I like the turret, where only one thing happens for every stroke of the handle. So I sold the Pro-1000...having never put any powder or primers through it.

Just from a design standpoint, I'm not particularly a fan of the Lee presses with the pull chains. As such, my Lee is just the 4-hole turret press. My Dillon is a 450 and does not have the auto primer or auto powder measure. Although I like the design of the actuator rods on the Dillon better, for the amount of ammo that I load, I am satisfied with having to manually cycle the primer arm and powder measure during each pull of the press arm.

Mine operates similar to this one:

https://www.youtube.com/watch?v=4FSYDxkSHcQ

I also like to separate seating of the bullet and crimping of the brass into two different stages, so a 4-hole press is the minimum for me for either a turret or progressive.

[jimb16]

I shoot large quantities of .30 carbine and .30-06. And I love my Dillon 550Bs. While I do my case prep on a single stage, the loading gets done on the Dillons. The only things you need to watch out got is running out of primers and powder. If you have and use the low primer and low powder alarms, you can really crank out large numbers of rounds in a short time. I find that the loads are very consistent and more than accurate enough for my needs. BTW, I have 2 550s. One is set up for small primers and the other for large primers. It saves a lot of time when switching calibers if you don't need to switch primer feeds as well as dies and shell plates. I also load quantities of .45 auto, 9mm, .38 spec, .223 and .380. For smaller runs, I still use an old Pacific single stage. Works for me.....

[farmbif]

a short stroke /part way pull of the lever on the hornady ap can put -1 plus some more powder- load into a shell. the powder measuring drum doesn't tilt all the way and shell plate doesn't advance. I could see that may be possible, plus no telling who made the bolt and how hot it was when it happened, Is it possible to cook off a primer before bolt is in battery? There are millions more reloading "experts" than there were just 10years ago and more millions of ignorant shooters who think they are gunsmiths because they watched how to assemble an ar on you tube and put one together for themselves. I quit trying to go to public range when i'm in florida on weekends since there are so many gun experts that go to range to see who can pull the trigger the fastest with their home built ar.
Guy was lucky, a few more grains of 296 and there could have been bolt chips flying through the upper

[NavyVet1959]

millions of ignorant shooters who think they are gunsmiths because they watched how to assemble an ar on you tube and put one together for themselves.

The vast majority of the gunsmiths that I see these day at the stores are not what we saw back in the '60s and '70s. These days, the "gunsmiths" are just installing factory or aftermarket parts and there is no fitting required. A lot of it is due to the popularity of the ARs and the modular nature of them. Many "gunsmiths" don't even own a lathe or milling machine.

[Tar Heel]

I hear about these events every day at work. With all the tekkies building their own guns, and with all the lack of knowledge about "details" like headspace, and with all the basement mega-handloaders, it's a wonder why we don't have more injuries. I just shake my head and keep my yap shut. Darwin will win.