Sanity check me - 300 BO Kaboom from reload

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20X11
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Re: Sanity check me - 300 BO Kaboom from reload

Post by 20X11 » Sat Dec 12, 2020 1:04 pm

[quote=BJK post_id=1006500 time=1607693932 user_id=74666
Frankly the potential is there for a double charge can happen no matter how I load. If I load on the progressive press if something happens in the load process I can get a double charge, but generally I know that's a possibility and address it. If I'm on the single stage press I get around that by using a loading block and drop all the powder charges one right after the other while they're in the loading block. Then I eyeball every case before seating the bullet.
[/quote]

Yep...I agree...on a single stage operation, I always drop all powder charges into the cases in a loading block without any other distractions or processes happening, then visually inspect.
On a progressive, I always use a powder check die (I prefer Dillon with an audible alarm). Some folks like a powder check lock-out die, but to me it is too disruptive to the process.

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Dr.Phil
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Re: Sanity check me - 300 BO Kaboom from reload

Post by Dr.Phil » Mon Dec 14, 2020 10:09 am

Sound more like Secondary Explosion Effect (SEE).
http://reloadammo.com/liteload.htm
AA#9 sub loads have a super low case fill and if the charge was even lighter, SEE makes sense.

That being said, with how quickly pressures can spike with AA#9 in 300 BLK, what could normally be a small error in charge weight could be catastrophic in 300 BLK.
SEE is a bit of a controversial topic and this powder does have a great deal of potential to grenade a firearm.

AA#9 is a very scary powder in 300 BLK.
With sub loads, the powder density is super low and with supers, pressure spikes VERY quickly.
I used it quite a bit in 2010 when doing development, but have since retired it.

Glad you are safe and thank you for sharing so others can learn as well...
"Don't tell fish stories where the people know you; but particularly,
don't tell them where they know the fish."
--Mark Twain

JStarX7
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Re: Sanity check me - 300 BO Kaboom from reload

Post by JStarX7 » Tue Dec 22, 2020 2:30 pm

Update:

Had to take a dremel to the AR upper assembly. I pulled the handguard and SiCO flash hider. Gas block is pretty much un-removeable. I managed to get one set screw out, the other is welded in. I torched it, soaked it, lubed it, you name it. It broke 2 allen wenches. Wound up cutting the gas tube. Viced the upper, but could not get the barrel nut off. Could not lever out the bolt carrier.

Started cutting the upper off. Got it really loose, but because the charging handle is still on the gas key, the upper won't come off because the bolt won't come out. Cut part of the chamber so I could get to the bolt teeth. Will not turn. Wound up cutting the entire chamber in half and was then able to snap the whole thing off. That part of the chamber was STILL not able to be removed from the bolt. I had to cut that part in two to get it off so I could remove the bolt carrier from the upper. It looks like the chamber was expanded a bit, which locked in the bolt and the barrel nut.

So, the case was cut in two when I cut the chamber. But the head had a missing chunk that was blown off where the extractor sits. The extractor was blown in half and that was where all the extra pressure must have gone out the ejection port and magazine well. The case was molded to the bolt face. I mean, I had to pry it off and you can see the ejector was pushed in by the case and the brass flowed into the shape of the ejector. The primer was flat against the bolt face. The bolt carrier has two splits on the bottom. The gas key was fine, and thankfully my expensive charging handle was burnt but otherwise intact. I was also able to salvage the backup sight and the firing pin.

TexTenn59
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Re: Sanity check me - 300 BO Kaboom from reload

Post by TexTenn59 » Wed Dec 23, 2020 12:21 am

If powder volume is too low, it can lead to a detonation. All powder burns instantly. Saw results of a M1 Garand destroyed at CMP match in Talladega. Shooter was using a low volume powder and it detonated.

Blackout!
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Re: Sanity check me - 300 BO Kaboom from reload

Post by Blackout! » Sun Dec 27, 2020 2:06 pm

A double charge on a subsonic load is nearly impossible without noticing it. Even on a Dillon, loading fast, you are bound to see it, unless you are completely careless about it.

Using 9 grains or so a double chg = 18 grains, which is about 1/4” to 1/8” from the top, or completely full, depending on powder. You would have noticed it for sure.

An incorrect load is more likely than a double chg. Maybe a 50% chg or even 150%. Stranger things happen every day.

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dellet
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Re: Sanity check me - 300 BO Kaboom from reload

Post by dellet » Sun Dec 27, 2020 2:33 pm

Anybody saying a double charge can’t be done is Foolish or ignorant. Until you intentionally double charge and check, you won’t know.

That load, depending on seating depth, is no more than about 55% density.

The traditional thoughts on SEE don’t really hold up because #9 is often loaded as low as 40% density.

You’re left with the two strongest possibilities of

#1 double charge

#2 induced SEE. I say induced because what happens is with a poor crimp the bullet jumps too far into the bore before the powder fully ignites and become more of a blockage than projectile. The blockage causes the kaboom.
300 Blackout, not just for sub-sonics.

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Re: Sanity check me - 300 BO Kaboom from reload

Post by Blackout! » Sun Dec 27, 2020 5:59 pm

dellet wrote:
Sun Dec 27, 2020 2:33 pm
Anybody saying a double charge can’t be done is Foolish or ignorant. Until you intentionally double charge and check, you won’t know.
Double charging is sort of like popping off to someone’s post before actually reading it. It can be done, but you would have to be a fool or ignorant to do it.

You should read more than the first 10 words before replying.

Like I said, it can be done, but if you were paying attention, you would certainly notice it. Would be easier to miss on a Dillon, but if you are not checking every load while messing with subs, you are going too fast.

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dellet
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Re: Sanity check me - 300 BO Kaboom from reload

Post by dellet » Sun Dec 27, 2020 9:22 pm

Blackout! wrote:
Sun Dec 27, 2020 5:59 pm
dellet wrote:
Sun Dec 27, 2020 2:33 pm
Anybody saying a double charge can’t be done is Foolish or ignorant. Until you intentionally double charge and check, you won’t know.
Double charging is sort of like popping off to someone’s post before actually reading it. It can be done, but you would have to be a fool or ignorant to do it.

You should read more than the first 10 words before replying.

Like I said, it can be done, but if you were paying attention, you would certainly notice it. Would be easier to miss on a Dillon, but if you are not checking every load while messing with subs, you are going too fast.
I didn’t quote you before, because I wasn’t necessarily speaking to you directly. There are more posts than yours implying a double charge would easily be noticeable.

For argument let’s look at your post.
Blackout! wrote:
Sun Dec 27, 2020 2:06 pm
A double charge on a subsonic load is nearly impossible without noticing it. Even on a Dillon, loading fast, you are bound to see it, unless you are completely careless about it.

Using 9 grains or so a double chg = 18 grains, which is about 1/4” to 1/8” from the top, or completely full, depending on powder. You would have noticed it for sure.

An incorrect load is more likely than a double chg. Maybe a 50% chg or even 150%. Stranger things happen every day.
The OP had a load of 8.3 grains #9, a double charge would be 16.6 grains, and the powder level of that charge would be closer to 1/2” down In the case or 1/4” below the neck. Had you read the original post you might have known that and not implied he could not possibly have missed a double charge without being completely careless.

He used a 220 grain cast round nose, its likely less 1.300” long, it that is true, then the bullet loaded to 2.170” never touched the powder on a double charge.

That’s the difference between popping off in a thread you know nothing about and actually having experience with what he did. Mistakes happen it’s part of the game. Limiting those mistakes, sharing what went wrong helps others.
300 Blackout, not just for sub-sonics.

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Re: Sanity check me - 300 BO Kaboom from reload

Post by Blackout! » Mon Dec 28, 2020 4:53 am

There is no need in taking that tone with anyone, calling people ignorant fools here. Take it down a notch pal we are all just guessing, you included.

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Re: Sanity check me - 300 BO Kaboom from reload

Post by Regaj » Mon Dec 28, 2020 7:48 am

There are a few things in this world that don't suffer fools. Running a chain saw. Working a tractor. Piloting a motorcycle at speed. Shooting a gun. I'd include loading ammunition in that group of things that can hurt you in an instant if you're careless.

I believe Dellet was using the royal "we" when he suggested one might be foolish or ignorant. Much as it might pain us, that is a cloak we've all worn a time or two. And most of us will again.

Not calling it when we see it would be the real tragedy, though. That makes us partner to whatever bad thing is coming.

Mama always said "if you don't have something nice to say, don't say anything at all." Bless her heart. Turned out she was right about most things. She was wrong about that, though.

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