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I blew up my rifle!

Southernspeed

Southernspeed

Sergeant of the Hide
Full Member
Minuteman
Sep 11, 2018
178
158
After 40 years of reloading, I think I finally screwed up ..... I think.

I was working up a new subsonic load (300 blackout) for one of my rifles, just a plain Jane AR15 that I've had a few years. I saw a load on Ultimate Reloader on YT and thought I'd give it a try. Berry's 220 gn plated bullets over 9, 9.5 and 10gn of H110, COAL 2.230", loaded 10 of each.
First shot .... BOOM! Thought I'd lost my hand! I rarely shoot with my left hand on the magazine but this time .... yep. It blew the mag to pieces.
You can see in the photos that the case head is still in the bolt face (bolt and upper are toast), the rest of the casing is in the chamber. It sent the bullet and thankfully didn't blow up my suppressor.
I have no idea what happened. My first thought was a double charge, still leaning towards that. I pulled all the others I loaded today and they were all on the money so my powder measure was working fine. I've mic'd a random selection of the bullets, they all measure .308-.3095 (is that acceptable??)
Would a bad case (head separation) be so catastrophic? It tore the bolt apart!
So clearly my upper and bolt are history, would you scrap the barrel too? The lower looks very slightly bulged at the mag housing and it broke the mag catch arm off but seeing as this component doesn't (normally) take any force, and you can by heavily skeletonized versions and polymer ones, I'm thinking I'll be ok to use it again, what do you guys think?
When I pulled the bullets I double charged one just to see if it was possible. It was, kind of. Two loads fit in but with a 220gn bullet it's a very compressed load and the round wouldn't stay at the set length, easing the bullet out a fair bit. It would still fit in the mag I think (didn't try) but I think it would have been noticeable in the box.
So, thoughts on what may have happened and thoughts on reusing the barrel and lower appreciated.
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Shooting with a dude last week him using an M1A.

He came by me with his broken case extractor and a piece of brass with its clean separated case.

I suggested he check his shoulder setback but he resisted and said they were light loads nothing to worry about.

I said he should bend a paper clip and look for imminent case head separation.

But he was only shooting light loads so it wasn't a problem.

It was probably the 4-5 reload.

Whatever.
 
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wvfarrier said:
Could have been an out of battery explosion. That listed load definitely would not have done that. I dont think a double charge would have . I load the 200 grain smk's VERY hot, actually close to your double charge and only get slight ejector marks.
Click to expand...
I can certainly see an out of battery explosion causing the mag to grenade, and even the case to separate but tearing the bolt apart?? Mind you, the bolt head was in the extension but not locked .... I don't know, it's weird.
 
I doubt out of battery, damage too severe. I suspect barrel obstruction. Cleaning patch left in bore or perhaps a bullet. I ejected a live round the other day and the bullet had caught the lands and remained in the barrel.
 
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buffalowinter said:
I doubt out of battery, damage too severe. I suspect barrel obstruction. Cleaning patch left in bore or perhaps a bullet. I ejected a live round the other day and the bullet had caught the lands and remained in the barrel.
Click to expand...
I ran a snake through it yesterday, then put the can on today to shoot it. Can was clean too 🤷‍♂️
 
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List of things that cross my mind:
1. Barrel Obstruction
2. Double Charge
3. Left over powder of a different type dispensed into the first round

I don't believe a case head separation of the normal type would be that catastrophic. This looks much more like extreme overpressure with the case head stuck in the bolt face like that. It is very difficult to get an AR to fire out of battery like that. Something would have to be out of spec pretty bad for that to happen.
 
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Mordamer said:
List of things that cross my mind:
1. Barrel Obstruction
2. Double Charge
3. Left over powder of a different type dispensed into the first round

I don't believe a case head separation of the normal type would be that catastrophic. This looks much more like extreme overpressure with the case head stuck in the bolt face like that. It is very difficult to get an AR to fire out of battery like that. Something would have to be out of spec pretty bad for that to happen.
Click to expand...
Definitely not No.1, possible No.2, got me thinking about No.3 although I know I actioned the drop mech several times after tipping out the powder, but it was Accurate No.9. If that was it, it was just coincidence that it was the first chambered round that blew, as that was obviously the last loaded in the mag although I didn't load them in any order (of all the 9gn loads) Rifle has worked fine for hundreds of rounds.
 
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I’m guessing maybe debris on the bolt face and it shoved the case too deep in the leade and squeezed the case mouth. Or the case was just too long.
 
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H110 really needs to be used with a case filling charge or a compressed charge.
10gr is a tiny amount in a case of that size and I could easily see it getting a double charge and going un-noticed.
I have seen a shit ton of warnings about less than case full charges of it over the years.
Strangely Hodgdon has a load listed with a 220gr bullet and shows 9.2 gr as a max load.
Nothing is mentioned about a filler.....but you'd be a fool not to use one.

Oh...wait....

Reloading Data Center

www.hodgdonreloading.com www.hodgdonreloading.com
 
I had an almost identical experience a couple of years ago with the exact same cartridge (300 BLK).

Ultimately I chalked mine up to the brass. I formed my own cases out of .223/5.56. Some of the case necks were too thick to allow the bolt to fully close.

It was undetectable before the bullet was seated, hence I have purchased a case gauge to make sure.
 
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pmclaine said:
Shooting with a dude last week him using an M1A. He came by me with his broken case extractor and a piece of brass with its clean separated case. I suggested he check his shoulder setback but he resisted and said they were light loads nothing to worry about.

I said he should bend a paper clip and look for imminent case head separation.

But he was only shooting light loads so it wasn't a problem.

It was probably the 4-5 reload.

Whatever.
Click to expand...
^^^^^^^^^^^^^^^^^^^
Don't rule this one out just yet. Double check your brass if you have several reloads on them. I witnessed exactly what pmclaine describes here earlier this summer during a high power match at a local range. The first thing he checked when he got the case removed from the chamber was wall thickness of what was left of the case closest to the base and determined that was the culprit. Fortunately for the guy it wasn't catastrophic.
 
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Southernspeed said:
I can certainly see an out of battery explosion causing the mag to grenade, and even the case to separate but tearing the bolt apart?? Mind you, the bolt head was in the extension but not locked .... I don't know, it's weird.
Click to expand...
My BCG looked almost identical to the pics in the OP... so yes.
 
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Mordamer said:
Something would have to be out of spec pretty bad for that to happen.
Click to expand...
See my previous posts...I had an almost identical problem as the OP. My BCG was split just like his.

The gun in my case was totally 'in spec'. And I know for 100% that I did not double charge my case when it happened to me.

In my case--and what I suspect here as well-- is the brass itself had too thick of a neck. The bolt would go almost all the way closed, but not quite enough...In my case it definitely was an out of battery detonation. I would bet $$$ the exact same is true here.
 
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Regarding out of battery situation;
doesn’t the bolt carrier prevent the firing pin from reaching the primer unless the bolt carrier is far enough forward? And the bolt carrier can only be forward enough IF the bolt rotates and locks in?
So out of spec parts? Or broken cam pin?
Or something else.
 
Makinchips208 said:
Regarding out of battery situation;
doesn’t the bolt carrier prevent the firing pin from reaching the primer unless the bolt carrier is far enough forward? And the bolt carrier can only be forward enough IF the bolt rotates and locks in?
Click to expand...
The answer is no. "Far enough forward" yes. Completely, no. I am holding in my hand a brand new Radian BCG that has never been installed or fired. If you hold the firing pin in and push on the bolt, there is a slight amount of play that makes out of battery most definitely possible. It's not a matter of 'in spec'.

In general, what you said is correct. In concept. In reality on almost every BCG there will be a small, very small area where this is possible. Take any one of yours and test it yourself.

Another way to test is to push the bolt all the way in. Then push on the firing pin. There will be a small amount of space...a mm or two where the bolt moves. That little gray area is what makes out of battery possible when using bad brass for example.
 
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One image is the bolt fully closed all the way. The other image is when I push on the firing pin. The gap there is maybe 60-70/1000.

Anywhere in between there the firing pin can make contact with the primer.

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IMG_20231122_221010387.jpg
 
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Ah I see, on a couple of mine I checked it can technically be out of battery as far as the bolt carrier is concerned, but where the bolt begins to rotate to unlocked, there the firing pin can no longer protrude from the bolt. I’m not an armorer or educated on this so I must be misunderstanding the cycle or fitment or operations.
 
Makinchips208 said:
Ah I see, on a couple of mine I checked it can technically be out of battery as far as the bolt carrier is concerned, but where the bolt begins to rotate to unlocked, there the firing pin can no longer protrude from the bolt. I’m not an armorer or educated on this so I must be misunderstanding the cycle or fitment or operations.
Click to expand...
What happens, as was my case, when you have a bad piece of brass there is substantial drag when the round is being chambered. This not normal friction pushes the bolt to the rear, but as I show in my pictures, the firing pin protrudes enough to strike the firing pin in BOTH of those positions.

It can in essence pre-maturely rotate the bolt as well as the firing pin extends out enough to strike the primer anywhere in that 'tolerance' pictured.
 
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Makinchips208 said:
Ah I see, on a couple of mine I checked it can technically be out of battery as far as the bolt carrier is concerned, but where the bolt begins to rotate to unlocked, there the firing pin can no longer protrude from the bolt. I’m not an armorer or educated on this so I must be misunderstanding the cycle or fitment or operations.
Click to expand...
You're right. The only way the pin reaches when the bolt unlocks is if something is grossly out of spec or physically broken.

alamo5000 said:
What happens, as was my case, when you have a bad piece of brass there is substantial drag when the round is being chambered. This not normal friction pushes the bolt to the rear, but as I show in my pictures, the firing pin protrudes enough to strike the firing pin in BOTH of those positions.

It can in essence pre-maturely rotate the bolt as well as the firing pin extends out enough to strike the primer anywhere in that 'tolerance' pictured.
Click to expand...
Notice the bolt is still rotated in both your pictures meaning it's locked in place. Where the carrier is relative to the bolt doesn't matter. Bolt face stays in the same spot and locked. Any further back where the bolt unlocks, then the firing pin can't reach. Further back and the firing pin can't be hit by the hammer.
 
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Makinchips208 said:
Ah I see, on a couple of mine I checked it can technically be out of battery as far as the bolt carrier is concerned, but where the bolt begins to rotate to unlocked, there the firing pin can no longer protrude from the bolt. I’m not an armorer or educated on this so I must be misunderstanding the cycle or fitment or operations.
Click to expand...
In a normal situation the lugs lock up into the barrel extension via rotation. Not a lot of rotation, but enough rotation. When that rotation happens too early (because of bad brass hanging up in the chamber) it causes a problem. And as stated the firing pin protrudes enough to contact the primer in both positions in my pics.
 
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srt-4_uk said:
Notice the bolt is still rotated in both your pictures meaning it's locked in place. Where the carrier is relative to the bolt doesn't matter. Bolt face stays in the same spot and locked. Any further back where the bolt unlocks, then the firing pin can't reach. Further back and the firing pin can't be hit by the hammer.
Click to expand...
Maybe I am not quite following...but in my other posts it's not a single thing... with the bad brass it forces the bolt back into the carrier pre-maturely... so that's one problem...it will prevent proper lock up...and with that, in both of my pics the firing pin would hit the primer...if I pull the bolt out even a little bit from the one position, it will not make contact.

It's a combination of those two factors that make it possible.
 
alamo5000 said:
Maybe I am not quite following...but in my other posts it's not a single thing... with the bad brass it forces the bolt back into the carrier pre-maturely... so that's one problem...it will prevent proper lock up...and with that, in both of my pics the firing pin would hit the primer...if I pull the bolt out even a little bit from the one position, it will not make contact.

It's a combination of those two factors that make it possible.
Click to expand...
I don’t recall the other thread, was the bad brass due to case head separation?
 
Makinchips208 said:
I don’t recall the other thread, was the bad brass due to case head separation?
Click to expand...
I don't think I ever had a thread here. I am talking about my personal case from a couple of years ago.

By 'bad brass' I am specifically talking about something that is pretty much only applicable to 300 BLK, not necessarily a structurally broken case.

Specifically, I cut down brass on my own and formed it to 300 BLK. When doing this some brands of .223/5.56 brass will result in the neck thickness being too much. When you form the brass you cannot detect it (at least not very easily). However whenever you seat the bullet you have the bullet diameter + the neck wall thickness (x2) that will prevent it from seating in the chamber.

There are lists on the internet that name the 'bad brass' by name, so if you get any of that just use it for .223/5.56 or toss it. Just don't form it to 300 BLK.

The brass itself is not structurally bad. No. It just results in a round that dimensionally will not fit in many chambers.

You COULD turn the necks to solve the neck thickness issue, but really it's just as easy to either: Avoid those brands of cases; get a $20 case gauge; or a combination of the two. Or you could just buy factory formed 300 BLK brass from the get go.
 
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BCP said:
If it was in battery I bet you dun goofed and put 2x as much in a case.
Click to expand...
Not sure a double charge would fit in a 300BLK case with a 220 at that OAL. I can barely fit 20gr of H110 with a flat-base bullet like the Barnes or Hornady 110s for my supersonic loads at that length.

My suspicion would be OAL was off or something else caused the bolt to not go completely into battery.

edit: just saw the rest of the posts…or case separation. How many times has the brass been loaded? Annealed at all?
 
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