AR blowup

[243winxb]

Brass had to be fired many times to get that long.

KABOOM
I inspected a Win M70 30-06, that when fired, it locked up the bolt & split the wood stock. Range brass was never checked for length.

I DID NOT CHECK CASE LENGTH. Some were nearly 1.780"

If not long brass, then a squib left a bullet in the barrel. Firing another round, takes the gun apart. Can be seen on Youtube.

 

[rwj]

I hope that the OP has determined the cause and takes the appropriate remedial actions. That said, how close to being completely chambered does the cartridge have to be for an AR fire control system to allow the hammer to fall?

 

[akajun]

Something I picked up over the years loading for .223 service rifle competitions and loading for a junior team
335 powder can get touchy real quick especially with temp, I loaded a batch up for practice with a pound and ruined a bolt from all the pierced primers , would only happen in summer. After that I stuck with slower powders like varget, rl15, 8208, and TAC.
Mixing brass is not an issue, at least for short line, most of our junior brass was donated , range pickup and as long as it was all prepped the same and carefully never had a problem
Trim every reload to 1.750-.1.755. Yes a long case will pinch the bullet in the chamber. I’ve shot lots of high x cleans with “ mixmaster” brass.
Use magnum primers or military primers, they have thicker cups, less popped primers
Make sure your gun has a wylde, nato, or cle chamber
Make sure your full length sizing with a good quality die. You should be getting an average of .003-5 shoulder setback . One thing people miss is that dies will wear out near the base so check its reducing the area about 3/4 of the way down a little as well, at least .001.
Don’t use a small base die.

after all that , I’d think yes it’s possible that way over length cases with high charges of 335 can cause case head seperations

 

[Kracken McGraw]

335 powder can get touchy real quick especially with temp, I loaded a batch up for practice with a pound and ruined a bolt from all the pierced primers , would only happen in summer.

I was curious if Ramshot Exterminator powder acts like the 335 powder in this regard.

 

[barefooter56]

5.56x45 NATO load used in a 223 REM chambered AR?

 

[DGP4]

5.56x45 NATO load used in a 223 REM chambered AR?

I was thinking along these lines as well.

 

[ebb]

You mentioned reloading experts looking at the loaded ammo. If the "experts " had your over length ammo in hand and didn't put calipers to the cases and measure case OAL, then they are not experts. Jlenko nailed it one page 1, the third reply to this 6 page thread. I have had an issue with long brass myself, my mentor told me to be careful but I was not. The Ruger rifle suffered no damage, but the case hit the bolt so hard there was no brand stamp on the case head left.

 

[jelenko]

Soft steel will deform if the bolt isn't run forward EASY.

Ah. Thanks!

So, the disclaimer if for people who would just release the bolt and let it slam shut.

So, if you ease the bolt forward it will work perfectly fine.

 

[akajun]

Ah. Thanks!

So, the disclaimer if for people who would just release the bolt and let it slam shut.

So, if you ease the bolt forward it will work perfectly fine.

That’s the worst thing to do on an ar
If there’s any slop in the bolt , or in the hammer / bolt carrier safety clearance , you will get an out of battery shot
But more than likely just a bunch of misfires from the bolt not fully closed
Always release the bolt on an AR, or any semi auto, but make sure there’s a mag in it. I know a few people who didn’t and had slam fires with AR 15 and 10’s floating firing pin
The follower slows it down enough

 

[jelenko]

That’s the worst thing to do on an ar
If there’s any slop in the bolt , or in the hammer / bolt carrier safety clearance , you will get an out of battery shot
But more than likely just a bunch of misfires from the bolt not fully closed
Always release the bolt on an AR, or any semi auto, but make sure there’s a mag in it. I know a few people who didn’t and had slam fires with AR 15 and 10’s floating firing pin
The follower slows it down enough

But, we're talking about how to use the Sinclair chamber gauge not about firing the rifle.

 

[akajun]

But, we're talking about how to use the Sinclair chamber gauge not about firing the rifle.

Ah
lol missed that part

 

[karrarararararar]

I don't know about that.... I have some IMI 5.56 that has considerably less internal volume than the same period (late 90s) Winchester brass.

IMI is not Lake City (or Winchester) which is what the military uses. It is well documented that Lake City is on the higher end of capacity, Winchester too. Lapua has less. Here's one example from a video Johnny's Reloading Bench did years ago.

 

[CJ6]

Something I picked up over the years loading for .223 service rifle competitions and loading for a junior team
335 powder can get touchy real quick especially with temp, I loaded a batch up for practice with a pound and ruined a bolt from all the pierced primers , would only happen in summer. After that I stuck with slower powders like varget, rl15, 8208, and TAC.
Mixing brass is not an issue, at least for short line, most of our junior brass was donated , range pickup and as long as it was all prepped the same and carefully never had a problem
Trim every reload to 1.750-.1.755. Yes a long case will pinch the bullet in the chamber. I’ve shot lots of high x cleans with “ mixmaster” brass.
Use magnum primers or military primers, they have thicker cups, less popped primers
Make sure your gun has a wylde, nato, or cle chamber
Make sure your full length sizing with a good quality die. You should be getting an average of .003-5 shoulder setback . One thing people miss is that dies will wear out near the base so check its reducing the area about 3/4 of the way down a little as well, at least .001.
Don’t use a small base die.

after all that , I’d think yes it’s possible that way over length cases with high charges of 335 can cause case head seperations

IMI is not Lake City (or Winchester) which is what the military uses. It is well documented that Lake City is on the higher end of capacity, Winchester too. Lapua has less. Here's one example from a video Johnny's Reloading Bench did years ago.

IMI is the only military brass I have to go by. I don't have any LC brass.

 

[snert]

Oh, I learned many valuable reloading tidbits this mishap. I am also paying a LOT more attention to each and every detail, period. I mistakenly believed all was well, when I could have caught it had I been more vigilant. Again, I trusted somebody else's work, and he was getting on in years and missing things. My bad. I am a better reloader out of this for certain. Now I am no longer so confident, and more cautious.

My hero, mentor and good friend was long a reloader and a fine shot. About five years ago I sold a rifle to him (I was $$$ poor and in a bind and he bought it to help me). I sold him my rifle, scope, and all my brass.

He proceeeded to change the trigger, the rings and develop his own load. When I bought it back it wouldn't shoot for crap.

I changed everything back and had to toss 200 Lapua 22-250 brass becuase of clickers. Then I saw his data. He was 2 grains large on his powder charge. I know what he did...he changed powders, but in the process confused his old powder charge with the recommended new one. He is in his mid 80's, had some health issues, and had a shooting lay off in there too. He simply isn't as sharp as he once was.

I love him to death, but am grateful he is entering his willing retirement from loading age....

I have to keep this in mind becasue I too am getting a bit fuzzier...not remembering so I have to write it all down, every time. Recently I loaded some 20 VT and am seeing a little dimple of ejector mark on the rim face. Yup..hot. Backing down. More care being taken

 

[Doom]

The type of damage the OP describes in similar in nature to what happens when a 300 blackout round is chambered and fired in a 223 barrel. Based on that and the case OAL I believe the case locked the bullet in the case. This was not a powder charge event @ 25 gr regardless of the case manufacturer.

 

[searcher]

I wonder if something besides the firing pin struck the primer.

An AR-15 firing pin cannot reach the primer until the bolt fully cams into the locked position, and I am pretty sure it is the same on an AR-10.

I have seen a few semi-auto rifles destroyed at the range when the bolt was released and a round was already in the chamber. One of them (was) a beautiful Browning 7 mm Mag BAR

 

[writerman]

Someone wanted to know if the 'blow up' was in target group size, or actual rifle. I'd say.....actual rifle. Blew out the magazine, destroyed it, couldn't find the extractor pin, split the extractor in half, bulged the lower, cracked it, cracked the upper. Split the barrel extenstion in half. Believe it or not, I learned a whole lot out of this experience. Small wounds from shrapnel, I'm fine.

 

[kevinbritvec]

I loaded 250 rounds of 55 grain Sierra FMJ spire point, with 23.5 grains of H335. OAL 2.200. Case length 1.760. I had a rifle blow up. Then I took apart some rounds and they were all within spec. Went to the range. Another rifle blew up. I took apart all 250 rounds and they were from 23.4-25 grains, all within published specs. All the cases were from 1.755 to 1.765. All the OAL's were close to 2.200, some shorter, some longer, but none off by more than a couple of thousandths. All within published specs. Went to a reloading expert who took apart and measured everything and could not come up with an answer. We even tested the powder. Some were military brass. All were lightly crimped. I would like to know of anyone who has had a similar experience, and who actually discovered what happened? Not interested in more bleating about 'double charges' it wasn't, or 'you did something wrong, it's all your fault' that doesn't help. What would help would be actual answers and actual personal experiences. Thanks.

How on earth are you getting powder charge variations +/- 1.6 grains using a ball powder?

Ball powders can be hand thrown with less than .1 grain variation round to round.

Your COAL" variation tells me you don't trim brass. I trim every case, every time it gets resized. Using a quality power trimmer, it takes less time to trim than it takes to measure each case. I suggest buying Giraud's trimmer that can be chucked in a drill and use it. Best $100 you will ever spend.

I use the actual bullet manufacturer's data when referencing manuals. Just because a bullet weighs 55 grains, does not mean it will be able to use other bullet data weighing the same. Bullet construction has a say in pressures being created.

IMO, you had powder charges outside of your intended goal, had two cases that actually pinched the bullet hard when chambered because they were too long, or your powder was polluted with a mix that wasn't H335.

It is easy to put the wrong powder in a container if you have more than one powder on the bench at any given time. A lot of powders are so similar in appearance you can't tell them apart simply by looking at them. Some people don't thoroughly empty their powder measure after every reloading session. If you left even a small amount of pistol powder in the hopper, your rifle will blow up when fired.

I would consider the entire batch suspect and tear them down and start over again. Count your blessing, some people have been seriously injured from reloading accidents.

 

[RED DIRT]

Here you go:
https://www.brownells.com/reloading...s/sinclair-chamber-length-gage/?sku=749000811

I`m guessing the OP`s gun`s were AR type gas operated rifle?

Read the last sentence within the picture. These gauges aren`t to be used in "semi-automatic" (Hmmmm..?) Am i missing something here? I didn`t see where the OP said it was a bolt gun, or semi-auto. If semi-auto, i think i would find another way to measure the chamber before buying one of these gauges. Yes/No ?





EDIT: @jelenko
I see you responded in knowing this now. I`ll leave it posted for others to see so that they can clearly see that these gauges are not meant for semi-autos.

 

[Rocketvapor]

Title is
AR BLOWUP