Blew up a gun Thursday... now tell me WHY?

[Larry Gibson]

Felix I understand, pressure-time curve, but until someone shows me a real cast bullet SEE, which I've not yet seen, the SEE thing with cast is only theory and discussion about it. I'm using some relatively small charges of 860 in some of my loads, but with a filler to decrease case capacity, and generally, but not always, with a kicker to speed up the burn rate. Put enough fire in the back end of it and it burns about 4350 speed, which it should as surplus 4350, first called 4350 Data, then 4831, was also originally a 20mm cannon powder, and these 800 something powders have to burn at a similar rate to get similar ballistics in said cannon fodder. Thing is these powders were meant to be ignited with a primer a lot bigger than any LRM primer.

Of the 2 SEEs with cast bullets that I am aware of both used a heavy for caliber bullet. It take more psi and a longer time to get those moving. Also I am not awayre of a single SEE, even those with jacketed bullets, where the bullet did not "get going" and exited the barrel. Problem was the psi reached catastrophic levels and the case gave way before the bullet could exit and relieve the spi fast enough.

In madsenshooter's example he is negating the SEE conditions with the use of a smaller charge of slow burning powder with the filler. Thus the force of the primer alone would probably not blow through the powder and filler and move the bullet into the throat. Also the smaller amount of powder doesn't have the total burn surface nor total volume of gas capability. The generally with a "kicker" ensures the slower powder is ignited correctly. Thus maddsenshooter is using such in a correct and safe manner.

Many "cannon powders" are considerably slower burning than 4831. It appears the powder jonk used is quite slower. Also slow ball powders have a heavy deterant coating (it's how the burn rate is controlled) and are much harder to ignite than an extruded powder like 4831. It appear that the powder jonk intended to use is such. However, please note that 4831 also has it's own extensive SEE history. Yes cannon shells do have a larger and more powerful primer. They also have a much larger case with a much larger volume of powder and a much heavier bullet with a lot more neck tension and a heavy crimp; all of which provide for consistent ignition and keep the bullet in the case until the powder is burning efficiently.

Just because a powder works in one or several applications does not mean it will work in the same manner in all applications. This is exactly why I told SciFiJim; "There are many, many different combinations cartridge/powder/bullet and what is potentially dangerous in one instance can very well be perfectly safe in another. It takes experience to use slow burning powders where no data exists and one must use judgement."

Larry Gibson

[felix]

Well, Quickload says ? grains of BlueDot and a 60 grain boolit in a bone-stock 221 Fireball is about, (wait for it) . . . . . ???,??? psi. Some one please fill in the question marks! ... felix

[daschnoz]

the above is one heck of a testament to the rifle. It is a great wonder that it didn't "catastrophically accelerate in all directions".

Did quickload give an estimation of the boolit's velocity?

18" - 2841
20" - 2890
22" - 2933
24" - 2970

[303Guy]

Quickload's pressure prediction did not take into account the release of pressure when the action gave way. It probably assumed an expansion as the boolit moved down the bore though.

[tonyjones]

The following information is provided for context and in the event that anyone finds it interesting. wideners.com has the statement regarding WC 867:"Use AA 8700 data for other (other than .50 BMG) cartridges". From the Accurate Smokeless Powders Reloading Guide Number Two I found the following:
p289 8x57mm Mauser 24" barrel 170 (L) FNGC RCBS
8700 49.1 1581 54.5 1797 24,100 psi 2.710" COL Compressed
p5 8700 "Interestingly, it performs well in a large variety of cartridges for cast bullet loads. Use of a magnum primer is recommended for best results".

Regards,

Tony

[Mk42gunner]

jonk, thanks for the update.

After reading this thread, I am kind of glad that my loading/ casting bench is small; thus making me take the powder measure off the stand when I get done loading.

Robert

[303Guy]

jonk's thread in invaluable to the observant re-loader (those who observe and learn). While I regret he had the misfortune, I am grateful he posted the warning for us all to learn from. I will be imposing stricter safety procedures on myself! Not so long ago before I tightened up my act after reading other posters experiences, I was doing things that could so easily have lead to a mishap. My tightening included procedures to prevent the very thing that happened to jonk, but now I realise there are still loopholes in my act!

So, here's to jonk!

[MtGun44]

Glad you are OK.

In flying we say a good landing is any landing where you can walk away. A great landing is
where you can use the airplane over again.

So a good load, but not a great load. Hope you can smile at that!

So a Mauser can "withstand" 134,000 psi - and mostly protect the shooter. Awesome.

Again, VERY glad you are OK, sorry for the wallet impact, too and also glad to understand
the actual cause.

Bill

[BAGTIC]

You did not mention bullet make of style but Quickload shows a pressure 137-154 THOUSAND psi, depending on bullet.

If you did accidentally get 47 gr of 2400 in that case there is no reason to look for SEE or any other esoteric explanations. The pressure would have been 3-4 times normal.

[Milanodan]

Just OOC, but what kind of psi would be generated with Bullseye?

[Shiloh]

I'm pleased you are not hurt.
This is a great thread and I thank you for posting it. It is bookmarked for future reference.
A lesser rifle could have cause severe injury to you. It must have caused shock when you think about what could have been. I got a shudder just thinking about it.

Shiloh

[olafhardt]

I have had arguments with some of the responders that they did not know as much about what goes on in the bore as they think they do. Listening to all these theories of SEE and such reinforces my beliefs. I will stick with my Lee dippers.

[morgans]

Sorry to hear this happened, and Mainly know your ok.

Intresting reading, good post Except the fact your guns busted up

Just chiming in I've only seen this happen in person once, I'm 50 years old shorthly and when I was 12 on rifle team, a school bud did not have safty glass's on, Anyways he paid dearly Powder burn , but was ok after words,Only reason for mention , is he used factory Ammo. I've seen photos over the years and it was from "hot Loads" Human error.
Other wise I find all this reading again very intresting, Glad your OK and thanks for post.
Have a good day.

[Char-Gar]

I never, never leave powder in the measure, and just threw some 3031 that appeared by magic in my measure on the flowers. Those darn Brujas are at it again!

[missionary5155]

Good morning
I am happy you can read this and was kind enough to post this to remind us to stick to safe procedures. The Mauser action when rightly executed has probably saved more lives than we can imagine.
Mike in Peru

[175lt2]

I have seen enough speculation on why this happened in this thread . All I know is I won't be trying any mystery surplus powder any time soon,,, It's only a few bucks cheaper than new powder, not worth a blown up gun or worse yet getting Dead.....

[FLINTNFIRE]

Have used both 867 and 872 in 7mm magnums and 264 win. and was very satisfied , hate to see bashing of surplus powders as these are very economical and it is always refreshing to see someone step and say hey I made a mistake , I had a ex brother in law blow up a customised 1917 in 264 mag. by picking up a 308 win. and driving the bullet halfway down the bore before all heck cut loose.

[hicard]

Approx. 111,000 PSI and 2891 fps with that load you blew your gun with Jonk.

[MtGun44]

175lt2 -

You missed the point - he knows EXACTLY why he blew up the gun, zero mystery.

All of the SEE and stuff is NOT about this particular case.

He loaded the wrong powder - a fast one and the computer prediction software says
he was around twice the pressure of a proof load.

Bill

[1Shirt]

Yep, as MT Gun44 says, wrong powder factor. I blew up a rifle that I think might have been for the same cause. When I change powders, I always empty the hopper, and throw the handle a couple of times just to be on the sure side. Have doubts that a few grains of unique or bullseye and a full charge of 4064 or 4831 would be anything but cortustamuss to weapon, and propably the trigger puller.
1Shirt!