300 RUM Kaboom

[redleg]

I once blew up an AR15 when I was sold W296 powder labelled as BLC2. The barrel was undamaged ( to the eye), and the receiver was in many pieces. The bolt was slightly damaged, the carrier shattered. This was not a slightly over pressure failure, and it sure reminds me of what I am seeing in the photos above.

 

[Hitzy]

Hitzy, the tensile strength (destruction) of the brass CHAMBERED case is determined by the next metal part to fail or the amount of space the case can grow.

Now that tensile strength may also illustrate its elastic limits. That makes sense to indicate why brass 'grows' during firing. Brass can't spring back.

If brass while chambered was able to 'explode' at 85,000PSI, I bet ALOT of shooters would no longer be with us.
Jerry

Proof loads are generally 25% more than the average pressure the gun is intended to have a steady diet of, 120,000PSI would damage a commercial hunting firearm considerably.
http://yarchive.net/gun/ammo/pressure_signs.html
http://www.findarticles.com/p/articles/mi_m0BQY/is_4_50/ai_113853252
http://www.thegunzone.com/30cal.html

#A proof load is about 75,000 psi. This is 25% more pressure than a
#safe max load. It will result in chamber i.d. growing by 25%, from
#0.00024" to 0.0003" - half a tenth of a thou, roughly.

The minimum European proof load for the 8x57 is 73,500 psi.

Chamber Pressures
.308 Winchester
MAP: 62,000 psi
MPSM: 66,000 psi
Minimum Proof Pressure: 83,000 psi
Maximum Proof Pressure: 89,000 psi

7.62 x 51mm NATO
Maximum: 50,000 psi

Proof pressure: 67,500 psi

 

[aacollectible]

Well, you guys may say that I'm out of whack, but I've also loaded 200 gr accubonds using RL25 powder in my 300 RUM. First shooting session went very well (no signs of pressure at all, excellent groups), the second time got a little scarry. I had one fired round that got a bit"sticky" in the chamber when extracting, then another round got really sticky (I literally had to pry on the bolt handle to open it). At this point, I stopped shooting the rest of my rounds :shock: (wasn't grouping as well as last time anyways). So I started using Retumbo, solved my problem.

I swear that RL25 is a "shifty powder" that I no longer trust. I am convinced that it is more sensitive to temperature then others as well. (shooting in hotter weather vs cooler weather).

call me crazy

 

[Mystic Precision]

You may want to follow to this forensic link. Should be a little bit more current and are done in accordance with SAAMI protocols. The good stuff is 2/3 of the way down the page.

http://www.firearmsid.com/Feature Articles/022001/HPWhite.htm

Proof is max 1.5 times the working pressure of the ammo.
The action will show no failure to function. So for most magnum rds, that would be around 96000psi

Excessive pressure testing which can lead to catastrophic failure is up to 2.5 times the working pressure. For magnum cartridges, the action should 'hold' 130,000psi give or take.

You can always check on the SAAMI site to verify more details on the procedure but I think this link is quite complete.

There is no way a slightly over loaded ammo can cause that type of failure due to excessive pressures. Primers would blow out and other such good stuff long before an action fails. Something really screwy happened all at once.

Jerry

 

[PerversPépère]

Looks like a goof substituting handgun powder for the correct one or a massive undercharge with a very slow powder leading to the rare but possible detonation phenomenon.
Hope the guy got away alive! :shock:
PP.

 

[Boomer]

I was just back at AR, and it looks as if the owner of the .300 RUM might of sanitized the remaining ammo. That would be unfortunate if it means that the reason for the failure is unattainable. Certainly a new rifle could be tested to failure with increased loads of Re-25, but I rather doubt that a heavy load of this powder was the sole reason behind this failure.

 

[alberta tactical rifle]

More speculation, I have seen several actions KBed before, and have doubts that this was an overload, I would suggest most likely an underload and probably detonation. Many reloaders do not think that too little powder is actually in some cases worse than too much.
To split an action like that is some feat, to have a straight split along the top of the action, I think is also a sign of a possible flaw in the metal, it seem odd that the split would be through 1 of the strongest parts of the action, I have seen Eddystones that did the same thing after having been drilled and tapped for a scope. If I were to hazard a guess here it would be bad heat treat of the action, coupled with detonation. But like the rest am merely speculating :mrgreen:

 

[death-junky]

oh wow what a boom that must of sucked for the people around him like a granade going off.
talk to ya all later
Riley