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Re: Need info explosive!!!!!!!!!
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RMiller
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Picture of RMiller
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http://www.thegunzone.com/m1akb.html

Interesting article.
 
Posts: 9823 | Location: Montana | Registered: 25 June 2001Reply With Quote
Hot Core
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... HotCore, I followed the thread you refered to, both here and at 24hr campfire while it was running. The problem Mr Sisk and Denton reported was with "normal" charges of slow powder under a light for caliber bullet, not a reduced load.
Mr Sisk blew the brake on his rifle by questioning the test equipments report of a spike and adding powder. This is a bit different then a lower then recommended charge causing a mishap, although the resulting pressure wave may well be similar. Both reported to be able to achive similar results (secondary pressure excursions) at will useing selected componts but not at reduced charge levels. IE: Light for cal bullets and listed recommended charges of very slow powders.
I agree with you, one should stay with listed charges and not excede or go below them. The writers of the manuals have a reason for the min / max they list and I suspect they know more about secondary spikes then they let out to the public....

Hey Ol` Joe, I agree with you. As I look at what I wrote before, I was not as clear about what I was trying to get across as I should have been.

The flicks of the Pressure Curves the young fellow added in that thread DO NOT show an actual Secondary Explosion Effect. What it does show is how it goes about occurring.

All a person has to do is visualize the First Pressure Rise shown in that flick as a bit lower(less Pressure) and for a slightly shorter time duration(farther to the left). Then visualize that Second Pressure Spike being three times as tall(3x the Pressure) and move it half a screen to the left(less time before it occurs) and you will have a "Mental Image" of an actual Secondary Explosion Effect.

There are lots of things that have the potential to cause the situation. An excellent list of them has been provided for all of us by Mr. Ackley in his Two Volume set.

One of the things he mentioned included input from the old Cascade Cartridge Inc (CCI). They were working on a "new" Primer mix back then. And they believed what could possibly be happening was their "new" Magnum Primer mix could be igniting at such a Pressure level that it actually "broke" IMR-4831 into smaller pieces which drastically altered it's burning rate. Amazing!

Hard to say what actually blewup the guns mentioned in this thread. But, I do believe in it. No argument with folks that don't believe in it, fine by me.

Best of luck to all you folks!
 
Posts: 9920 | Location: Carolinas, USA | Registered: 22 April 2001Reply With Quote
<eldeguello>
posted
Bren, I can support you on that load! When I got my Ruger No.1B in 7mm Rem. Mag. in 1969, I worked up two loads for it using old surplus H4831 I had purchased 8 pounds of in a GI. powder can in 1968. One load came out to 71.5 grains of it with the 140-grain Nosler Partition bullet of that day & age, and it produced 3400 FPS MV chronographed with an ITCC chronograph which used two wires 10' apart to start & stop the counter. Later, this same 140-grain load produced 3375 FPS @ 10' chronographed with an Oehler, and later, a Chrony Beta model using the same powder and the new-style Nosler Partition 140 grainer.



The other load was worked up with the Nosler 175-grain Partition, and came out to be 66.5 grains of that same surplus H4831 and a MV of 3070 FPS. An identical charge, 66.5 grains, of old Norma N205 gave the same velocity, and slightly better accuracy (1" @ 200 yards!). I had no indications of excessive pressures with any of these loads, and I am convinced that the old surplus H4831 gave higher velocities at lower pressures than the new H4831, and the old stuff took a heavier charge to do it! I wish I still had some of the old surplus stuff!
 
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