Saw this on another forum thought I would post it here.

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Re: Saw this on another forum thought I would post it here.

Post by Ranch Dog »

In reference to the cast bullet issues with the 500 S&W, it is not so much the velocity but the pressure behind the velocity. This is what makes things happen. The 500 S&W is a 61.9 KPSI cartridge, normally the cartridge would be loaded to something in the order of 54.2 KPSI. You really never run a cartridge at it's absolute pressure as then the standard and extreme pressure spreads are not contained within the max. Just like velocity, powder burning experiences anywhere up to about a 15% deviation in a target pressure. Any load data takes this into consideration.

Trying to get a bullet to survive the 54.2 KPSI is the trick. It will take alloy beyond the typical wheel weights, a bought alloy, and it will take heat treating that alloy (oven heating). This is the same story with the 454 Casull. It's Pmax is 65.0 KPSI with a target pressure of 56.9 KPSI. The 480 Ruger is a better bet for the cast bullet shooter in that it's performance is produced at a lower pressure, 47.9/41.9 KPSI. This is do able with the average alloys.
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Re: Saw this on another forum thought I would post it here.

Post by akuser47 »

I had figured you would have the pressure info that I didn't for this thanks RD
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Re: Saw this on another forum thought I would post it here.

Post by pricedo »

Ranch Dog wrote:In reference to the cast bullet issues with the 500 S&W, it is not so much the velocity but the pressure behind the velocity. This is what makes things happen. The 500 S&W is a 61.9 KPSI cartridge, normally the cartridge would be loaded to something in the order of 54.2 KPSI. You really never run a cartridge at it's absolute pressure as then the standard and extreme pressure spreads are not contained within the max. Just like velocity, powder burning experiences anywhere up to about a 15% deviation in a target pressure. Any load data takes this into consideration.

Trying to get a bullet to survive the 54.2 KPSI is the trick. It will take alloy beyond the typical wheel weights, a bought alloy, and it will take heat treating that alloy (oven heating). This is the same story with the 454 Casull. It's Pmax is 65.0 KPSI with a target pressure of 56.9 KPSI. The 480 Ruger is a better bet for the cast bullet shooter in that it's performance is produced at a lower pressure, 47.9/41.9 KPSI. This is do able with the average alloys.

What is the paradigm SAAMI uses in the determination & setting of the max pressure for a given cartridge :?:
Is the max pressure set at the absolute theoretical failure point of the system or is there a safety factor built in :?:
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Re: Saw this on another forum thought I would post it here.

Post by Ranch Dog »

This is from the SAAMI Voluntary Performance Standards, the Explanation of Pressure Terminology. With each cartridge, the standard for each of these terms is listed.
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This is where the use of personal pressure trace equipment comes to use, especially if you want to maximize the potential of any given cartridge. This equipment will measure and calculate the deviations of a specific lot of powder so that you can load closer to the max without any risk. Of course the equipment does more that that. I think the best feature is measuring barrel timing. This is determining the load so that the bullet passes through the muzzle at the null of the barrel as the barrel oscillates from recoil. The barrel flexes through the null several times and a load can be calculated to match bullet exit with the motion. Once you know the timing, you know a lot about what is always going to work best on the accuracy end. QuickLoad can calculate the "B_Tim ms" of a load or match a load to the time, it just cannot measure it. Having the equipment make the two pieces of technology, pressure trace and Quick Load, a great investment.
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Re: Saw this on another forum thought I would post it here.

Post by 0369 »

I like it, but would rather have a '71 in 450 Alaskan. I like the rear sight except on the Gunblast site, it shows a picture from the back and it's clearly meant for a round barrel. For a $2000+ rifle, it looks like a horrible after thought. It does give me an idea for a rear sight on my 92 though adding another project to my long list.
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