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Supposedly Hornady's test gave ~37.5 kpsi for 2050 fps

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Originally posted by Will:
I always find this curious this angst about pressures. How will you ever know what the pressure is in your rifle unless you test for it with different powders, loads, and bullets. Solids seem to have a much higher pressure than softs.

I guess you could always play it "safe" and download to some anemic velocity, but then why have the rifle to begin with?

The max. avg. pressure for the 450/400 3 1/4" is some 2 thousand psi greater than that for the 450/400 3".

Assuming that there isn't a rat's ass difference bwteen two old doubles but one chambered for the 3" and the other for the 3 1/4", what possible sense does it make that one rifle is "rated" at 2+ kpsi greater than the other?

Seems to me that one would want the powder and charge to be sufficient to get the historical, nominal bullet velocity at the lowest possible pressure, but who knows what pressure that is?

Supposedly Hornady's test gave ~37.5 kpsi for 2050 fps with their soft and solid 400 gr. bullets in the 450/400 3" in a 24" barrel. For one thing I don't believe the pressures were the same for solids and softs. So what would be the pressures to have to be to get them going 2150 fps like they are suppose to be, even in a much shorter barrel than the original 28" barrels?

And the 450/400 3 1/4" pressures are higher yet. You going to throw away the rifle, download to 1800 fps and hope, or load 'em up to 2150 fps and shoot them? You don't know the pressures anyway, so what does it really matter?

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Originally posted by asdf:
In its original form, this action (mine is a replica) was chambered for up to the .50-140 Sharps, which modern tests suggest was running around 28 ksi. On seeing the pressure numbers in the A-Square manual, I wondered if the action might be able to produce NE velocities safely.

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The NE pressure ratings would have been established based on what the old loadings needed with Cordite, which was faster than the slower modern powders.

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A-Square was reporting numbers in the low 30's, and my single doesn't need to regulate to double fps. That's why I asked if one really could propel 400 gn to 2150 from a 26" barrel at that pressure.

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Originally posted by Will:
Not sure why my reply is so hysterically funny.

There is nothing to prevent anyone from exceeding the CIP MAP. In some of those 12 lb. 400 hogs what possible difference could there be in 40 kpsi and 45 kpsi?

If 40.6 kpsi is some magical safe limit for the 3", why is 44.2 kpsi "safe" for the 3 1/4" in essentially the same gun? It sounds like the old-timers just jacked up the velocity to where they wanted it and declared that indeed this was the pressure limit. Sounds pretty artificial to me.

Just because someone does some pressure testing on a barrel doesn't mean they have determined any safe pressure limit. I doubt many gun makers have ever done any theoretical calculations or actual burst testing on their rifles.

There is nothing magical about 40 kpsi, other than that is the specification for the 3" case. Somehow all that magic is forgotten when the same or even much lighter weight double rifles are built for high pressure rounds such as the 375 H&H and the 458 WM which operate at as much as 20 kpsi higher pressures.

You seem to think that operating a 3" above 40 kpsi is some sort of heresy, but that doesn't mean you can't do it, or do it safely.

And, no, I do not believe that Hornady solids and softs operate at the same pressure for the same velocity, 2050 fps.

They compared their loads to Kynoch factory loads in order to keep under the lawsuit radar. But that doesn't mean you can't soup up reloads. At 2050 fps in a 24" barrel, they are so anmeic that I wonder why anyone would bother, other than to sustain traditionally anemic loads. Of course you could have a 28" barrel gun to achieve the 2150 fps, but the rifle just gets heavier and less handy.

And indeed in an old, heavy 450/400 the shooting is "pleasant" but it depends on what use you intend for it. Shooting deer and pigs is more easily done using a lightweight 9.3 x 74R than a 450/400. For dangerous game I don't want to haul that 10 or 11 pound hog around in the heat.

The only point that I can see to a 450/400 is the ability to have a lightweight double rifle made using the round. If you want a hog, might as well go up to a 470 or similar.

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Originally posted by Tim Carney:
Interesting here. I'm travelling and far from my books, but didn't Graeme Wright actually do some load testing for doubles that included both of the 450/400s? His facts might contribute to the discussion.

Regards