Powley psi Calculator

[abunaitoo]

Found this.
Powley psi Calculator
Hutton Rifle Ranch
Greenleaf Canyon,
Topanga Calafonia
Also have the letter shipped with it.
Kind of a slide rule powder calculator
It says something about a "Powley Hand Loading Computer"
Don't think I have it, but it may turn up.
I've heard of this thing, but never tried it.
255173255174

[Red River Rick]

They work great for working up a load.

255171

[Larry Gibson]

Back in the late '60s when I began studying ballistics (all 3 phases) I got the Dupont charts, the Powley computer and Speer's ballistic computer. All were useful at the time but I quickly learned that the more accurate I was in input the more accurate was the output from all of them. It's the same with QuickLoad and other ballistic calculators today. Input of correct and complete information is necessary for accurate output of data. I was even more impressed with that fact that they were just "estimations" when I got my first Oehler chronograph in '74. I found that velocity estimations with any such "calculators" were just that; an estimation. When I got the Oehler M43 PBL 12 years ago and actually started measuring pressures and ballistic coefficients that fact was even more apparent.....garbage in always equaled garbage out. However, once I got used to using the charts and computers (slide rules) I found, after actually measuring velocities, pressures and coefficients, that the results could be closer than attempting to use interpolated velocity and/or pressure from data in reloading manuals. One important thing I learned as to velocities and BCs; we want to be optimistic and round up.....don't. Rounding down will give better results of more realistic numbers. With pressure calculation it's best to round up and assume the pressure is higher...…

Also, they are just a tool. It's best not to use them to determine a load, especially a max load, and then go load it. Always work up and use them as a guide, as a tool in that process.

255176

[Outpost75]

^^^^What Larry said^^^^

What most amused me when visiting BRL on a project back in the 1970s, we were discussing how to measure nutation and precession on a projectile, calculating yaw drag and gyroscopic stability factor, Dr. Robt. L. McCoy explained how they just installed instrumentation in a 40mm homologue projectile, fired it and measured it. By the 1980s they could miniaturize it to fit it down to a cal. .50, now who knows...

The Oehler machinegun chronograph of that era was facinating... As was firing backwards into the transonic aerodynamic range at night and taking spark shadowgraphs of 168-grain M852 as transonic buffeting occurred as velocity decayed beloqw the speed of sound at about 700 meters, which resulted in development of the 175 MK used in the M118LR sniper ammo.

[RU shooter]

My Dad still has his he bought in the early 60's

[Mr Peabody]

I bought one in the 90's. I used it to work up loads for the .33 Winchester. Information for that round was scarce, this helped me get going. Hutton Rifle Ranch was in Boise Idaho by then.

[dverna]

I have one as well.

Showing my age I guess.