Handbook for Shooters and Reloaders

[Gibbs505]

Handbook for Shooters and Reloaders

By P. O. Ackley

This is another book that I picked up at a garage sale. I really recommend looking for books this way!

The copy I have is dated 'Copyright, 1962' so I cannot recommend any of the handloading data due to advances in smokless powder, inculding the introduction of many new powders. Always use the most current information available. Please!


There is however much fasincating information, inculding some on wildcats based on the 303 British case. The book is also a good place to start if you are looking for information about old and obscure cartridges.

As well, you can read about expirements performed on barrels, actions and in measuring wind drift, sectional density, headspace and bore capaicity. Yes we can all get this much easier from a ballistice program but it is interesting to see what the reloader had to go through in "the good old days".

Iff you want to build your own pendulum chronograph,all the details and plans are in this book as well! After all, who wants to do the easy thing all the time!

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[John Lawson]

Some of the wildcats mentioned are the product of Jerry Shannon's ballistic experiments. My father-in-law introduced me to Jerry in 1951, when he had a shop outside Tacoma, Washington, on the montain highway. I was completely mind-boggled by the array of converted Springfield, Enfield and Krag rifles in his gun racks. Unfortunately, the Korean war interrupted my plans for buying a Krag sporter from him.

[Gibbs505]

Wow, John, that is really interesting. I would have loved to have met some of these pioneers!

[Andy]

I have both volumes of his work and they are well worth while reading. Keep in mind that Mr. Ackley (like Rocky Gibbs) had some commercial interests and many of his claims concerning performance increases from "improving" a cartridge have since been debunked. His claim that straightening the taper on cartridges reduces bolt thrust has possibly generated the most controversy. In fact bolt thrust is a simple product of case head diameter and pressure, having nothing to do with the shape of the case, understanding that in a dry (non-oiled) chamber, the brass grips the chamber walls, and only the unsupported part (the casehead) stretches back against the bolthead. That doesn't mean that less taper and sharper shoulders doesn't decrease brass "flow" (and hence increase brass life), just that the notion of a tapered cartridge "squirting" out of a chamber is a myth.

[Gibbs505]

I have both volumes of his work and they are well worth while reading. Keep in mind that Mr. Ackley (like Rocky Gibbs) had some commercial interests and many of his claims concerning performance increases from "improving" a cartridge have since been debunked. His claim that straightening the taper on cartridges reduces bolt thrust has possibly generated the most controversy. In fact bolt thrust is a simple product of case head diameter and pressure, having nothing to do with the shape of the case, understanding that in a dry (non-oiled) chamber, the brass grips the chamber walls, and only the unsupported part (the casehead) stretches back against the bolthead. That doesn't mean that less taper and sharper shoulders doesn't decrease brass "flow" (and hence increase brass life), just that the notion of a tapered cartridge "squirting" out of a chamber is a myth.

No completely, consider the Remmington "Jet" 22 cal revolver. That had a tapered case and caused a great deal of problems by backing out of the chamber when fired and jamming the cylinder.

The revolver and cartridge were both dropped.

[John Lawson]

Depends a great deal on what powder and the load used. Obviously, it takes longer for pressure to empty out of a vessel closed on one end to pass through a smaller hole, yet it passes more quickly through a semi-venturi shape. And, recent laboratory tests show that the powder wads up at the mouth of a necked case, creating a delay and resulting in more pressure. The greater the internal pressure, the greater the case stretch can be, if several factors are present.
The half caste putdowns do not consider that Ackley was using powders not available today that had different burning characteristics. And, nobody even will tell you the water capacity of the case being tested; a factor that has a profound effect on pressure peak, time and brass stretch. Very unscientific, but very convenient for an experimenter who is not an expert in internal ballistics to convince an editor, who is a wordsmith, not a gunsmith to print his rant.
I was also going to mention the .22 jet vs the .22 jet improved and some other common cartridges of that pattern.
A few years back, when several powder makers had bad accidents and new sources of the powder were found and marketed, I had to destroy years of tests, since the newer powders were entirely different in respect to the length of time at peak pressure, etc.
Never forget water capacity and that elusive fourth dimension, time.
Incidentally, it was George Leonard Herter who first debated the value of "improved" cases (see his book "Professional Loading"). Although he was an Ordnance officer during WW-II and the inventer of the Garand winter trigger, his sole claim to internal ballistics knowledge was a few visits to FN and conversations with some of the enginers in Belgium. One wonders, if standard products (such as cartridges) are the ultimate, as he purports, why he spent most of his life looking for modifications. And, why he purported to teach American males to auccessfully get along with a woman by self-publishing a book titled "How to Live with a Bitch."

[Andy]

There's a good discussion on Ackley and Bolt Thrust at Shooter's Forum Article posted on Precision Shooting Website about Ackley Improved cartridges - Shooters Forum

Ackley's famous test whereby he fired an "improved" cartridge unsupported by a bolt, and it stayed put upon firing, has been repeated several times, as have supposed "control" tests that used an standard high-taper (unimproved) case that upon firing was ejected with great vigour rearwards. These "tests" have served as sufficient proof for generations of Ackley afficiandos that bolt thrust is essentially eliminated when taper is removed. I don't disagree with the observations, but do strongly disagree with the usual conclusions.

First off, you can only test bolt thrust with a bolt in place. Secondly, even if you can conclude that the more taper, the more rearward force on the case, these tests speak nothing to the magnitude of the difference. For all we know, the application of finger pressure might have been enough to keep the tapered case in place long enough for the brass to grip the chamber walls. If for the first critical microsecond (or less), there is no rearward resistance, the case cold move enough rearwards to create sufficient case-chamber clearance to leave nothing to be gripped.

[John Lawson]

In that internal pressure from an ignited cartridge acts equally in all directions, bolt head pressure is equal to the presure exerted on the chamber walls. If there is any slack in bolt lockup, there will be some case rearward movement. At no time during the ignition of a cartridge does the bolt "thrust rearward" differently due solely to cartridge shape. Straightening out the walls of a case and making a similarly shaped chamber will DECREASE THE PRESSURE in the chamber at peak. This is only incidentally due to a change in wall shape. It is primarily due to an increase in water capacity of the case internally, resulting in less peak chamber pressure and therefore less thrust against the bolt face, chamber walls and bullet. And a very little change makes a very big difference with some powder types and loads; not so much with others.
Some early experimenters took advantage of the capacity increase to pack in more powder, resulting in what was called "overbore loading." We won't even go there.
Little was known about internal ballistics in the 1940's, and it has only very recently been explored in depth in publications such as Precision Shooting.
Very often, ballistic experimenters come up with the what of something but not the all essential why.