What does Ackley Improved mean?
- Thread starter jdp3
- Start date
VirginiaCoyote
New member
Excellent question I've often wondered that myself I'm very interested to see some replies.
RandyDB
Active member
This will tell you all about it.
http://en.wikipedia.org/wiki/P._O._Ackley
http://en.wikipedia.org/wiki/P._O._Ackley
Mousedipper
New member
I will give it a try.
Sometime in the past there was a gent named P.O. Ackley who was involved in wildcatting existing cartridges. His modus operandi was generally reaming out the chamber of many different cartridges to lengthen, remove some taper, and make a sharper shoulder, Usually 40 degrees instead of the standard 23 or whatever.
He made claims of 2 to 3 hundred fps improvement over the parent cartridge. Usually it was more like 50 to 100 fps improvement.
Normally the parent cartridge could still be fired in the improved chamber which in turn "fire formed" the brass to the new dimensions.
Most reloading die makers carry Ackley improved dies with varying shoulder angles. They are usually more expensive than standard dies.
There are also claims that Ackley improved cartridges are generally more accurate than the parent cartridge, but I cannot verify this claim.
I have been interested in the Ackley improved versions of several calibers, but never enough so to have any of my firearms "Improved"
Hope that sheds some light on the subject but I may have left out some important details, as I don't claim to be well versed on the subject.
Dave
Sometime in the past there was a gent named P.O. Ackley who was involved in wildcatting existing cartridges. His modus operandi was generally reaming out the chamber of many different cartridges to lengthen, remove some taper, and make a sharper shoulder, Usually 40 degrees instead of the standard 23 or whatever.
He made claims of 2 to 3 hundred fps improvement over the parent cartridge. Usually it was more like 50 to 100 fps improvement.
Normally the parent cartridge could still be fired in the improved chamber which in turn "fire formed" the brass to the new dimensions.
Most reloading die makers carry Ackley improved dies with varying shoulder angles. They are usually more expensive than standard dies.
There are also claims that Ackley improved cartridges are generally more accurate than the parent cartridge, but I cannot verify this claim.
I have been interested in the Ackley improved versions of several calibers, but never enough so to have any of my firearms "Improved"
Hope that sheds some light on the subject but I may have left out some important details, as I don't claim to be well versed on the subject.
Dave
I.O.N.Doyle
New member
Quote:
but what does ackley improved mean?
It means that I am going to give it a go on one of my rifles and my wife is going to be severly PO'd when she sees the bill.
but what does ackley improved mean?
It means that I am going to give it a go on one of my rifles and my wife is going to be severly PO'd when she sees the bill.
Ridge Runner
New member
ok, mouse had most of it correct, but actual P.O. did get the gains he claimed, mostly because he was running his wildcats overpressure.
Most reloaders know that when you see the signs of pressure they are as follows
1) flattened primers
2) ejector pin marks
3) quickly accompanied by sticky extraction and heavy bolt lift
Well if ya start shooting an AI or any sharpshouldered case with a custom reamer without all the slop built in, you don't see this. without the 23 degree shoulder and alot of body taper acting like a tapered wedge pushing against the bolt the first pressure sign you notice is the ease of seating a new primer. this means casehead expansion and that is the #1 sign of over pressure.
In other words, when you notice pressure signs in an AI'd chamber, that case is much closer to failure than a 30/06 with ejector pin marks.
without running them over pressure for gains in velocity, the main advantage to an AI chamber is the fact that the sharp shoulder holds back the flow of brass so trimming is held to a minimum.
RR
Most reloaders know that when you see the signs of pressure they are as follows
1) flattened primers
2) ejector pin marks
3) quickly accompanied by sticky extraction and heavy bolt lift
Well if ya start shooting an AI or any sharpshouldered case with a custom reamer without all the slop built in, you don't see this. without the 23 degree shoulder and alot of body taper acting like a tapered wedge pushing against the bolt the first pressure sign you notice is the ease of seating a new primer. this means casehead expansion and that is the #1 sign of over pressure.
In other words, when you notice pressure signs in an AI'd chamber, that case is much closer to failure than a 30/06 with ejector pin marks.
without running them over pressure for gains in velocity, the main advantage to an AI chamber is the fact that the sharp shoulder holds back the flow of brass so trimming is held to a minimum.
RR
IDBob
New member
One thing it does mean for folks that deal with buying and selling guns is a pretty good devaluation in your rifle when it comes time to sell or trade it.
When one of the Ackley improved guns would come into the store it was much harder to sell than a standard chambered rifle. This means that I devalued it a bunch on a trade or when buying it.
You may gain some velocity, but at the expense of having to spend money on dies and chambering. Unless you plan to keep that gun for a long time your not only going to loose money in the work done on it and the cost of specialty dies, but most dealers simply don't want one on their shelves because they are extremely hard to sell.
If you want more velocity my suggestion would be to simply move up to a bigger case in the same caliber than rechamber to a non-standard cartridge.
OK guys don't jump all over me now, cause there are two sides to every story.
When one of the Ackley improved guns would come into the store it was much harder to sell than a standard chambered rifle. This means that I devalued it a bunch on a trade or when buying it.
You may gain some velocity, but at the expense of having to spend money on dies and chambering. Unless you plan to keep that gun for a long time your not only going to loose money in the work done on it and the cost of specialty dies, but most dealers simply don't want one on their shelves because they are extremely hard to sell.
If you want more velocity my suggestion would be to simply move up to a bigger case in the same caliber than rechamber to a non-standard cartridge.
OK guys don't jump all over me now, cause there are two sides to every story.
bkhcj8
New member
Quote:
Ok so far so good. Give me an example of a cartridge that was Ackley improved.... so what caliber brass did they start with to come up with the AI'd 243 brass, etc... and so the positives greater fps than you would normally have out of that cartridge???
I'll try to help pretty much you start with a 243 then have it reamed to make it ackley improved, you then shoot the standard 243 bullets in the gun and the presure from the powder going off makes the case expand to the new reamed size. Which only makes it longer not bigger. This is called fire forming. Once the case has been fire formed and made to the new 243 AI you can use another set of 243 AI dies and start reloading the brass as a 243 AI. Extra time, extra dies, extra powder, extra bullets because the fire forming is pretty much a waste of a bullet, and not a lot of extra results. There a lot of people that swear by a AI gun but I never thought much of them. Alos as stated above its hard to sell or trade one to a normal hunter.
Ok so far so good. Give me an example of a cartridge that was Ackley improved.... so what caliber brass did they start with to come up with the AI'd 243 brass, etc... and so the positives greater fps than you would normally have out of that cartridge???
I'll try to help pretty much you start with a 243 then have it reamed to make it ackley improved, you then shoot the standard 243 bullets in the gun and the presure from the powder going off makes the case expand to the new reamed size. Which only makes it longer not bigger. This is called fire forming. Once the case has been fire formed and made to the new 243 AI you can use another set of 243 AI dies and start reloading the brass as a 243 AI. Extra time, extra dies, extra powder, extra bullets because the fire forming is pretty much a waste of a bullet, and not a lot of extra results. There a lot of people that swear by a AI gun but I never thought much of them. Alos as stated above its hard to sell or trade one to a normal hunter.
IDBob
New member
They always start with a standard caliber or standard case. Such as the 30-06 makes into the 30-06 Ackley improved. The 270 into the 270 Ackley improved and the 243 Remington into the 243 Ackly improved.
Basically a tapered case is blown out straight and the shoulder angles made sharper to give the case both more grip on the chamber walls (straighter cases do that) and a little more powder capacity. They are also loaded somewhat hotter (more pressure than most standard cartridges).
Basically a tapered case is blown out straight and the shoulder angles made sharper to give the case both more grip on the chamber walls (straighter cases do that) and a little more powder capacity. They are also loaded somewhat hotter (more pressure than most standard cartridges).
Last edited:
Mousedipper
New member
JDP3,
I think what everyone is trying to say, is now that you know what it is, You really don't need it.
Bullet placement is always more important than a couple of hundred extra feet per second.
Dave
I think what everyone is trying to say, is now that you know what it is, You really don't need it.
Bullet placement is always more important than a couple of hundred extra feet per second.
Dave
bea175
New member
Improve the case means you increase the efficiency of the case without pushing the pressure to dangerous levels. Some case really benefit from improving and some don't . Cases that have the most benefits are the 22-250, 257 Robert , 250 Savage, 280 Rem , 243 Win and some that don't are the 30-06 , 270 Win , 25-06. Gaining 100 to 200 fps sometimes is the difference between a Magnum and the Standard Cal's. If you don't mind the fire forming of the case then the Ack can give you close to magnum performance in a standard cal. I like them, another plus, it almost eliminates trimming cases.
Bayou City Boy
New member
Quote:
I will give it a try.
Sometime in the past there was a gent named P.O. Ackley who was involved in wildcatting existing cartridges. His modus operandi was generally reaming out the chamber of many different cartridges to lengthen, remove some taper, and make a sharper shoulder, Usually 40 degrees instead of the standard 23 or whatever.
He made claims of 2 to 3 hundred fps improvement over the parent cartridge. Usually it was more like 50 to 100 fps improvement.
Normally the parent cartridge could still be fired in the improved chamber which in turn "fire formed" the brass to the new dimensions.
PO never lengthened the chamber of any cartridge. In fact, a true AI chamber can only be cut after a standard cartridge barrel has been set back one or two threads.
The reason for this is that the head space dimension for an AI cartridge is actually shorter than the standard cartridge.
If you just ream a factory chamber out completely with an AI reamer, you're going to have an AI chamber with excessive head space. As a result you'll believe that all AI cartridges have to have bullets jammed into the barrel lands to fire form cases, and you'll constantly complain that you are having case separation problems with your AI rifle, etc.
Neither of those needs/problems exits with a properly cut AI chamber. And.....You will actually experience a slight tight feeling or "crush" closure on a bolt when chambering a factory round in a properly cut AI chamber.
And PO never advertised increased velocity as a primary reason to improve a cartridge. He was more interested in controlling bolt thrust and cartridge length growth with his designs in a time when a lot of suspect (in terms of strength) liberated military rifle actions were being used for sporter conversions than he was with building "hot rod" cartridges. Others grabbed the "more velocity" mantra and ran with it much more than he ever did...
-BCB
I will give it a try.
Sometime in the past there was a gent named P.O. Ackley who was involved in wildcatting existing cartridges. His modus operandi was generally reaming out the chamber of many different cartridges to lengthen, remove some taper, and make a sharper shoulder, Usually 40 degrees instead of the standard 23 or whatever.
He made claims of 2 to 3 hundred fps improvement over the parent cartridge. Usually it was more like 50 to 100 fps improvement.
Normally the parent cartridge could still be fired in the improved chamber which in turn "fire formed" the brass to the new dimensions.
PO never lengthened the chamber of any cartridge. In fact, a true AI chamber can only be cut after a standard cartridge barrel has been set back one or two threads.
The reason for this is that the head space dimension for an AI cartridge is actually shorter than the standard cartridge.
If you just ream a factory chamber out completely with an AI reamer, you're going to have an AI chamber with excessive head space. As a result you'll believe that all AI cartridges have to have bullets jammed into the barrel lands to fire form cases, and you'll constantly complain that you are having case separation problems with your AI rifle, etc.
Neither of those needs/problems exits with a properly cut AI chamber. And.....You will actually experience a slight tight feeling or "crush" closure on a bolt when chambering a factory round in a properly cut AI chamber.
And PO never advertised increased velocity as a primary reason to improve a cartridge. He was more interested in controlling bolt thrust and cartridge length growth with his designs in a time when a lot of suspect (in terms of strength) liberated military rifle actions were being used for sporter conversions than he was with building "hot rod" cartridges. Others grabbed the "more velocity" mantra and ran with it much more than he ever did...
-BCB
Ridge Runner
New member
jdp, the good part about ai'd chambers is, say take a 243 AI, you can shoot regular 243 win ammo in it to make AI'd cases. to rechamber a 243 win to 243 AI, you need to set the barrel back at least .004", the AI chambers are that much shorter than its parent (the neck shoulder junction is .004 shorter on an AI chamber than its factory production parent) hope this helps.
RR
RR
Rustydust
Active member
Quote:
JDP3,
I think what everyone is trying to say, is now that you know what it is, You really don't need it.
Bullet placement is always more important than a couple of hundred extra feet per second.
Dave
Well said, Mouse!
If you miss a prairie dog (coyote, fox, jackrabbit, etc) at 400 yards with your standard cartridge, you are going to miss him just as handily with the "improved" version of the same round.
Having said that, I still have the hots for a neato keen custom rifle in 257 Roberts Improved, 40 degree shoulder, natch! /ubbthreads/images/graemlins/grinning-smiley-003.gif
JDP3,
I think what everyone is trying to say, is now that you know what it is, You really don't need it.
Bullet placement is always more important than a couple of hundred extra feet per second.
Dave
Well said, Mouse!
If you miss a prairie dog (coyote, fox, jackrabbit, etc) at 400 yards with your standard cartridge, you are going to miss him just as handily with the "improved" version of the same round.
Having said that, I still have the hots for a neato keen custom rifle in 257 Roberts Improved, 40 degree shoulder, natch! /ubbthreads/images/graemlins/grinning-smiley-003.gif
Ackman
New member
The AI cartridges have been discussed half to death. After all the posts about them it's hard to believe the misconceptions and flatout nonsense you still see when the subject comes up again. Mostly by people who don't shoot them and have no idea what they're talking about. A lot of these posts are just plain wrong. This is a good example.
Quote:
Quote:
Extra time, extra dies, extra powder, extra bullets because the fire forming is pretty much a waste of a bullet, and not a lot of extra results. There a lot of people that swear by a AI gun but I never thought much of them.
Dies are unique, but loading time is the same. Fireforming the waste of a bullet? Are you nuts? Fireforming happens as a result of just shooting. Fireform velocities are somewhere about midway between the standard cartridge and the formed case, but sometimes more. They're extremely usable and accurate. Saying it's a waste is just plain wrong.
These cartridges all give faster velocities than the parent case. You can look at a case and pretty much tell if there'll be just some increase in velocity, or a lot. How much more depends on how much body taper the original case has, original shoulder angle to some extent, and bullet weight. Then, how well the loads have been worked up....some people just choose the wrong powder. But there WILL be an increase. People saying it's hardly anything simply don't know what they're talking about......you'll find they're also the ones who don't have them and pull their numbers from a reloading manual, or never spent time making one work. That's how it is.
Quote:
Quote:
Extra time, extra dies, extra powder, extra bullets because the fire forming is pretty much a waste of a bullet, and not a lot of extra results. There a lot of people that swear by a AI gun but I never thought much of them.
Dies are unique, but loading time is the same. Fireforming the waste of a bullet? Are you nuts? Fireforming happens as a result of just shooting. Fireform velocities are somewhere about midway between the standard cartridge and the formed case, but sometimes more. They're extremely usable and accurate. Saying it's a waste is just plain wrong.
These cartridges all give faster velocities than the parent case. You can look at a case and pretty much tell if there'll be just some increase in velocity, or a lot. How much more depends on how much body taper the original case has, original shoulder angle to some extent, and bullet weight. Then, how well the loads have been worked up....some people just choose the wrong powder. But there WILL be an increase. People saying it's hardly anything simply don't know what they're talking about......you'll find they're also the ones who don't have them and pull their numbers from a reloading manual, or never spent time making one work. That's how it is.
bkhcj8
New member
Well ACKMAN, I have shot them and have owned a few 257AI. I also have a pretty good idea what I am talking about when it comes to tha AI cartridge. I may not have the amount of post you have here however I have been reloading a lot longer than the amount of post and the amount of time I have here at PM. Most of my family shoot them and are fans of the AI. It does take extra time to load them because you have to load them once for a standard load to fireform then you have to reload to have a AI round. So that is twice the load time to have a AI round. You are right fireforming is just part of shooting and the gun is just as accurate, but the first load is not AI even though you are shooting it out of a AI chamber, so if you are wanting to shoot a AI gun you have to run through a few rounds to create a case for reloading. That seems like a waste of bullets to me. Sure you can go out and shoot all the standard cases you want out of an AI gun but thats not the end result a person is looking for when they build an AI rifle. Alos there is extra powder involved, how do you think the bullet gets its extra velocity.
AaronC
New member
Sometimes Ackley Improved cartridges make sense. It is a lot easier and cheaper to come up with 22/250 AI brass than it is 220 Swift brass (by fireforming factory ammo in the 22/250 AI chambered gun).
Many people buy guns because they want to be unique. Do we really need any hunting cartridges besides 30/06 and .375 H&H? Well, not really, as they will do anything they need to. So why do we have the 50+ or so cartridges we do, people just want something else!
I came across a 1910 Mexican Mauser, what to do with it? It is now a 257 AI. Nice shooting gun and it was my first foray into wildcat chamberings. It has a certain rightness about that cartridge in a gun with a 3" magazine box.
Aaron
Many people buy guns because they want to be unique. Do we really need any hunting cartridges besides 30/06 and .375 H&H? Well, not really, as they will do anything they need to. So why do we have the 50+ or so cartridges we do, people just want something else!
I came across a 1910 Mexican Mauser, what to do with it? It is now a 257 AI. Nice shooting gun and it was my first foray into wildcat chamberings. It has a certain rightness about that cartridge in a gun with a 3" magazine box.
Aaron
bea175
New member
My biggest reason for building rifles on the Improve case are, i like using and having rifles other don't have, plus i very seldom shoot a factory round in my rifles so loading for the improve case is no big deal for me. The last fifty cases i formed for my 280 Ack i used Cream of Wheat and Unique, so no wasted bullets. Taking the extra time for the Ack's is well worth it for me. I just received 50 New Nosler 280 Ack cases already formed so no work this time other than just loading them. Remember one thing about improved case they are no magic in them , you will gain a little velocity in some and almost none in others depending on the barrel, chamber and cal.