jaguarxk120
New member
I always thought the 30-30 headspaced on the rim not the shoulder.
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rechambering 30-30 to 30-30AI
- Thread starter micksis86
- Start date
The 30/30 (rimmed and belted cases) head space on the rim and or belt, in the perfect world the case would head space on the rim and the shoulder, when it becomes a choice the head spacing on the shoulder increases case life by cutting down on all that case travel and the hand loaders insistence on full length sizing the case. For hand loaders there is nothing between full length sizing and neck sizing.
"To get a true Ackley chamber you have to set the barrel back" 'True'.
There are two Ackley chambers, straight out of the box Ackley Improved chamber and The 30/06 chamber that is reamed to Ackley Improved, there are two of those, the set back barrel version and the chamber that is still retains a small portion of the 'Old' chamber. Then there is the one where the operator of the reamer gets creative and makes up things as they go by advancing the reamer beyond specifications, cases will be fire formed, that makes up for some of the mistakes and short cuts.
"An Ackley Improved chamber is a change in the chamber dimensions from the neck-to-shoulder junction back toward the head or rim. The neck-to-shoulder junction does not move. It does not require a barrel set-back if done correctly".
To get a true Ackley chamber you have to set the barrel back.
"Absolutely true. The reason most AI rechamberings get set back is because of most factory chambers being at maximum length and the person doing the rechambering wanting to completely clean up the chamber. But it is not necessary. I have seen several rechambers done by PO Ackley himself that did not completely clean up the chambers in the neck/shoulder junction area"
The two statements above is the reason the question is never answered and when the question comes up again it is the same as starting over, I had this discus ion with a smith in Arizona that went by the name Seaweed. He sent drawings and then went back and reexamined the information he sent, then said "I never noticed that before, the neck on the 30/06 Ackley is longer than the neck on the 30/06 Springfield. We are not talking about the 30/06 or Ackley, we were talking about my methods/techniques, something he described as "Some scary stuff", I also talked to Hodgkin, they said 'IT' will work and I will tell you why.
Back to the genius's of Ackley, and the misconception the datum is in the center of the shoulder (that is imposable), the juncture of the shoulder at the end of the case body moves forward, the juncture of the shoulder at the neck moves back and there is a point on the shoulder that does not move (similar to + caster, move the top forward the bottom moves to the rear when supported in the center. The plan: When the short neck 30/06 is chambered in the Ackley version of the 30/06 the short neck must be sized in the long neck of the Improved chamber (head space, sorta) when fired the case blows out and forms the rest, the shoulder and body, again when chambered the neck is formed when the bolt closes, the rest is formed when the case is fired.
Point being to clean up the chamber the barrel requires setting back, if the barrel is not set back forget head spacing on the neck.
Datum half way between the shoulder to case body juncture and the shoulder to neck juncture and head space gage, done correctly the go-gage is the go-gage, the no-go gage does not become anything but the no-go gage, unless the person operating the reamer designates the no go-gage as the go-gage. The Datum does not chage except on the Internet, meaning the datum on the 30/06 is the same for the Ackley Improved version, 'the genius's of Ackley, same case, head space on the neck juncture, use the same gages.
The 30/06 case neck is .031 thousands shorter than the Ackley Improved neck, going to the no go-gage length gage changes the neck length from .031 to .026 thousands. When going to the 30 Gibbs the shoulder is moved forward .212 rhousands, no barrel set back required.
http://www.z-hat.com/Cylinder.htm
F. Guffey
"To get a true Ackley chamber you have to set the barrel back" 'True'.
There are two Ackley chambers, straight out of the box Ackley Improved chamber and The 30/06 chamber that is reamed to Ackley Improved, there are two of those, the set back barrel version and the chamber that is still retains a small portion of the 'Old' chamber. Then there is the one where the operator of the reamer gets creative and makes up things as they go by advancing the reamer beyond specifications, cases will be fire formed, that makes up for some of the mistakes and short cuts.
"An Ackley Improved chamber is a change in the chamber dimensions from the neck-to-shoulder junction back toward the head or rim. The neck-to-shoulder junction does not move. It does not require a barrel set-back if done correctly".
To get a true Ackley chamber you have to set the barrel back.
"Absolutely true. The reason most AI rechamberings get set back is because of most factory chambers being at maximum length and the person doing the rechambering wanting to completely clean up the chamber. But it is not necessary. I have seen several rechambers done by PO Ackley himself that did not completely clean up the chambers in the neck/shoulder junction area"
The two statements above is the reason the question is never answered and when the question comes up again it is the same as starting over, I had this discus ion with a smith in Arizona that went by the name Seaweed. He sent drawings and then went back and reexamined the information he sent, then said "I never noticed that before, the neck on the 30/06 Ackley is longer than the neck on the 30/06 Springfield. We are not talking about the 30/06 or Ackley, we were talking about my methods/techniques, something he described as "Some scary stuff", I also talked to Hodgkin, they said 'IT' will work and I will tell you why.
Back to the genius's of Ackley, and the misconception the datum is in the center of the shoulder (that is imposable), the juncture of the shoulder at the end of the case body moves forward, the juncture of the shoulder at the neck moves back and there is a point on the shoulder that does not move (similar to + caster, move the top forward the bottom moves to the rear when supported in the center. The plan: When the short neck 30/06 is chambered in the Ackley version of the 30/06 the short neck must be sized in the long neck of the Improved chamber (head space, sorta) when fired the case blows out and forms the rest, the shoulder and body, again when chambered the neck is formed when the bolt closes, the rest is formed when the case is fired.
Point being to clean up the chamber the barrel requires setting back, if the barrel is not set back forget head spacing on the neck.
Datum half way between the shoulder to case body juncture and the shoulder to neck juncture and head space gage, done correctly the go-gage is the go-gage, the no-go gage does not become anything but the no-go gage, unless the person operating the reamer designates the no go-gage as the go-gage. The Datum does not chage except on the Internet, meaning the datum on the 30/06 is the same for the Ackley Improved version, 'the genius's of Ackley, same case, head space on the neck juncture, use the same gages.
The 30/06 case neck is .031 thousands shorter than the Ackley Improved neck, going to the no go-gage length gage changes the neck length from .031 to .026 thousands. When going to the 30 Gibbs the shoulder is moved forward .212 rhousands, no barrel set back required.
http://www.z-hat.com/Cylinder.htm
F. Guffey
Guffey, brickeye, thanks for the info. I was unaware of that, but it makes sense.
I learned something once again. I've been meaning to go measure the neck length on my .30-30 AI vs a normal case. I will do that and bring the numbers back here. Of course it will depend on how my smith did the chamber. He may not have understood this stuff either.
I learned something once again. I've been meaning to go measure the neck length on my .30-30 AI vs a normal case. I will do that and bring the numbers back here. Of course it will depend on how my smith did the chamber. He may not have understood this stuff either.
If you are going to use the method Ackley write up, the go-gauge becomes the AI no-go gauge.
Since every gun should close on the go gauge, you are going to have to set the barrel back if you want to use the go gauge as a no-go gauge and ensure you can fire the original parent cartridge in the new chamber.
You can also cut the chamber as deep as you want, but without a reliable way to headspace the original cartridge you are left with other methods like expanding the neck, then creating a new false neck for initial fire forming.
Part of the attraction of the AI cartridges is the ability to fire the original case safely and form the AI case.
While Ackley may have created other cartridge designs by not setting the barrel back, they are not in keeping with the methods outlined in the Handbook for Shooters.
Since every gun should close on the go gauge, you are going to have to set the barrel back if you want to use the go gauge as a no-go gauge and ensure you can fire the original parent cartridge in the new chamber.
You can also cut the chamber as deep as you want, but without a reliable way to headspace the original cartridge you are left with other methods like expanding the neck, then creating a new false neck for initial fire forming.
Part of the attraction of the AI cartridges is the ability to fire the original case safely and form the AI case.
While Ackley may have created other cartridge designs by not setting the barrel back, they are not in keeping with the methods outlined in the Handbook for Shooters.