Ackley Improved calibers
Are AI cases like the .243AI made by fire forming the standard round in the AI chamber?
Is the MAIN reason for AI to increase velocity or is it to improve accuracy.
I know about the .222AI .243AI, what other calibers are also Ackley Improved?
Is the MAIN reason for AI to increase velocity or is it to improve accuracy.
I know about the .222AI .243AI, what other calibers are also Ackley Improved?
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Bruce,
Are AI cases like the .243AI made by fire forming the standard round in the AI chamber?
Yes, this is what separates an Ackley or Ackley style chambers from other wildcats.
Is the MAIN reason for AI to increase velocity or is it to improve accuracy.
Shooting standard brass in an Ackley chamber 'blows out' the body of the case and creates the 40 degree shoulder which typifies the Ackley style. The blown out body has less taper per side which increases the case capacity. Increased case capacity can allow for higher velocities. The 40 degree shoulder creates the potential for more efficiency in the powder burn which can yield higher velocities. The sharper shoulder also curtails the growth of cases reducing the number of times that a case needs to be trimmed. However, one of the drawbacks to an Ackley chamber is that the cases do not show signs of higher pressure in the same way that standard chambers and cases do.
Nowadays, almost every cartridge can be made in the Ackley style but P.O. Ackley isn't responsible for a lot of them. You can get a copy of his 2 volume set of books from Brownells, which has a short synopsis of most of the cartridges that he worked with, Ackley or otherwise.
Best.0 -
Yes, Yes, No, a whole bunch. The benefits of Ackley's series was primarily to increase velocity, but in cases with sloping bodies, straightening them out also help caselife. 0 -
I own many AI calibers - 257 Roberts AI, 25-06 AI, 280 AI, and a 30-06 AI. I've shot them extensively, experimented with essentially all modern powders, and chronographing each round. My guns are "trued-up" bolt actions (Rem 700 or Win M70) with custom barrels. Here are some of my findings.
First, accuracy is no different than the standard caliber - indeed, accuracy is more a function of the gun, especially the quality of the barrel.
Next, case life is increased, if the case doesn't fail during fire-forming - after that neck stretching is reduced by the 40 degree shoulder.
Pressure signs are identical to pressure signs in the standard caliber. Pressure signs are a function of the "hardness" of the brass you're using, with significant pressure signs beginning to show at ~65,000 psi. I wouldn't load past ~65,000 psi.
Please keep in mind that the 30-06 AI is only a small improvement over the regular 30-06 - that is, ~7% increase in case capacity. For example, with Alliant Reloader 25, I can tap in ~66 grains in a Winchester case, for a 30-06 AI case I can tap in ~71 grains - both filled just below the top. Then you compress those super charges with a 180 grain Nosler BT, and you'll get ~3000 fps with the regular 30-06 and ~3100 fps with the 30-06 AI. Pressure will be ~65,000 psi, and primer pockets will loosen fairly quickly - maybe only after a few loads.
The 280 AI and 30-06 AI are essentially identical in performance - get one, but no need for both.
The 25-06 AI is over bore and not much of an improvement over the 257 Roberts AI.
Of this group, the 257 Roberts AI is probably the best - just about perfect bore for the .25 caliber - that is, given modern powders.
Actually, the 280 AI is just about perfect bore for 7 mm caliber - the 7 mm Rem Mag and equivalents are all over bore, in my opinion.
The 30-06 AI is under bore for .308 caliber - I believe the 30-338 is just about perfect bore for 30 caliber - that is, until slower burning high-energy powders are developed. (I find that Reloader 25 is the best high-energy slow burner currently out there. I've tried slower burning powders, such as H870, Ramshot Magnum, Norma MRP-2, but they don't seem to have the energy content of R25.)
Summary: If you want to go Ackley Improved, I'd suggest the 257 Roberts AI and the 280 AI.0 -
while P.O. advertised his a.i. chamberings as having more velocity than standard chamberings please note A.I.U.'s loading for the .30/06 above. these loadings are much above saami spec's. and while safe in his rifle they may not be in others. one of the reasons most wildcats can get more velocity than a standard chambering is that there is no pressure 'red line' established for them. One local reloader justs keeps on adding powder untill the primers fall out, then backs off a grain or two (I do NOT go to the range with him). I believe the saami spec's for the .30/06 are about 48,000 cup, and for the .270 win. about 52,000 cup. Same case, same type rifles but almost 10% less pressure, guess which one looks better on paper. 0 -
The 270 of course!!
"What you do ultimately means nothing, and you could be replaced tomorrow by the first passing cretin." Corinne Maier0 -
I find them to be very proficient performers for the amount of powder they use compared to magnums. I also will agree with nononsense that they do not show pressure signs like the parent case did. I have run a 6.5-06AI with 140gr a-max pills up to 3208FPS in a 26" barrel and have not seen the first hint of pressure,..this does not mean that it is not there. I know 3200fps is way too high for that barrel and bullet weight in that chambering, so pressure is obviously too high even though I have had no warning signs.
I am a fan of the AI's as I have 3 (280AI, 6.5-06AI, and at the gunsmith currently is the 6.5x55AI)
why chase the game when the bullet can get em from here?....
Got Balistics?0 -
Hello If you come to Louisville Feb 26-27 gun show I will bring my 2 1959 Parker O Ackley books and you can and you can read them for a bedtime story "PRAISE THE HARDBALL GUN" 0 -
Check out auction #28874340. Remington 700 in 22-250 Ackley. Do you think this gun could be as accurate as seller states? Weighs almost 50 lbs with packed hard case? Would that put the gun by itself weighing 35-40 lbs? I'm not a competition shooter, but I sure would like to see a gun actually shoot that accurately. Of course, I know it's not just the gun but also the shooter. 0 -
Accuracy is the ability to repeat the aspects of a shot as closely to identical as possible. This means the shooter must do things exactly the same, the ammunition must be as uniform are possible and it's fit in the chamber is such that each cartridge sits as nearly the same as the othere rounds as possible, and the rifle and it's oscillations are as nearly identical as possible for each shot. As such you can see that while the rifle is an important part of accuracy, it is by no means the only aspect of the accuracy equation. 0 -
JustC: 32961761073435/comments/32961736390043
I find them to be very proficient performers for the amount of powder they use compared to magnums. I also will agree with nononsense that they do not show pressure signs like the parent case did. I have run a 6.5-06AI with 140gr a-max pills up to 3208FPS in a 26" barrel and have not seen the first hint of pressure,..this does not mean that it is not there. I know 3200fps is way too high for that barrel and bullet weight in that chambering, so pressure is obviously too high even though I have had no warning signs.
I am a fan of the AI's as I have 3 (280AI, 6.5-06AI, and at the gunsmith currently is the 6.5x55AI)
why chase the game when the bullet can get em from here?....
Got Balistics?What do you think the 6.5x55 is going to do ? I was thinking of that and or 243Ai
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What would the gain be and comparisons to 243 Ai
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