Thoughts on Ackley Improved cartrages

[MachIVshooter]

not even remotely the same as the Sierra data would imply.

Some random selections from Speer #13 (all max loads)

.300 H&H mag 165 gr.
IMR4831 71.0 Grs. 3185 FPS
IMR4350 69.0 Grs. 3185 FPS

7mm Rem Mag 175 gr.
IMR4831 59.0 Grs. 2,827 FPS
IMR4350 56.0 Grs. 2,789 FPS

.243 Win. 90 gr.
IMR4831 47.0 Grs. 3,107 FPS
IMR4350 46.0 Grs. 3,026 FPS

8x57 Mauser 200 gr.
IMR4831 54.0 Grs. 2,395 FPS
IMR4350 53.0 Grs. 2,432 FPS

I get what you're trying to say, and yes, 4350 is a little faster powder. Still, load data tends to be very close between the two, almost interchangeable with some cartridges/bullet weights.

I've run very heavy charges of both (think 97 grs. 4350 in my .375 RUM behind a 250 gr. BTSP and 99 grs. 4831 behind a 260 ballistic tip in the same), often exceeding published velocities in shorter barrels. Never had pressure issues beyond slightly flattened primers with either powder.

BTW, there is also a 2,900 FPS 300 gr. load for the RUM with either powder. 95.6 Grs. 4831, 93.5 Grs. 4350

 

[capreppy]

I've been giving this a lot of reading of late. I'm looking to rebarrel my Stevens 200 in .270 Win to either a .308 Win or a .260 Rem, but have been reading a fair amount regarding the .260AI. The .260AI has a lot of things going for it. You can fire regular .260 Rem brass in an AI chamber to fire form it and I like that.

 

[MachIVshooter]

I've been giving this a lot of reading of late. I'm looking to rebarrel my Stevens 200 in .270 Win to either a .308 Win or a .260 Rem, but have been reading a fair amount regarding the .260AI. The .260AI has a lot of things going for it. You can fire regular .260 Rem brass in an AI chamber to fire form it and I like that.

.260, like other .308 based cartridges, doesn't benefit much from improving. They already have minimal body taper and fairly sharp shoulders.

.308 vs. .308 AI:

Why not improve the .270 you already have? Or, since you're already working with a long action, do a 6.5-06 AI.........It'll out-perform the .260 by quite a bit.

 

[GooseGestapo]

All the discussion of the AI is nice, but remember, you're talking apples vs. oranges when comparing two different rifles, barrels, and lot#'s of powders.

All this makes a "ballistics manual" data comparison moot.

I've got a standard .257Roberts with the so called "3inch" chamber. For practical purposes it's data mirrors that of the .257Roberts RCBS "Improved" data that one of the manuals had data for back in the '80's when I built the rifle. It is an example of "one". A rule unto itself.

I had a .22Hornet AI back in the early '80's. It was a useless piece of junk as the chamber had been cut poorly rendering the rifle useless except for one shot with factory ammo. Fireformed brass was useless as it would split and collapse when sized. The chamber was cut too deeply and was out of round......

With the cost of new barrels plus cost of installation by a "qualified" gunsmith, I would just get a "used" Weatherby in either .257Wby (what I've got) or a .270wby if wanting something a little bigger. A used Weatherby Vanguard can be had for less than the cost of a new barrel on a Savage. (maybe even a new Vanguard for cost of a match grade barrel....).
Plus, you add the substantial cost of a set of dies for the new chamber, which can exceed $200.00, you can see that you could almost get a "magnum" rifle and buy a near lifetime supply of components for the cost of an "Ackley Improved".

I could see getting something like a .280AI that's a SAAMI listed cartridge in a new rifle, and reasonable priced dies, ect. But, I got a "deal" on a new, unfired .30 Herret barrel for a T/C Contender for $75.00. Then I found that a set of dies would set me back $200.00..... It's still unfired !!! I may have it reamed to .30/30 or such. Or just sell it to get my money back......
Don't even get me started on lot to lot variation on powders...... or barrels cut with different reamers....

If you are a gunsmith and can do the work yourself, including machining the dies like P.O.Ackley, then they make great experimental pieces... But if not, you'll be better off just getting a E.A.Brown barrel for your Savage action in the standard 6.5/06, and use an extra 2" bbl length to get the "extra" speed you "think" you need.
just my honest opinion... That, and I wouldn't use the Savage action as it lacks the "camming" of a Mauser, Rem. M700, or Win. Mod-70 to extract the case. Even getting "close" to peak operating pressures with the Savages I've had (.243 -(2), .30/06LH, .300RemUltMag) and extraction gets difficult due "stickiness" of the brass and at max loads needs a wooden block to extract the brass....

Plus that, and the fact that with Reloader 25 from my .257wby I'm seeing 3,700+fps with Max 100gr loads, and 3,650fps with a 2% reduction to a "working" load, that I can reload 5x+, and this from reformed 7mmRemMag cases that cost me nothing; I've got a $400 (including dies, scope) rig that I can get my money back on if needed..... With a AI, you're probably "stuck" with it.....Including the very expensive custom dies....

Several years back I got the hankering for something a little speedier. I got a used Savage M110 in .300RUM for $250 at a pawn shop because no one wanted it due to $$$ ammo. With some milsurp powders, I'm shooting it (what little I shoot it) for less than the cost of new components in a .30/30. Then I stumbled across the .257wby. Having a near lifetime supply of .257" bullets on hand and "all that surplus powder", I too picked up the .257 for $250.00......

Now, my desire for "something" faster has been assuaged, and I even "occasionally" hunt with them. Amazing though, that all the deer I've shot with them have been under 200yds (except one with the .300RUM @ 325yds... but still a "chip shot" for the '06....).
Even the little .257Robt. would have been"point blank" for that shot..... Hence it get's shot and hunted much, much more......

 

[quartermaster]

I am having a 25-06 AI rifle being built. It should be in my possesion within a month. I love the 25 cal, hence my handle on thr. I wanted to try the AIs due to all the reasons you mentioned in your initial post. I'm hoping to get almost 257 wby velocites out of it without dealing with all the freebore, which hopefully will make it easier to load for accuracy.

The new one is being built on a trued 700 action with an oversized recoil lug, Shilen 10" twist #5 SS 26" barrel, bedded in a laminated stock, and a Jewell trigger. It has a tight chamber, so I will be slightly turning necks. Hopefully the twist will be fast enough for 115-120 gr heads. Respectable authorities say it will be, although Shilen says I need a 9"

I am subscribing to this post to post my results, likes and dislikes when I get going on it.

I may start a thread, even though it has probably been beaten to death, on the fireforming process. I am hoping to be able to work up a load for it during that process, but who knows if it will be the optimum load for the second shooting. Part of me wants to try the fire forming process with the pistol powder and cream of wheat process and the other part of me wants to jam the bullets and shoot. I have 100 Norma brass to get started with, but can't decide which route to go. I'm leaning towards the latter.

Sorry to get off the original subject of this post Kachok. I am excited about getting this rifle and I guess it shows. If it works out I will consider another AI being made from an action of one of my other duplicate calibers.

 

[helotaxi]

Nice thing about an actual improved cartridge is that jamming into the lands isn't required to control headspace while fire-forming.

 

[Coltdriver]

In his day Parker Ackley was definitely on to something when he created the first improved rounds.

I have his books and they make for great reading.

And I have a .243AI.

But given the powder/bullet/chambering improvements we have seen in the last 10 years I wonder if there is any real advantage to an AI chambering? They do look cool.

I have my eye on a .270 WSM. Same sort of concept with the fat cartridge.

I have not found the very highest velocity loadings to be the most accurate also. Once in a great while that happens or you find a "node" up near the limit where it works out.

 

[MachIVshooter]

The new one is being built on a trued 700 action with an oversized recoil lug, Shilen 10" twist #5 SS 26" barrel, bedded in a laminated stock, and a Jewell trigger. It has a tight chamber, so I will be slightly turning necks. Hopefully the twist will be fast enough for 115-120 gr heads. Respectable authorities say it will be, although Shilen says I need a 9"

That should be quite a shooter! And 1:10" twist is standard for .25-06, so you shuld be fine unless you start making custom 130 gr. + pills.

 

[Slamfire]

Don’t forget less bolt thrust as the cartridge tends to grab the chamber walls harder since there is little to no taper.

P.O Ackley was selling snake oil.

Cases don’t act as wedges or inclines. Unfortunately they stretch. They don’t carry load, or should not carry load, they are simply a gas seal.

At the time ole PO was selling his Ackley improved (AI) cartridges, he was blowing out the shoulders, straightening the case, to increase powder capacity and raising pressures. It is obvious that ole PO was taking flak from folks who were claiming that his high pressure cartridges were overstressing the action.

This would be an interesting side topic, but based on the cartridge taper advice found in my design books, straight cases are not an ideal form. They don’t steer well and they don’t retract well. If the mechanism does not cycle well, if case sticking is a constant problem, if feed geometry is too fickle, the mechanism will be a failure.

P.O Ackley cartridges are very interesting and P.O’s test of a straight sided cartridge holding pressure without a breech block has been duplicated. The tester swabbed the chamber out with alcohol swabs between shots. The Ackley cartridge held. However the other cartridges, such as the 30-30, 35 Remington, blew out of the breech at 1900 fps. A 150 grain cartridge case flying at 1900 fps will go through both sides of most people's skulls.

Ackley was taking heat because he was getting high velocities from his improved cartridges, cartridges which were being used in actions not designed for the things. P.O. wanted to show that his speedy cartridges did not increase bolt thrust, and infact as a result of his experiments, claimed they actually reduced bolt thrust. Which was bogus as heck as these improved cartridges actually ran at higher pressures. Higher pressures increases bolt thrust, it does not lessen it. P.O got higher velocities through higher pressures.

Read carefully Boatright’s papers one of which he shows how a 308 case, in a clean chamber, can lock in and hold pressures by itself up to 25K psia.

Go to Jim Boatright’s web page.

http://www.thewellguidedbullet.com/

Look for yielding of the brass case in these studies

http://www.thewellguidedbullet.com/mechanical_studies.htm

However once pressures go above 25K psia, Boatwright shows the brass case stretches and if not supported, the case head will blow off.

Regardless of taper, and all that mystical mojo, cases are made out of brass and will stretch. There may be bolt load reduction due to friction and stretching but it is inconsistent and not to be relied on in any way.

Apparently the standard 30-30 is strong enough not to lose its case head without the AI taper.

http://gunsmithtalk.wordpress.com/2008/08/19/ackley-bolt-thrust-tests/

I have not seen actual pressure test data verifying his claims of more velocity with less bolt thrust. If you notice, P.O. Ackley never conducted his test with a 30-06 or a similar high pressure cartridge. I am certain those would have blown right out the back of his lug less rifle. Ackley and others did not conduct sensitivity tests, varying chamber finish, (chrome for example), powders, primers, or much of anything else. I totally disagree with the implicit conclusion that Ackley and others have drawn, which is if Ackley improved cartridge reduces bolt thrust, a user can just pour the coal into the cartridge and let fly. Ole P.O. was interested in promoting his cartridges, found a “one off” and left a very misleading legacy in terms of case friction, load, and chamber roughness.

 

[35 Whelen]

P.O Ackley was selling snake oil.

Cases don’t act as wedges or inclines. Unfortunately they stretch. They don’t carry load, or should not carry load, they are simply a gas seal.

At the time ole PO was selling his Ackley improved (AI) cartridges, he was blowing out the shoulders, straightening the case, to increase powder capacity and raising pressures. It is obvious that ole PO was taking flak from folks who were claiming that his high pressure cartridges were overstressing the action.

This would be an interesting side topic, but based on the cartridge taper advice found in my design books, straight cases are not an ideal form. They don’t steer well and they don’t retract well. If the mechanism does not cycle well, if case sticking is a constant problem, if feed geometry is too fickle, the mechanism will be a failure.

P.O Ackley cartridges are very interesting and P.O’s test of a straight sided cartridge holding pressure without a breech block has been duplicated. The tester swabbed the chamber out with alcohol swabs between shots. The Ackley cartridge held. However the other cartridges, such as the 30-30, 35 Remington, blew out of the breech at 1900 fps. A 150 grain cartridge case flying at 1900 fps will go through both sides of most people's skulls.

Ackley was taking heat because he was getting high velocities from his improved cartridges, cartridges which were being used in actions not designed for the things. P.O. wanted to show that his speedy cartridges did not increase bolt thrust, and infact as a result of his experiments, claimed they actually reduced bolt thrust. Which was bogus as heck as these improved cartridges actually ran at higher pressures. Higher pressures increases bolt thrust, it does not lessen it. P.O got higher velocities through higher pressures.

Read carefully Boatright’s papers one of which he shows how a 308 case, in a clean chamber, can lock in and hold pressures by itself up to 25K psia.

Go to Jim Boatright’s web page.

http://www.thewellguidedbullet.com/

Look for yielding of the brass case in these studies

http://www.thewellguidedbullet.com/mechanical_studies.htm

However once pressures go above 25K psia, Boatwright shows the brass case stretches and if not supported, the case head will blow off.

Regardless of taper, and all that mystical mojo, cases are made out of brass and will stretch. There may be bolt load reduction due to friction and stretching but it is inconsistent and not to be relied on in any way.

Apparently the standard 30-30 is strong enough not to lose its case head without the AI taper.

http://gunsmithtalk.wordpress.com/2008/08/19/ackley-bolt-thrust-tests/

I have not seen actual pressure test data verifying his claims of more velocity with less bolt thrust. If you notice, P.O. Ackley never conducted his test with a 30-06 or a similar high pressure cartridge. I am certain those would have blown right out the back of his lug less rifle. Ackley and others did not conduct sensitivity tests, varying chamber finish, (chrome for example), powders, primers, or much of anything else. I totally disagree with the implicit conclusion that Ackley and others have drawn, which is if Ackley improved cartridge reduces bolt thrust, a user can just pour the coal into the cartridge and let fly. Ole P.O. was interested in promoting his cartridges, found a “one off” and left a very misleading legacy in terms of case friction, load, and chamber roughness.

I have read both of Ackley's handbooks and I don't recall seeing any pressure data on his AI cartridges (please correct me if I'm wrong, as it's been 20+ years), so your blanket statement :"...these improved cartridges actually ran at higher pressures." is at best a guess. Cartridges, by design, don't run at higher pressures as though it's come uncontrollable factor. As we all know, higher than normal pressures are most always attributable to loading practices.

The primary goal of reducing case taper and increasing shoulder angle is simple; to increase case capacity thereby increasing velocity potential.

Evidently all his experimenting wasn't without merit as todays newer cartridges, oddly enough, resemble AI cartridges. The WMS line, 22 & 6mm PPC, etc. When's the last time one of the major ammunition manufacturers introduced a cartridge with steep body taper and a shallow, sloping shoulder? I wou;d say somewhere around 1925 when Holland & Holland introduce the 300 H&H.

35W

 

[quartermaster]

I don't feel that case stretching and failure is a problem after you get past the fireforming procedure. I would expect that most people would just neck size or set the shoulder back .001 or .002 elimimating excessive expansion from that point and on.

On the other hand, I'm not sure about pressure issues. Personally when I fireform my 25-06 cases into the AI chamber I have intentions of starting at a bit less than max loads for the parent chamber and doing whatever is necessary to fully form the case. I would expect with the second loading that pressure could be kept in check utilizing powder choice and charge accompanied with primer selection.

I also considered the 6.5-06 before making my selection. I just love the 25's. Good luck with whatever you decide on and let us know how it works out for you

This will be my first dealing with an AI cartridge. I'm looking forward to the experience and figure on taking my time and carefully working up to where I hope to get. Time will tell.

 

[Slamfire]

I have read both of Ackley's handbooks and I don't recall seeing any pressure data on his AI cartridges (please correct me if I'm wrong, as it's been 20+ years), so your blanket statement :"...these improved cartridges actually ran at higher pressures." is at best a guess. . As we all know, higher than normal pressures are most always attributable to loading practices

.


There is not any pressure data in PO's book. There is load data, and if you look at the load data for standard cartridges, the maximum are several grains over today's measured data.

I have not seen pressure data on the Ackley improved. I look at the increased velocities ole PO got and don't see how he did it without increased pressures.

Cartridges, by design, don't run at higher pressures as though it's come uncontrollable factor

Since PO did not use pressure gages in the development of his improved cartridges, then what did he use in "designing" his cartridge?

 

[35 Whelen]

.


There is not any pressure data in PO's book. There is load data, and if you look at the load data for standard cartridges, the maximum are several grains over today's measured data.

I have not seen pressure data on the Ackley improved. I look at the increased velocities ole PO got and don't see how he did it without increased pressures.



Since PO did not use pressure gages in the development of his improved cartridges, then what did he use in "designing" his cartridge?

Yes, they probably are over todays measured data. I have a few older loading manuals including a Hornady from the '70's. Their data likewise is well over todays data. I don't pretend to know why...different powder formulas? Fear of lawsuits? Who knows?

You stated:

Ackley was taking heat because he was getting high velocities from his improved cartridges, cartridges which were being used in actions not designed for the things. P.O. wanted to show that his speedy cartridges did not increase bolt thrust, and infact as a result of his experiments, claimed they actually reduced bolt thrust. Which was bogus as heck as these improved cartridges actually ran at higher pressures. Higher pressures increases bolt thrust, it does not lessen it. P.O got higher velocities through higher pressures.

First of all, please state your sources regarding Ackley "taking heat" because he was getting high velocities from his improved cartridges. Higher velocities were the primary goal of improved cartridges. You do understand the principle of improved cartridges, don't you? If not, let me explain:

The principle of improved cartridges is to take a given case and increase its internal capacity thus increasing its powder capacity which in turn increases the velocity potential over that of the standard case, NOT to have a new cartridge that runs at higher pressures. Think of the 257 roberts and the 25-06. Loaded with optimal powders for each cartridge, to identical pressures with identical bullets, the 25-06 will provide a higher velocity than the 257 Roberts...and so it is with the 257 Roberts and the 257 AI. If it weren't so, the improved cartridges would be worthless rather than alive and well 60-some years after their inception.
Bolt thrust blah, blah aside, if the improved cartridges ran at higher pressures, it was/is because they were LOADED to higher pressures...not because the improved case somehow magically created higher pressures. You state in the quote above "...these improved cartridges actually ran at higher pressures." then concede that Ackley's handbooks had no pressure data. So, how do you know they ran at higher pressures?

As one who's loaded the 257 AI since the '80's, I can tell you with 100% certainty that standard loads in the improved chamber actually created LOWER chamber pressure. I know this because I fire-formed quite a few 257 AI cases by simply firing a 257 Roberts factory load in the improved chamber. Measured MV's were substantially lower (hence indicating lower pressures) than advertised MV's.

35W

 

[lefteyedom]

Had affordable chronographs been available to the public in Mr Ackley (or Gibbs) day A.I cartridges would not have the following they do today.Now with chrony anyone can test the (wild?) claims of gun writers, reloading manuals and cartridge designers.

The basic designs of Mr Ackley cartridge are not bad.

Most A.I. do not delver enough performance improvement to justify the cost. What is the real value of 100 to 200 extra FPS if you are already making 2600-2800 FPS?

A range finder and a better scope would likely be a better use of one money.

All that said/// I would like to build a 6.5/06 AI...

 

[35 Whelen]

Had affordable chronographs been available to the public in Mr Ackley (or Gibbs) day A.I cartridges would not have the following they do today.Now with chrony anyone can test the (wild?) claims of gun writers, reloading manuals and cartridge designers.

Exactly. one of the things that made the 257AI so appealling was it was a vast improvement over the factory 257 Roberts loads because the factory loads were loaded to low pressures. Loaded to equal pressures, I doubt the 257AI has much more than a 100-150 fps improvement over the 257 Rob.

35W

 

[helotaxi]

Yes, they probably are over todays measured data. I have a few older loading manuals including a Hornady from the '70's. Their data likewise is well over todays data. I don't pretend to know why...different powder formulas? Fear of lawsuits? Who knows?

Better measuring technology. The old loads were developed using copper crusher test barrels that are not an accurate measure of dynamic pressure and pressure changes. With the advent and availability of modern strain gauges and piezoelectric pressure barrels with high speed capture measured in the microseconds, load developer quickly realized that the previously published loads were often grossly beyond accepted max pressure levels.

 

[Coal Dragger]

I have a .280AI chambered in a Cooper M52, and so far it has been an excellent combination. Accuracy is superb, and the claimed velocities in the Nosler Manual seem to be pretty accurate within 25-50fps, at any rate bullets hit where they should plugging the values into a ballistics program. I am very pleased with the rifle and cartridge combination, and have noticed no problems at all with feeding or any other issues.

 

[quartermaster]

CD

"Accuracy is superb, and the claimed velocities in the Nosler Manual seem to be pretty accurate within 25-50fps, "

Sorry, I haven't figured out to do the quote box yet.

I always wondered about the velocity in the Nosler manual for the .280AI, as it always seemed to be quite a bit higher than other soures of data. I figured that they beefed up their velocities a bit to promote their rifle.

It's good to know that it's close. It may influence a future decision that I have been thinking about.

I will agree that there is not a great velocity increase in some of the AI's, but there are a select few which will gain a couple of hundred feet/second. But in considering the cost, you have to think about the fact that if you are going to go the route of a custom rifle, there really is no additional cost involved for an AI over a std cartridge. Granted you may have a bit more time involved with fire forming and may use a touch more powder loading, but even if the gain may be only 100 FPS, why not go for it? You also have the benefits which Kachok mentioned in the original post.

 

[Coal Dragger]

I can't speak for all the AI cartridges, but the .280AI is probably just falling into about the perfect case capacity for a .284/7mm bore. That magic area where you can still burn all the powder efficiently, but you are pretty much right at the limit of how much you can burn at the highest efficiency rate. Cartridges like the regular .280 Remington, and the 7mm-08 are still very efficient, but could actually use more powder for the bore diameter, and the 7mm Remington Magnum can burn more powder and get a little bit more velocity but the returns for burning the extra powder diminish and continue to the more powder you throw at the bore size.

So for 7mm/.284 diameter bores cartridges like the .280AI, 7mm Remington SAUM, and 7mm WSM are pretty much in that sweet spot.

As you noted in a custom rifle or semi-custom rifle there is not much you are compromising with an AI cartridge, other than the time involved in forming brass, and the higher cost of custom dies. In the case of the .280AI there is no sacrifice since factory brass is both excellent and available, and so is ammo. I think I read somewhere that Kimber is chambering rifles in .280AI now, so perhaps it will become a bit more common. It would be nice if another ammo maker would start offering loaded rounds and brass too, but for now Nosler components are nothing to scoff at.

 

[CaptainCrossman]

P.O Ackley was selling snake oil.

Cases don’t act as wedges or inclines. Unfortunately they stretch. They don’t carry load, or should not carry load, they are simply a gas seal.

At the time ole PO was selling his Ackley improved (AI) cartridges, he was blowing out the shoulders, straightening the case, to increase powder capacity and raising pressures. It is obvious that ole PO was taking flak from folks who were claiming that his high pressure cartridges were overstressing the action.

This would be an interesting side topic, but based on the cartridge taper advice found in my design books, straight cases are not an ideal form. They don’t steer well and they don’t retract well. If the mechanism does not cycle well, if case sticking is a constant problem, if feed geometry is too fickle, the mechanism will be a failure.

P.O Ackley cartridges are very interesting and P.O’s test of a straight sided cartridge holding pressure without a breech block has been duplicated. The tester swabbed the chamber out with alcohol swabs between shots. The Ackley cartridge held. However the other cartridges, such as the 30-30, 35 Remington, blew out of the breech at 1900 fps. A 150 grain cartridge case flying at 1900 fps will go through both sides of most people's skulls.

Ackley was taking heat because he was getting high velocities from his improved cartridges, cartridges which were being used in actions not designed for the things. P.O. wanted to show that his speedy cartridges did not increase bolt thrust, and infact as a result of his experiments, claimed they actually reduced bolt thrust. Which was bogus as heck as these improved cartridges actually ran at higher pressures. Higher pressures increases bolt thrust, it does not lessen it. P.O got higher velocities through higher pressures.

Read carefully Boatright’s papers one of which he shows how a 308 case, in a clean chamber, can lock in and hold pressures by itself up to 25K psia.

Go to Jim Boatright’s web page.

http://www.thewellguidedbullet.com/

Look for yielding of the brass case in these studies

http://www.thewellguidedbullet.com/mechanical_studies.htm

However once pressures go above 25K psia, Boatwright shows the brass case stretches and if not supported, the case head will blow off.

Regardless of taper, and all that mystical mojo, cases are made out of brass and will stretch. There may be bolt load reduction due to friction and stretching but it is inconsistent and not to be relied on in any way.

Apparently the standard 30-30 is strong enough not to lose its case head without the AI taper.

http://gunsmithtalk.wordpress.com/2008/08/19/ackley-bolt-thrust-tests/

I have not seen actual pressure test data verifying his claims of more velocity with less bolt thrust. If you notice, P.O. Ackley never conducted his test with a 30-06 or a similar high pressure cartridge. I am certain those would have blown right out the back of his lug less rifle. Ackley and others did not conduct sensitivity tests, varying chamber finish, (chrome for example), powders, primers, or much of anything else. I totally disagree with the implicit conclusion that Ackley and others have drawn, which is if Ackley improved cartridge reduces bolt thrust, a user can just pour the coal into the cartridge and let fly. Ole P.O. was interested in promoting his cartridges, found a “one off” and left a very misleading legacy in terms of case friction, load, and chamber roughness.

this is an old thread, but worth reviving- there's lot more to it than what you are proposing here.

if you take a standard cartridge, fire form the case larger, and reload it with the same weight bullet and powder charge, the pressure will go DOWN. not up.

you will have to ADD powder, just to equal the pressure it had with a smaller case and less powder at the starting point.

the gain is made, when you add just a little more beyond the equalization point.

some wildcats did not have enough additional case capacity after being "improved" or blown out, to make it worthwhile doing.

others had quite a bit of additional capacity, and these were the most successful.

and a few others were already maxed out and "overbore" in standard form, that adding excess powder capacity beyond that point, made barrel life an issue. Ackley admitted his own 25-06AI and 270AI were not recommended for this reason.

another overlooked design parameter is this- after creating a very high chamber pressure, it can then be greatly tamed down, by using freebore ahead of the chamber. this is why a factory Weatherby Mk V. action can survive having a stuck bullet in the barrel, and firing another one behind it, without blowing up. both bullets exit the barrel, and the brass ejects with the bolt and hand pressure. freebore greatly reduces pressure of super high pressure magnums in such actions.

so when looking over standard cartridges to wildcat, some had more potential than others, because they had sloping shoulders and were a little underloaded to begin with. notable success stories were the 250-3000 AI, 30-06 AI, 257 AI, 30-30 AI.

IMHO the 2 most promising and attractive are the 30-30 AI in a Winchester, Savage, or Marlin lever action, where you could gain 300 fps.

or the 30-06 AI in a bolt action, where you could equal a factory mild 300 H&H magnum load.

if anything is snake oil or misleading, it's the idea a 24 or 25 caliber is any good for brush hunting, esp. here in the NE USA. the guys who raved about the 24's and 25's were hunting out in the Midwest and West, there the "brush" is grass about 6" high, and they can see for miles with binoculars.

we can barely see 150 yards in the woods where we hunt. If you are that far away from another hunter, you don't even know he's there even with fluorescent orange clothing. and the furthest we can actually shoot at deer is about 100 yards.

you need a 30 cal or better to hunt brush here, and preferably a 35 caliber. the deer head straight for the brush and then all you hit is lumber.

in this respect, it's really hard to beat the old 35 Remington here. it already has a mostly straight case, and only as much powder as you need, to kill a deer at 100 yards in heavy brush. it's improved and "blown out" right from the factory. a 35 rem in a Marlin 336 is all one really needs here in the woods.

 

[Slamfire]

if you take a standard cartridge, fire form the case larger, and reload it with the same weight bullet and powder charge, the pressure will go DOWN. not up.

you will have to ADD powder, just to equal the pressure it had with a smaller case and less powder at the starting point.

the gain is made, when you add just a little more beyond the equalization point.

some wildcats did not have enough additional case capacity after being "improved" or blown out, to make it worthwhile doing.

others had quite a bit of additional capacity, and these were the most successful.

Sure sounds nice, but what was Ackley doing? I don't remember any pressure tested data in Ackley's Handbook, all he printed was velocity data.

Savants on other forums give out a rule of thumb that a 40% increase in case volume provides a 10% velocity increase, implicit is the assumption that this is isobaric. This may be a crude rule of thumb, and I have done nothing to verify this. Below are comparisons of Ackley's published data compared to pressure tested data.

49th edition of Lyman Handbook, the max load of a standard 30-30 with a 150 grain bullet and using 28 grs IMR 3031, the velocity is 2145 with a pressure of 38,000 cup.

In Ackley’s own handbook, the maximum load for a 30-30 AI for a 150 grain bullet using IMR 3031 is 38 grains for a velocity of 2700 fps.

From web data, the case capacity of the 30-30 Ackley vs the unImproved Winchester parent differ by 5% http://www.gmdr.com/lever/3030atext.htm yet here you have Ackley stuffing in 10 additional grains of powder and claiming a velocity increase of 125% over the standard 30-30.

The only way to get those sort of velocities through incredibly high pressures.


If you go to your 1957 Gun Digest, factory ballistics for the Winchester 180 grain Super Speed 30-06 is 2700 fps. Modern reloading data shows you can push a 180 Barnes with 55.7 grs IMR 4350 to 2685 fps, in close agreement with older factory data.

Ackley’s handbook gives reloading data of 61 grains IMR 4350 with a 180 grain bullet for a velocity of 3053 fps.

Noslers shows a max load for the 30-06AI of 56.5 grs IMR 4350 with a 180 gr bullet at 2835.

For the 30-06AI Ackley is putting 5.3 additional grains of powder in the case and claiming a velocity increase of 113% over the parent cartridge. His data is pushing bullets 218 fps faster than modern pressure tested ammunition of the same case.

The only way to do this is through incredibly high pressures.

Clearly anyone now, or then, who had access to a ballistic lab or even crude rules of thumb would be able to say that the only way Ackley was able to achieve those high velocities was through extremely high pressures.

Ackley sold so much snake oil that the shooting community is still swimming in it up to their chins. Authority figures who are wrong create enormous damage: no one challenges them when they are alive, and when they are dead, their acolytes still believe their rubbish.

Fans of AI are welcome to own, praise, worship their cartridges and its creator. I am going to take a different path.

 

[justin22885]

the "improved" aspect is highly subjective, i see less taper and a steeper shoulder, looks like something that would function rather poorly in a semi and performance gains seem generally negligible

 

[Bart B.]

99 plus of all the comparisons of a given caliber cartridge A to B does not use the same pressure, barrel length, bore, and groove diameters. Nor do they use the same pressure and velocity measuring system and technique for each. Therefore, by their nature, they cannot be realistically compared.

SAAMI's specs for all the cartridges are probably the best to compare those of the same caliber (bore diameter). Wildcat versions rarely, if ever use the same tools and barrel criteria as SAAMI does.

 

[alientrainwreck]

I have a 336 30-30AI and a rem700 30-06AI both have 40 degree shoulders and both are extremely accurate rifles. I have had zero problems with both. I have found that superformance powder with the 06AI have made it worthwhile and leverlution for the 30-30AI with Ftx or monoflex bullets really shine.

 

[T.R.]

My hunting buddy has a Remington 700 chambered for 280 AI. He approaches 7mm MAG ballistics with his handloads yet recoil isn't too bad at all. We hunted elk together in Wyoming a few years back. I downed a medium sized 4 X 4 but he nailed a really big 5 X 6 bull. The animal was no match for his hand loaded Nosler Partition bullet.

Another buddy has a customized Savage 219 chambered for 30-30 AI. With its 26 inch barrel and careful hand loads he can replicate 300 Savage ballistics. This is no small feat for a so-called brush cartridge!

My impression is that AI cartridges are not for everyone but confident hand loaders will be pleased with results.

TR