Could someone point me to a site talking about AI cartidges. Whats the deal with them? Just a shoulder change? I was looking at a 25-06 AI and thought it might be a fun round to load for.

An "improved" cartridge fireforms a factory round into a larger chamber. The change is to increase the capacity of the case and sometimes to make the sidewalls straighter and the shoulder sharper.

Usually the barrel must be removed from the action and rechambered deep enough to remove the orginal shoulder. This necessitates setting the barrel back a thread or more.

The negatives are primarily just money.

I don't know of any web site that specializes with the ackley improved variants. In regards to those based on the -06 case, the shoulder is sharpened to 40 degrees, and the body is reduced in taper, to where it is nearly straight.

Having done a rather extensive bout of loadwork with a 35 whelen AI, I'll give you all the downsides. The brass is more work to make, and you can easily get excessive headspace in the brass, and subsequent case head seperations. The case increase in capacity is at most 5%.

Despite all the claims, the velocity increases sited by Ackley fans are due almost entirely from running at higher pressures, not the modest increase in case capacity. Honestly, a 5% increase in case capacity will provide a 1 1/2% increase in velocities at the same pressure.

Dies are more exspensive, your guns re-sale drops, your rounds will not feed as smoothly out of the magazine w/o modifications to the feed rails, and you'll likely loose one round of capacity in your mag.

If you want a bigger case, then go for one that has a noteable increase in volume, such as the 257 Wetherby.

Years ago, when P.O.Ackley was working out of his garage in Salt Lake City, I visited him. We talked extensively about his "improved" cartridges. The jist of the conversation was that in reality two of his "improved" cartridges worked very well and the rest were really just marginal. Take a look at Ackley's data for the 7x57AI and the .257AI. I have hunted here in Alaska for 34 years with my 7x57AI as my caribou and sheep rifle. My rechambered Ruger{hate to admit it. ;^) } gets 2950 f/s with the 160 Nosler and almost 3100 f/s with the 140 X. I'm still amazed at how close Ackley's velocity data was to my Oehler 35P for those days. That's been my experience. Craig

Ackley's two-volume "Handbook for Shooters and Reloaders" has a wealth of information, including discussions of all the Ackley Improved cartridges. In most cases, he says the improvement is marginal, and at the expense of faster barrel erosion, more recoil, more expense and more difficulty in finding a good load.

However, the reason is that the people who want super velocity often started with an overbore cartridge (too much powder capacity for the bore size) and wanted to keep increasing velocity. It is a case of dimishing returns, where it takes more and more powder to get smaller and smaller increases in velocity.

The .25-06 is already way overbore, and further increases in capacity provide very small increases in velocity. There is a good chance that even a slightly used .25-06 improved will have a worn out barrel.

More efficient cartridges, such as the 7x57 and .375 H&H, show remarkable increases in velocity, since they are starting with an "underbore" capacity.

HEY'
I have a 65-06 Imp since June.I use 25-06 brass,and just set up the 6.5 die to the new shoulder junction,and fire form.Not much trouble at all.It's getting quite popular with competition shooters.They favor the 6.5-.284,a bit over the 06 case.Both are excellent.
1geejay
www.shooting-hunting.com

Paul H - nice to hear somebody with first-hand experience. While I think your representations are a bit grim "flavoured", in large part I would agree with the cautionary tenor.

KLN - I think you are confusing Ackley's comments regarding "magnum" cartridges with the "Ackley Improved". I find NO references or comments in either book to

quote:

---

barrel erosion, more recoil, more expense and more difficulty in finding a good load

---

when he was discussing his "improvements". On the contrary, here is his quote about the .257 Roberts Improved (Ackley):

quote:

---

It is a relativley efficient cartridge, flexible and comes close to the mythical "all around cartridge". It is considered to be about the maximum capacity for the .25 bore and still produce satisfactory performance and good barrel life. Like other improved cartridges, rifles chambered for it will still accept factory ammunition which appeals to many shooters who do not whish to re-load all of thier ammunition. It is always an advantage in a pinch to be able to purchase a box of cartridges over the counter. The Improved .257 can be readily recommended.

---

in: Handbook for Shooters and Reloaders, Volume I, page 331.

His praises of the .25-06 Improved are less glowing, but agian, I find NO comments BY ACKLEY badmouthing his "Improved" cartridges. Onthe other hand, his books are replete with castigations of "over-bore" magnums.

For me, I like the .257 AI I have, and I have had none of the problems like reduced magazine capacity, difficulty forming brass, expensive dies (I fire form and neck resize only) or reduced resale, mentioned by Paul H. However, his comments are the first one's I have ever seen that were 1) based on first-hand knowledge, and 2) essentially negative. It's always good to see both sides of a coin.

Paul

Here is an excerpt directly from Ackley's book which goes to both Paul H's and KLN's comments"



[ 09-12-2002, 22:20: Message edited by: gitano ]

Thanks guys. You all have about talked me out of a rifle. There is guy that has a 25-06 AI for sale with alot of work from a brand new barrel, refinished stock on a Long Action remington 700 for around $400. But he wants a very cheap price due to he is haveing a hard time selling due to the AI. where did you find these books?

In general the improved cartridges are not a big problem and can add to the fun of shooting. But they are really not necessary in most cases. Some of it is just to see what will happen and have something different.

In the case of the 35 Whelan which has a very small and "weak" shoulder for headspacing I would think that a correctly done one would improve ultimate headspacing. But the cartridges must be fireformed with care.

In the case of the .22 Kilbourn Hornet it is a big improvment I read. In the case of my .219 Improved Zipper the same. That is an outstanding .22 CF. I have had no problems whatsoever either with my 30/06 Improved but by the time I got it I had almost seen it all and it was not as big a thrill as your first one might be.

A while back I had a custom rifle made up in .375 H&H Improved. That is a very good cartridge but now that the RUM cases are available I would never do that again.

An improved chamber done right is something that anyone could deal with. It's not a tiger by the tail like a Gibbs cartridge for instance.

I might buy a 25/06 Improved at a low price. But I would not make one. The 25/06 has enough capacity as is and the standard case has no other problems to solve either.

The way it was explained to me by my gunsmith (before I built a .338-06AI) is this:

Improving a case is essentially adding 2" of barrel. Nothing more. This can be used for two things. First, to maintain a cartridge's performance in a shorter barrel. Or, boost the performance close to "magnum" levels in a barrel of standard legnth.

Just something else to think about that I thought was practical advise.

gitano:

Suggest you read the chapter on bore capacity, Vol 1, p165.

In his discussion of the 25-06 Ackley Improved, Ackley says it is "...critical (meaning difficult to find a good load for) and hard on barrels...", and "...not recommended...".

In his discussion of the standard .25-06, he says it is , "...more satisfactory in the long run than the 'improved' version."

Even with the .270 Winchester Ackley Improved, which is less over-bore than the 25-06 Improved, he says, "Since the original .270 is over bore capacity, little improvement can be expected...." and "...due to its relative inefficiency, it is not recommended...."

Seems fairly clear to me.

In the "under-bore" capacity cartridges, such as the ones you selected for illustration, and my .375 H&H Ackley Improved, significant improvement is the norm.

KLN

I really don't want to belabor the point, but I'll clarify a little.

First the "Bore Capacity" chapter starting on page 165 of Volume I has only ONE SENTENCE regarding AI cases, and that sentice is IN PRAISE of the .270 AI. The ENTIRE REST of the chapter is devoted to various increases OTHER THAN THE AI ranging from fairly modest to absurd. NOWHERE in that chapter does he disparage or "play down" in ANY way the modificaion that bears his name. Nor does he allude to the AI modification as causing any of the negatives you listed in your reponse. Furthermore, he makes this SPECIFIC statement;

quote:

---

It has been found that the .257 Remeington case somewhat increased in capacity(emphasisi mine), is the ideal in every way for this popular caliber. If we insist on a belted case, for some resason, it should be shortened to a point where the cubic contents will equal that of the improved case. (Emphasis mine)

---

However, your statement was:

quote:

---

In most cases, he says the improvement is marginal, and at the expense of faster barrel erosion, more recoil, more expense and more difficulty in finding a good load.

---

(Emphasisi mine.)

Your statement was in [b]direct response to a question about AI cases, NOT magnums OR other OVERBORE capacity cases. Your chosen example, the 25-06 was overbore to start with, and so stated by Ackley.

It is a bit absurd to suggeest that Ackley, the most vocal opponent to "magnums" and other over-bore-capacity cartridges, would create a modification to cartridges that in general flew in the face of everything the said and wrote and apparently believed fervently in, AND THEN ENTHUSASTICALLY ATTACH HIS NAME TO IT.

The point was and remains, most BUT NOT ALL, AI cartridges perform "better", in some fashion. In many instances, the primary improvement was to reduce the "back thrust" caused by a case designed with a fairly steep taper. The improvement in velocity, however small, was "icing on the cake". In addition, the 40 degree shoulder was often a better headspacing reference for some of those early 20th century cartrides. Again this was addressed in the chapter you reference. Maybe YOU should read that chapter.

Finally, Ackley's "Improvement" is in fact the primary foundation upon which ALL of the currently fashionable "short Magnums" rest. Stubby, straight-sided, steep shouldered cases that REDUCE throat erosion (again specifically addressed in that chapter), exemplified and proto-typed by the AI case, are finally recognized as "better" for a variety of reasons.

In MOST applications, AI cases are "better" in some fashion if the case you start with is NOT OVER-BORE capacity to start with.

Hugs and Kisses,
Paul

Your question seems to be more - should I pass on this high quality rifle which is selling cheap because no one else wants to buy a AI caliber. I would tell you not to be afraid of AI calibers, as long as you are a reloader. While you can shoot factory rounds in an AI chamber it can only detract from accuracy. Plus, to fire form the casing the first time you want to seat out the bullet to engage the rifling, thus keeping the back of the case tight to the breech. The only added expense you have is the die, just neck size, and if you don't have this standard caliber size die, a AI die is only about $10 more. If you don't want to wear out barrels from having an overbore design - then just don't load to max, load to standard velocities. As far as I am concerned, my 6MM Rem AI is not a problem, and the brass does seem to last longer.

If you can get a good deal on an AI chambered rifle, and you know that it is a good rifle, ie well built, in good shape, shoots well, et all, then by all means jump on it.

The guy selling it has taken the depritiation hit, and you can enjoy the rifle, provided it is a good gun.

I would not intentionally build an AI gun again, as I think the detriments far outweigh the minor benefits. That said, I never turn down a good deal when it presents itself

As far as the 25-06 AI, I would take the sentiments about not finding good loads for it in the Ackley book with a grain of salt. There have been many new powders introdoced as of late, and the term "over-bore" is really moot with the selection of slow burning fuels.

Don't try and make a 257 Weatherby out of, that is where folks get in trouble thinking that that the AI chamber suddenly makes the -06 case capable of magnum performance at sane pressures. It doesn't, it just hides many of the traditional over pressure signs so folks unwittingly believe they can safely load up til the primers fall out, then back off a 1/2 gr.

Take the approach of using modern 25-06 data and powders, and adding a bit more fuel to gain 50-100 fps.

Hmmmmmmmmmmmm . . .

I have a Rem. 700 PSS in .223 AI. Brass lasts forever because the steeper shoulder keeps it from flowing into the neck. Accuracy with standard ammo is fine. Velocity with AI loads is sigificantly faster. Bore erosion is lessened because the steeper shoulder burns more of the powder in the case rather than in the throat of the barrel.

Why doesn't some commercial mfg just produce this sort of brass OTC ??? Because the dies to set up the neck would be too complex.

One the brass is sized for the bore in AI, only neck sizing is required. No need for "Ackley" dies in most cases. The whole concept of the AI is that the brass is fire formed in the bore, and that the bore still accommodates standard loads/brass in the pre-improved caliber.

More on the web site/forum . . .

BC:

Sounds like you are making a wise decision. There are those who adhere to the "more is better" school of thought, and then there are the "effeciency" proponents.

One group thinks that every grain of powder that you can cram behind a bullet makes it better. (super ultra whammy boomers) Then there are those who believe that with a given bullet, a couple of hundred fps does not make any noticeble difference in the field.

The "boomers" ridicule the moderates by saying... "so a 30-30 is as good as a 300 ultra??"... yeah right!!!

The moderates ridicule the boomers by saying..."so 2" less drop at 400 yds is some huge advantage??"...yeah right!!

Nobody is right, they are just defending what they own and shoot. What you believe and choose to spend your money on is up to you, it all works.

JimF

my experience with ai cartridges is and has been quite satisfactory.i have found them to be vey accurate, faster,brass life is extended quite a bit[less stretch due to the shoulder angle],fireform loads can be quite accurate aand have noticed less wear on the actions that these chamberings were shot out of,because of less bolt thrust due to the sharp shoulder.the debate here seems to fall on the cartridges being overbore to begin with.many cartridges are very well suited to the ai configuration and in the same breath many are not. it really comes down to the cartridge itself example-the 260 rem is not a good canidate for the ai considering u really dont gain that much more velocity.in this case it comes down to the fact that u can use 6.5x284 which still fits into a short action has far better velocity potential and is still not overbore.on the other side of the coin there is the 7-08 which is great for the ackley configuration as well the mentioned 7x57,u can squeeze more velocity out these cartridgesand have the above mentioned benefits[although the new 7wsm has made this a moot point],but before the wsm line u simply could not get the performance out of any other short action cartridge that u could get withe 7-08ai or the 7x57ai,while still having cartridges that were not over bore.in regards to pressures of course u are running at higher pressures-ackleys are a no mans land proposition[there is no standard 4 pressure except ones better judgement ].i personally am a huge fan of the 7-08ai and will always be.i can push 140g bullets at over 3050 and depending on the bullet the and the bc of that of that bullet i have great downrange potential as has been proved by my 7-08ai and many others.the 7-08ai gives a slight edge over the 280rem. and 270 win and is easier on barrels.what i am trying to point out is that in some cases the ai is an excellent choice in some bore sizes where more performance could not be attained w/o going to a long action or a belted cartridge ,or going to overbore cartridge.the only real downside to the ai setup is feeding from a mag[which isnt so good]and fireforming but like i said accuracy frome most ff loads can be quite good.i dont see 25-06 as being a good choice 4 the ai configuration as it is already over bore[although if thats what one wants so be it.]the 257ai is one the finest there is performance is right there with there with the 25-06 with less powder and recoil.if one wants more performance the 25-06 in a .25 bore then there is the 257weatherby which has its merits but is way overbore.enough of my rambling and i hope u understand what i am getting at-my2-dave

One of the reasons why there is such a remarkable "improvement" in the .257 Roberts AI and the 7X57mm AI versus the standard round is that these rounds are significantly underloaded in the U.S. There's not as much difference between the "standard" and the AI rounds when the standard case is loaded to up to its full potential by a handloader!! If you don't believe this, just look at how the regular old 7X57mm and 8X57JS rounds are loaded in Europe!

Ive noticed that most rounds that seem to benefit the most from being improved, with the exception of the 223, have more taper too them which when improved also adds to powder capacity. Thats why rounds like the 257, 7x57 and 375H&H benefit more than the ones with less taper like the 06 class or a .308.

KLN,

The quotes you gave need a bit of a disclaimer. First off the statement of: "Since the original .270 is over bore capacity, little improvement can be expected...." and "...due to its relative inefficiency, it is not recommended...." is a quite outdated.

Over-bore capacity is a term used in reference to the canister grade powder(s) available which can provide a charge that fills the case without raising pressures above the safe recommended levels (ie 65,000 PSI). With the available powders of today, the 270 can be: at, under and over-bore capacity. For example, if you were to use Alliant Unique in the 270, you would have a situation where the case is dangerously over-bore capacity for the powder. If you select powders like IMR-4831 or R-19, the 270 case falls into the �at� bore capacity. At the same time, if you choose a powder like 50 BMG, you would be at the extreme opposite end of the spectrum, with a case that is Under bore capacity. Offhand, I can�t think of any cartridges today that are �over-bore� capacity for any of the powders available on the market.

��and hard on barrels..."This is something that has many people heavily criticizing magnum cartridges. It�s a misunderstanding that has more to do with the pressures the cartridges are running at, rather than the small 5% increase in powder. This is particularly evident in the reasoning behind the Howell line of cartridges. If you take a small case and constantly run it to critical pressures � a point where the pressures raise to a peak level that liquefies a thin layer of steel � at every shot, the barrel will wear out quickly. This can happen to virtually any case (22 short as an exception??) This was more assuredly the case with many of the Ackley cases. It would almost have to be in order to reach the claims of approx. 150 fps increase in velocity. On the other hand, if you are to take a large case, and load it to the same velocities of the smaller case, but with much lower pressures, your barrel life will be drastically increased.

I myself use a 338-06AI and have no problems with feeding out of my stock 700 BDL action. The cartridge capacity is still the same in the magazine, and because you have to fireform the cases for ALL cartridges in order to obtain optimum accuracy regardless of the design, this step doesn�t bother me.

The dies are more expensive (I think I paid 150ish CAN from RCBS), but they were made for my rifle. I�m simply not physically able to over size my cases, even if I wanted to. The die is just set up that way. As was already stated, the velocity increase isn�t all that it is cracked up to be. Although, if you just want the rifle for the novelty, or the fun of having it, go for it. If you don�t like it, you can always have it rebarreled or rechambered to something else.

Turok

Interesting thread. I'm going to agree with some of what's been said and disagree a little, as well.

I built a 7-08AI a few years ago. I already had a 7-08 in a Mountain Rifle. I liked it so well I decided to build a custom rifle, but built it in the AI version. It didn't cost any more to have the new Shilen chambered in the improved configuration. I bought the new 7-08AI Redding dies at a gun show for $39.00. So far, no big deal.

No, I didn't expect to gain magnum velocities with the AI. I was originally interested in attaining standard 7mm-08 24" barrel velocities from a 22" barrel with the AI. I built this rifle for carrying around in the field. Even with a 22" barrel I don't have any problems reaching 3000fps with 140gr bullets, and it shoots itty bitty groups.

One year I drove all the way up to the farm for deer season and forgot my ammo. I stopped at Wal-Mart on the way up and picked up some standard 7-08 ammo. It headspaces on the same datum line. It worked just fine, although I did have to fire a couple of shots when I got there to change the elevation setting on my scope. Although I gave up a little velocity with factory ammo in the AI chamber, the deer didn't notice the difference.

Brass life is greatly extended, since there is less case stretching, and there is significantly less wear and tear on the bolt lugs and lug recesses with the straighter sidewalls. Extraction is also easier. And since the AI chamber is cut by a gunsmith working on one rifle at a time, the chamber probably has far less slop or wobble, and is better aligned with the axis of the bore for enhanced accuracy. The result? A fireformed case with better concentricity. As far as AI cartridges burning throats? How? Don't buy that one.

I still don't understand the comment about headspacing and case head separation. I've seen case head separation plenty on belted magnums. The usual cause? Inexperienced reloader headspacing on the belt rather than the datum line of the shoulder. Even once fired factory brass can stretch beyond the point of no return with the generous headspacing and sloppy chambers of factory chambered magnums. Never have seen that happen on an AI chambered rifle. The handloader would really have to be an idiot (Idiot: doesn't know what he's doing and doesn't ask for help from a knowledgeable person). It's not difficult to set up a sizing die so as not to set back the shoulder. With the sharper Ackley shoulder, there is definitely more positive headspacing.

Brass preparation is no different for an AI cartridge than any other cartridge. Yes, the brass needs to be fireformed in the Ackley chamber, but that doesn't mean that you are wasting bullets, powder, and time. I've developed some very accurate fireforming loads that don't need to be shot at the range.

And to top it all off, it's a very SEXY looking number!

Back to the 25-06AI. If you don't have a 26" barrel that can utilize the slow burning powders available today, you could call it overbore. As long as it shoots straight and does what you want it to do, SO WHAT! Go for it! Especially if you can pick up this rifle for only $400.00. I'll spend that much buying a rifle just to get a decent action. Sell the barrel and stock at a gun show and put a McMillan stock and a Shilen barrel on it, and presto! Another semi-custom toy! When you burn up the barrel, just put another one on it. No big deal!

[ 02-07-2003, 10:06: Message edited by: SST ]

"If you don't have a 26" barrel that can utilize the slow burning powders available today, you could call it overbore."

You wont burn anymore powder in a 26" tube than you will in a 24", or even a 22" bbl for that matter. This has everything to do with 'all-burnt', where there is only a certain portion of powder that will be 'all-burnt' regardless of how much you have in a case or length of the bbl. And it certainly has nothing to do with being 'over-bore'. I will agree that you will get more fps with a longer bbl., but not with the idea that it is 'over-bore'.

Turok

True,
Overbore is overbore. Longer barrels do, however, reduce the amount of ejecta, and utilize the benefits of slower powders more efficiently.

I know of two (there may be more), really "improved" Ackley Improved cases; the 250 Savage AI and the 7X57mm AI. Some would also put the .257 Roberts AI in this group. Ackley himself considered the .250 Savage AI the best of all .25 caliber rounds, and it just might be....

My 25-06AI is in a 24" tube,it thrives on the 100gr XLC with Re-22,right at 3600fps.

No it's not as fast as my 257Wby's,because it isn't of enough capacity. But it still makes very nice speeds from readily available brass and will house another round in the magazine,all while happily digesting off the shelf 25-06 ammo should one be so inclined(I'm not,as my preference is to load). All of those are positive attributes,in my opinion.

I'm an Improved cartridge fan and think especially highly of the 25-06AI............

I have a 25-06 AI and love it. It shoots damn good and has been easy to work up loads that shoot well. My only gripe about anything in "improved" is the time spent creating your AI brass. Lot's of fireforming, cheap bullets, IMR4895 and stuff like that. I will say this, it is fun and the rounds are good.
Shot a great big buck with it this past fall at 250 yards and the Nosler BT did its job. That deer is gonna look good on my wall.
I would say that if you want something different and don't mind the extra work creating your AI brass then go for it. I do not know the velocties because I do not own a chrony but at 400 yards I get to save 3 inches or so of drop now. I like mine. Cheers, Jason

SST

You are still using the term overbore incorrectly. As was already stated, overbore has everything to do with a powders ability to fill a case full, while producing safe levels of pressures. If you stoke the 25-06AI full of 50BMG, it would be way underbore. That is, you couldn't hit excessive pressures before you ran out of room.

All-bunrt is a very real thing, and it is a process that takes place within the first few inches of the barrel so adding 2 to 4 inches at the END of a barrel essentually has no effect on the actual capacity of the case. Once this point is reached, no more powder will be bunrt.

I think you are referring more to the overall efficiency of the case where adding X amount of additional powder will only give you a smaller Y amount of increase. Adding a longer barrel in this case will improve the appearance of the case's efficiency, i.e. more fps, but it wont improve on all burnt. And it wont make an 'over-bore' case 'at' or 'under-bore'. That is not what the term means.

Turok

I form with bulk R/P 100gr Core-Lokts and shoot them molied in front of Re-22.

It makes for excellent practice rounds,that give up little to typical 25-06 velocities,while maintaining excellent accuracy. I formed 300pcs of brass in short order,playing with long range steel targets,via a target turret and a laser. I regret none of it.

She's often discounted,but always by guys who never had one. I see a familiar trend,in that regard................

I like to form cases for my 257AI with cheapy bulk 100 R-P Core-Lokts and a mid-range load of I4895, with bullets seated to hit the lands. Shot some sub 1/2" groups with it while doing so, without taking any special "benchrest" precautions, so, I have to take exception to the "won't be as accurate while fireforming" contentions. Why would it be any less accurate?

R-WEST

Turok,
Please disregard my comment about "overbore". We're on the same page. In reality, "overbore" almost always refers to somebody else's rifle, irrespective of the cartridge.

It would helpful if you were better able to know what I was really thinking rather than paying close attention to what I was actually typing.

[ 02-08-2003, 03:23: Message edited by: SST ]