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Discussion in 'Reloading' started by Greg Duerr, Mar 12, 2013.
Does anyone have any experiance with this Cartridge? The performance over the standard case?
I thought Ackley did this case, but it appears that he didn't. The 6.5x55Arch is what he published in his book, and it looks similar to an Ackley design. There's also the 6.5 Vias, and the 6.5x57 (several). These are nothing more than an improved .257 Roberts necked upto 6.5mm. There seems to be some interest in this round with 1000 yard shooters these days. Plus Kiff has several different reamer prints.
Below is an old post that I saved from years ago on another forum that has some good info in it regarding Ackely. I bolded the part specific to the 6.5x55.
It is important to note that the author was loading to the standard low pressure requirements of older 6.5x55 rifles. If loading to what a modern action can withstand both the standard Swede and the improved will see velocity gains. It is still good info though, to see what kind of improvement can be had by going to the improved version.
[FONT="]Good to hear from you and especially about those fine old-time Ackley Improved cartridges. As you know, Ackley was far ahead of his time…and far ahead of all the commercial cartridge companies in improved design. He was our last great cartridge experimenter who could and did write about his work. Today we seem to have arrived at a point where we have experimenters and we have writers, but the two almost never meet! The great Ackley handbooks, Volume I & II, Handbook For Shooters & Reloaders, is in need of updating, but it would be a major undertaking and would require the input of some top experimenter and/or writer. If you inspect the loading data in those two books you will immediately notice the outdated, discontinued powders and the fact that he almost never gave barrel lengths along with velocities. Also, a number of the cartridges in Ackley’s books listed data from other sources such as directly from the designer who estimated most velocities, optimistically. But in spite of these minor disparages, Ackley’s books are still the experimenters bible, just loaded with technical information not found elsewhere.
Before getting into your questions concerning the Ackley cartridges with the best percentage improvement, smallest improvement and the ones left in the middle, perhaps you would have an interest in Ackley’s background…just to pass on to your friends in the hot stove league involved in the Ackley arguments during cold winter days. Parker O. Ackley was born in Granville, New York, graduated from Syracuse University in 1927 and nine years later started his first gunsmithing business in Roseburg, Oregon, 1936. He was with the Ordnance Department during World War II and then moved on to Trinidad, Colorado to open what was to become one of the largest custom gun shops in the country. He also taught at Trinidad State Junior College where his gunsmithing school became world famous. He moved on to the Salt Lake City, Utah area where he continued his shop and did a great deal of experimental gun work. Along the way he became widely known as a gun writer where he passed on his knowledge of the trade. He left us all in 1989 at the ripe old age of 86.
The first cartridges designed by Ackley in the so-called Improved shape simply straightened out the tapered case body, giving the original factory designs a more straight walled dimension and leaving the shoulder angle the same. While this proved to reduce back thrust on the bolt, it still showed some case stretching in the neck and shoulder area that resulted in continued case trimming. When he changed the shoulder to something like 30 degrees the case lengthening slowed and by the time his designs reached 40 degree shoulders, all case lengthening stopped, within reason. It became common to reload those cases 15 – 20 times without having to trim them. Thus, the benefits of the famous Ackley Improved cases became reduced back thrust and elimination of case trimming. Case extraction became easier and more positive and loading pressures could be increased safely, resulting in higher velocities. Another interesting feature of these Improved chambers is the fact that standard factory cartridges can still safely be fired in the rifle. There are some die makers that still offer Ackley dies with the milder shoulders, so when ordering loading dies it is prudent to specifically request the 40 degree shoulder model.
Now to get on with your questions. There are more than 20 Ackley Improved cartridges, plus dozens of Ackley Wildcats, but some have about gone into obsolescence because the parent cartridge is no longer being loaded by the factories. Thus, brass is difficult to find. Of those that are alive and well today, the percentage of velocity gain over factory loadings ranges from about 3% up to 17%. A couple of others exceed this gain, but the parent cartridges are no longer being chambered for by the rifle companies. When we compare the Ackley Improved cartridges to handloaded standard factory rounds, the velocity gain ranges from zero up to a little over 12%. From this you can see there are a few Ackley Improved cartridges that may not be worth the trouble and expense to chamber for. But on the other hand, there are several that will simply blow you away with their new velocities, especially when compared to some of the much larger factory belted magnums, the big boomers.
There are many sources of cartridge velocities available today. These include factory listings as well as the dozen or so reloading manuals. This means there are many different barrels being used to arrive at those velocities. And that is why we, as handloaders and experimenters, must utilize several loading manuals in order to arrive at some norm that can be our starting point. When searching for the proper velocities to pass on to you to answer your questions, I first took the factory listed data from several cartridge companies and used their best figures. Then I utilized Ackley’s book figures, plus data from various other sources where barrel length and chronographed velocities were shown. This meant that some information differs from that found in Ackley’s books due to using new powders, stating the barrel lengths and chronographing over electric chronographs instead of the old pendulum style used so often by Ackley. In all cases pressures could only be observed by common shooter’s methods, that is, by checking primers, primer pockets, case heads, extraction, case life, etc. Generally, pressure guns using the crusher-gage method and resulting in copper units of pressure (c.u.p.) are not available outside the ballistics labs. This is also basically true of the more modern electronic-transducer gages that record in pounds per square inch (p.s.i.). These methods of discovering chamber pressures result in disabling the rifle by drilling into the chamber or at least attaching wires to it. It should be remembered that pressures given in c.u.p. are somewhere around 15% lower than those found in p.s.i. recordings, and when using various books giving pressures be sure to notice when two different methods are being used.
The best velocity gain of all the Ackley cartridges compared to the standard factory cartridge comes with the .25-35 WCF with a 117 gr. bullet and a gain of about 25.6%. The second best is the .30-40 Krag and the 180 gr. bullet showing a velocity gain of 19.3%. Both are rimmed cases and neither one is being chambered for today. Therefore, we will start with the third best velocity gain of 17% as found with the little .250 Savage when converted to the Ackley configuration and loaded with the 100 gr. bullet. Our rifle companies have chambered for the .250 Savage from time to time, but it is rapidly becoming obsolete in spite of the many knowledgeable shooters who use it regularly. The factory .250 Savage load is 2820 fps, while the .250 Ackley attains close to 3300 fps. This little speedster can equal or exceed the factory velocity of the much larger .25-06, listed at 3220 fps. And it is being done with 15 – 20 grs. less powder which means a great deal less recoil for the same velocity and trajectory. This is downright amazing…. And all this is being done in a short action. This .250 Ackley cartridge is not shown in any modern reloading book that I know of. Some books do show another .25 caliber, the .257 Ackley, that lands farther down the line in eighth place for best Ackley percentage gainers. I have used the .250 Ackley for both varminting and big game hunting with outstanding results. [/FONT]
[FONT="]For the next best gain, number four in the chart provided, I am taking my writer’s prerogative to show a standard cartridge that Ackley did not work on, but is now known as the 6.5x55 BJ Ackley Improved, the initials being my own. In the early 1990s I thought the standard 6.5x55 Swedish cartridge would show nice gains if it were improved as an Ackley. Little did I know that Ackley never did it. But to make a long story short, I got busy and copied the Ackley design into the 6.5x55, with a great deal of input from Dave Manson of Manson Reamers. With the 140 gr. bullet the velocity gain is 13.7%. Standard factory velocity is 2550 fps, while the 6.5x55 BJ Ackley gets 2900 fps. This is another Ackley cartridge that I have used extensively for hunting, and I have heard from several readers who use it in long range competitive shooting.
Fifth in the chart is a surprise – the .30-30 Ackley. It shows a gain of 12.9% over the factory load with the 150 gr. bullet. The factory shows a velocity of 2390 fps, and the Ackley can skip along at 2700, even from common lever action rifles according to Mr. Ackley. That just happens to be faster than the factory .300 Savage, and yet it is the good old fashioned, century-old cartridge, improved.
Sixth best gain belongs to the 7x57mm Ackley. Since we have properly verified loading information in the Speer #2 Manual, those are the figures we used and thus the Ackley beats the factory 7x57mm Mauser by 12.8%. The 7x57mm Ackley equals the factory .270 Winchester and does so with 10 grs. less powder and less recoil. Ackley said this cartridge has the ideal capacity for a 7mm, and is powerful enough for all North American big game hunting. I have friends who use this one, and it is outstanding.
The seventh place round is another surprise to most shooters. It is the .300 H&H Ackley Improved, with an increase over the standard factory round of 11.1%. The factory loads the .300 H&H with the 180 gr. bullet to 2880 fps, while the Ackley gives 3200. There have been a number of improved .300 H&H cases, including the .300 Weatherby. They all headspace on the [/FONT][FONT="]case belt[/FONT][FONT="], so the case body can be blown out to most any shape. Loads for the Ackley and the Weatherby are the same. Ackley always stated that these blown-out belted magnums are all badly over bore capacity and greatly inefficient compared to the standard H&H. Barrel life is short and faults far outweigh all good points, which seem to be limited to perhaps better case life when headspaced on the shoulder instead of the belt.
And now we arrive at number eight, the .257 Ackley with a gain of 9.4% over the standard .257 Roberts load of 2650 fps with the 117 gr. bullet. The Ackley gets 2900 fps with the same bullet. If we use the Winchester +P load of 2780 fps for the Roberts, the Ackley gain drops to 4.3% and the cartridge is not worth chambering for. This shows very plainly how poorly the factories have historically loaded the fine .257 Roberts.
This takes care of the best eight Ackleys, in order, compared only to standard factory loads and not with all bullet weights available. And we must remember that every barrel gives different velocities, so those listed here may vary from what other experimenters might achieve.
Now we will go to the other extreme, the poorest of the Ackleys. Ackley tested many cartridges that he knew before he started would show poor results. But with so many shooters asking about them, he felt obligated to prove just how inefficient they might be. And in some situations the Improved case actually showed zero gain! A good rule of thumb concerning Improved cartridges is that unless the gain reaches a minimum of 6% the project is not worth doing. Loading books often show peculiar numbers, some even appear to be incorrect. An example would be when a book shows a top load for a heavy bullet and then reduces the same powder when loading a lightweight bullet. Since a lighter bullet can always utilize more powder, that book value simply cannot be true. That is why experimenters with chronographs find such interesting things…. Of course, there could be extenuating circumstances that the book did not mention, but should have.
The worst of the Ackley Improved cartridges has captured last place in the chart, number 25, and is the 6mm Remington Ackley Improved with the 100 gr. bullet. The factory lists 3100 fps, and the top load found for the Ackley is only 3200 fps. This is a gain of just 3.2%, and is surely not worth going after. Even the 75 gr. load shows a marginal gain, as we shall see.
From the bottom of the chart, holding down number 24 of the 25 listed loads, is the .257 Ackley Improved when compared to the.257 Roberts factory +P load of a 117 gr. bullet at 2780 fps. The Ackley only gains 4.3%, or up to 2900 fps. This is another Ackley round not worth chambering for. Some books require close reading because they list the standard .257 Roberts with a 22” barrel, while showing the .257 Ackley with a 26” barrel. Assume 25 fps per inch of barrel and you have to remember to either add 100 fps to the standard velocities, or subtract 100 fps from the Ackley readings in order to make a proper comparison.
Tied with the .257 Ackley with +P loadings in 24th place is the .260 Remington with a 140 gr. bullet factory listed at 2760 fps. The .260 Remington Ackley Improved sends the same bullet off at only 2880 fps, or just 4.3% gain. This is well below the rule of thumb of a 6% minimum gain before making a change to any particular Ackley. It also is one that Ackley did not design as such, but did work with as a wildcat cartridge back in his day, the 6.5mm-08.
The fourth worst is the .22-250 Ackley with a 55 gr. bullet at 3850 fps. The factory .22-250 gets 3680 fps, which means the Ackley only gains 4.6% over the factory round. Here again, if we abide by our rule of thumb when chambering for any Improved cartridge, we would have to pass on this one.
Next on our list is one not too many shooters have interest in, the .375 H&H Ackley loaded with the 270 gr. bullet. The factory .375 H&H sends that bullet off at 2690 fps, while the Ackley gets 2830 fps, a gain of 5.2%.
The sixth cartridge of the less than desirable Ackleys is one from a logjam of three, the 6mm Remington Ackley with the 75 gr. bullet, as mentioned above. Here we find the standard factory 6mm Remington sends off the 75 gr. bullet at 3400 fps, and the Ackley only gets 3600, for a gain of 5.9%. This is close to the 6% required by our rule, so some shooters might decide to chamber for this one. And this particular cartridge shows that some cartridges are better with one weight of bullet than with another. The 100 gr. in the Ackley is not good, but this 75 gr. is perhaps acceptable.
Second out of the three-way logjam is the .220 Swift Ackley with a 50 gr. bullet at 4100 fps. This is a 5.9% gain over the factory load of 3870 fps, and again, some shooters might go for it. But there are other Ackleys that are better, or at least more efficient. Historically, none of the Improved Swifts have done very well, including the .220 Weatherby Rocket of days gone by.
Third of the three-way tie is the 7mm-08 Remington Ackley with a 140 gr. bullet at 3030 fps. The factory 7mm-08 gets 2860 from that bullet and the Ackley gain is again 5.9%. It is noteworthy that this Ackley load outperforms the factory .270 Winchester with the same bullet weight, and does so in a short action.
Right on the borderline of our rule of thumb for getting involved in is the old-time .219 Zipper, no longer being chambered for. The factory load with a 55 gr. bullet is 3300 fps, and the Ackley can achieve a velocity of 3500 fps, a gain of 6.0%. This is a rimmed cartridge and just about obsolete, with very little demand.
This now leaves us with the so-called middle ground calibers. They are all in the acceptable or better range of Ackleys, but of course some may be a bit more desirable than others for various reasons. Some only make the list with one particular bullet weight, or they make the list twice in different positions due to bullet performance resulting in different percentages of gain. Not all bullet weights are considered. The chart will show details of this, so here we will only list the cartridge and the gain, from best middle ground to worst. In gain order, the .270 Winchester Ackley, 8.8%; .25-06 Remington Ackley, 8.4%; .375 H&H Ackley, 8.3%; .243 Winchester Ackley, 8.1%; .270 Winchester Ackley, 7.8%; .280 Remington Ackley, 7.7%; .30-06 Springfield Ackley, 7.4%; .30-06 Springfield Ackley, 6.5%.
As you can see, each of the Ackley cartridges has its own story. It would fill a fat book to even begin passing on all the stories, but maybe this information will be a start for you. The chart with this will show all these Ackleys and their gains in velocity. It should give your hot stove league plenty of grist for another long winter.
Keep shooting, and hopefully with one of those Ackley Improved cartridges.
PS & TAR Staff[/FONT]
got to do some arguing with Bob on his data.
1. I've never seen any factory load in a 22-250 do almost 3700 fps! As in zero! Maybe 3550 fps max out of a 26" barrel. Hand loads are good for about 3650 fps max (I have never been able to get there). What guys are showing out of a 22-250AI I can't say as i only know a couple that shoot it. But he has stated more than once that the main reason he did it was to contain brass flow.
2. The 30-06 family would also apply to case life issues and brass flow
3. I shot the 6mm Remington for years and he must know a source for 70K psi loads! The hottest loads I saw were with necked down .257 Roberts brass (very old stuff with thinner case walls) were in the 3400fps range and an 80 grain Blitz. The loads were very hot! Factory ammo was down a hundred fps or more. The 6mmAI was good for about 175fps more velocity, but the cases held up better
4. the .257 Roberts (I've only seen factory +P ammo twice in my life) with a 117 grain bullet is good for the 2700fps on a good day. Hand loads are good for about 2750fps, but think 2800fps is doable. The only load data I have for +P ammo is from AA, and thier 117 grain data is about 2740 fps (seems light). Their Ackley data on the otherhand shows the same bullet at 3099fps. Also seems light.
Being as the Roberts case and the 6mm thru 7mmAI share the same basic case, one would think what's good for one is also going to be good for the other. Yes and no is the answer. The velocity gains in the 6mm will be less as the standard case is about it for the 6mm bore. But there is a substantial velocity increase anyway. Ackley said more than once that his best cartridge design was the 7x57AI (same case). Yet the velocity gains were not as much as most think if 300 fps dosn't mean a lot with a 140 grain bullet. Hogdon shows 2800fps max in their manual, while Ackley shows a tad more than 3100 fps. Bob spoke of the 75 grain bullet in a 6mm Remington. Ackley gave loads for about 3500fps using H380 powder. Yet he shows 3700fps with the same bullet out of the improved case. Hogdon's manual is a little slower at around 3400fps. AA data seems much hotter, but they also don't do a 75 grain bullet (they did get 3600fps with a 70 grain bullet which seems very hot to me). Ackley shows a little over 300fps gain with the 250 Savage case and a 100 grain bullet
Bob seems to have based everything off of velocity gains, but not every case was done for that issue alone. Many were done to decrease the flow of brass (Swift comes to light as well as the 30-06 cases family). Still a 225 grain bullet in a .338-06AI is good for about 2850fps. But at 500 yards the difference is about 300ft. lb. of energy. That's a nice gain in knock down power. (about 10%).
Some of what you stated was discussed in other posts on the thread. You are correct, the point of the thread was velocity advantage for Ackley's, even though we all know there were other reasons just as valid like brass life, etc. I wish I could remember all of the details but I think he had specific pressure thresholds for each caliber in an attempt to try and keep an apples to apples comparison. I do remember not understanding why some were chosen. You listed some you thought were high, IME some of them are low as well but the reason I posted the info is because it does show how well some do with velocity increases vs their sammi counterpart. And the Swede does show big increases in that regard, although like I said the velocity numbers are scewed vs what I can get out of a modern action.
I just didn't agree with Bob's notes. Some by experience, and others by simply looking at the loading data. The one that really surprised me was his 6mm data, and yet it had points that a lot folks won't pick up. Most load data in the manuals at max is not max in any way. The 6mm Remington is a 65K psi round, yet most loads you see are well under 57K psi, so that maybe where Bob was comming from. I have shot both the standard 6mm and the 6mmAI in the past, and I've found that the most you get with the Ackley is about 175fps, with one exception and that was maybe 215fps. The standard 6mm case is about it for the 24 cailber bore without going into overbore. The Ackley case takes it beyond that condition and into overbore unless you are talking about 100 grain and heavier bullets. Then there's a difference. Personally I've long felt that the ideal case for the 6mm would be the 6.5x55 necked down to 6mm, and blown out in the ackley configuration. But with a 1.65" shoulder length and a .33" neck length (or .35"). This round will sorta bridge the gap between the .243 and the 6mm; yet be like the 6/250AI on steroids. Better neck length is gonna help guide those 107 grain bullets, and I honestly think it's gonna produce close to 3200fps with the 107 grain Sierra bullet. A fireformed case ought to drop right in with a .330" neck length after shrinkage.
I did find out that I had some other .257 RBT's +P data in a Speer manual, but it's almost identical to what AA published. But Bob is right in that the Ackley 257 is good for maybe another 200fps on a good day although AA claims about 300fps difference with a 117 grain bullet
To further touch base on the improved 250 Savage case design. I shoot that case necked down to 6mm, and it is one efficient little case! It will push a 105 grain Amax to 3000fps without excessive pressures (still pretty hot). Needs a longer neck for the longer bullets. I don't use 250 Savage cases, but use generic .243 cases. I tried necking up 22-250 brass, and fireforming it, but case shrinkage was excessive! Looking at a reloading manual oneday I noticed the shoulder deninsions and angles of the .243 case verses the
22-250 case.Using the .243 case instead of the 22-250 displaced a lot less brass. Thus far less shrinkage (about 40% less). I shoot the standard 22-250 a lot. I've long felt that the case was getting very close to overbore, but still acceptable. Looks to me like the gains made with the 22-250 AI are minimal unless you are lucky enough to have a 1:9 twist Savage barrel. Then you could make use of the extra powder capacity. By the way that 250 improved case has gone from 20 caliber to at least 30 caliber over the years. I'd like to think that a .300 Savage case necked down to .257, and run thru a .250 Savage die might be a better combo. Cut the necks back to about .33" after fireforming.
It has been some time since i have had an opportunity to get the old 6.5X55AIX40 degree as marked on the dies that came with the rifle. Looking at case capacity very similar to 6.5 X 284 still nervous about loading without proven loads. any help would be greatly appreciated. Fred gun)
Here's a great thread with lots of info. Be careful though. There is a mix of standard 6.5x55 and AI recipes but all are at traditional pressures.
Sniper's Hide - Long Range Shooting, Precision Marksmanship, Gear Testing & Reviews - Scout Front Page
Thanks for the reply I found enough to get me started I'm an old wildcatter. I going to start with H 1000 and possibly try RE-22. I happen to have a large amount of WC-872 Military pull down powder on hand from the 90's I am itching try. I use it for heavy bullets in my 30X375MR 7MM Rem Mag and 25 Gibbs WC 872 I was told used for 20 MM cannon rounds. From my experience the bullet weight needs to at least twice the powder weight and compressed. I believe the 6.5X55 AI is a good platform to try it. Again thank you fro the lead. Fred