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#2917427 - 03/28/09 270 AI?
2Seventy Offline
Campfire Regular

Registered: 03/27/05
Posts: 575
Loc: Idaho
I hear quite a lot about the 280, why not the 270 AI? What are the pluses and minuses of this caliber?


270

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#2917509 - 03/28/09 Re: 270 AI? [Re: 2Seventy]
Mark R Dobrenski Offline
Campfire Oracle

Registered: 04/19/01
Posts: 28277
Loc: Bozeman, Montana
One plus is it fits in a short action, thinking it's called a 27 WSM...grin

Dober
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#2917653 - 03/28/09 Re: 270 AI? [Re: Mark R Dobrenski]
BobinNH Offline
Campfire Oracle

Registered: 01/28/07
Posts: 30701
One minus is it's no longer a 270 Winchester
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#2917868 - 03/28/09 Re: 270 AI? [Re: BobinNH]
ingwe Offline
Campfire Oracle

Registered: 12/20/08
Posts: 57827
Loc: Southwestern Montucky
OK you guys... somebody just had a thread about a7mm cult, and you, plus a buttload of others I know worship at the altar of the .277 calibre boolit.
I have never given into the demon .277 diameter, but stick steadfastly with the consummate,ultimate boolit- the .284 diameter....what have I been missing all these years??? \:\(
Seriously, help me out... bring me in to the light....
Ingwe
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#2917910 - 03/28/09 Re: 270 AI? [Re: ingwe]
cumminscowboy Online   content
Campfire Guide

Registered: 11/11/04
Posts: 3364
I have no idea why so many guys do a 280 AI some are the same guys who say a 270 AI is not worth it, maybe the 280 AI deal is fashionable, look at the AR 15 tactical crowd, its monkey see monkey do with them, this may be the same way

if you really wanna go faster on a 270 win case, do up a 270 gibbs
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#2917920 - 03/28/09 Re: 270 AI? [Re: ingwe]
Mark R Dobrenski Offline
Campfire Oracle

Registered: 04/19/01
Posts: 28277
Loc: Bozeman, Montana
Ingwe-once you get your pawz on what Arnold is settin up 4 me then you'll see the light...grin (well maybe, it'll still not have the sizzle that your 275 Rigby does)

Dober
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#2917980 - 03/28/09 Re: 270 AI? [Re: cumminscowboy]
kenaiking Offline
Campfire Guide

Registered: 11/08/04
Posts: 3937
Loc: MONTANA
 Originally Posted By: cumminscowboy
I have no idea why so many guys do a 280 AI some are the same guys who say a 270 AI is not worth it, maybe the 280 AI deal is fashionable, look at the AR 15 tactical crowd, its monkey see monkey do with them, this may be the same way

if you really wanna go faster on a 270 win case, do up a 270 gibbs


I think it has a lot to do with availability of components (dies and reamers mostly) and smiths who have them.

Its pretty darn hard to find .270AI gear plus a smith who has a reamer in the drawer. 280AI easy as pie.

If you really wanted to get into it the .280 has the slightest advantage. About 2 grains more powder, higher BC's , higher SD's and more bullet choices. That said its not enough to matter in a hunting situation but it is stuff that keeps you up at night. Or starts 50 page discussions in a campfire forum
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#2918117 - 03/28/09 Re: 270 AI? [Re: ingwe]
BobinNH Offline
Campfire Oracle

Registered: 01/28/07
Posts: 30701
INGWE: To answer your question it goes like this,and is just my opinion,but if we look back,we see some things are perceived as needing "improving", so they get improved......and some are not.....so they don't.

For some reason, the 7mm's have been played with every which way,and the 270 Win,while remaining enormously popular,has been given scant attention when it comes to improvements.The only exceptions being the 270 Weatherby,and the 270 WSM,both of which make their presence known in the markets,but have only a fraction of the popularity of the 270 Win......so,

I can only conclude from this, that the 270 Win has done just fine all these years,has needed no embellishment,improving, etc,and I think Winchester got it "right" the first time.Just not much to improve upon
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#2918241 - 03/28/09 Re: 270 AI? [Re: BobinNH]
ingwe Offline
Campfire Oracle

Registered: 12/20/08
Posts: 57827
Loc: Southwestern Montucky
 Originally Posted By: BobinNH
INGWE: To answer your question

I can only conclude from this, that the 270 Win has done just fine all these years,has needed no embellishment,improving, etc,and I think Winchester got it "right" the first time.Just not much to improve upon


From what Ive seen in the field and in the gun Biz ( yeah Ive sold a couple firearms...dont tell the administration!)I'd say you hit the nail on the head..The .270 Win. works well IMO with boring regularity....Ive only seen the .270 WSM put to use once, but it was "flat" impressive.And yeah the 7mm has been messed with in every concievable way,since the 7x57 was introduced as the first smokeless cartridge...only makes sense.By the time JOC and the .270 came along, they already knew how to build a really good cartridge. Bit of trivia, the Germans even had their V1 and V2 ( I think) Rockets built around the enlarged dimensions of a 7mm bullet,because of its perceived ballistic efficiency,IIRC.
Anyway, I'm gonna sneak around to the gun shop and fondle that .270 thingy Dober was talking about! \:D
Ingwe
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#2918260 - 03/28/09 Re: 270 AI? [Re: ingwe]
BobinNH Offline
Campfire Oracle

Registered: 01/28/07
Posts: 30701
Ingwe,don't get me wrong because I'm a 7mm maven myself.Provided case capacity and bullets are roughly similar, I see the two calibers as being twins and what one will do the other will do as well.Both are good,both do the same work,and I am finding myself coming down with a hankering lately for a 7x57 \:o

And I can't listen to logical arguments about the 308 and 7/08 being as good as the 7x57,which may be true,but I really don't care...they are not the 7x57 ;\)


Edited by BobinNH (03/28/09)
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#2918307 - 03/28/09 Re: 270 AI? [Re: BobinNH]
Azshooter Offline
Campfire Guide

Registered: 01/17/02
Posts: 3017
Loc: Tucson, Az.
I just did a search for the 270 AI and found this fascinating article from Precision Shooting. It is long but the percentage gains of various AIs are mentioned including the 270 AI. The 270 AI is mentioned near the end of the article. Thanks to Bob Jourdan PS & TAR Staff:

Article posted on Precision Shooting Website about Ackley Improved cartridges

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.

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 (PS advertiser). 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 case belt, 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.


Bob Jourdan
PS & TAR Staff

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#2918514 - 03/28/09 Re: 270 AI? [Re: BobinNH]
ingwe Offline
Campfire Oracle

Registered: 12/20/08
Posts: 57827
Loc: Southwestern Montucky
 Originally Posted By: BobinNH
I am finding myself coming down with a hankering lately for a 7x57 \:o

And I can't listen to logical arguments about the 308 and 7/08 being as good as the 7x57,which may be true,but I really don't care...they are not the 7x57 ;\)


Bob;there is no room for logic in these discussions...if there were, we'd all be shooting the same caliber ( almost any one of them, take your pick, they all work well...) and just maybe I wouldn't be shooting the oldest- and one of the slowest- and just maybe you wouldnt have a hankering for same... ;\)

Ingwe
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#2918521 - 03/28/09 Re: 270 AI? [Re: ingwe]
VAnimrod Offline
Campfire Oracle

Registered: 04/21/04
Posts: 61130
Loc: gone
colmacivor here at the Campfire actually has a few .270AIs. He's probably the best source for use and experience on the round.
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#2918828 - 03/28/09 Re: 270 AI? [Re: VAnimrod]
colmacivor Offline
Campfire Regular

Registered: 02/09/04
Posts: 398
Loc: Northern Arizona
I love the 270 AI. I have other AI's but Having been a 270 fan for many years I just ordered a reamer and started to change some of my 270's to 270AI. There is more difference between barrels than one would think but a 24 is about minimum. The only 28" I built did not show a real gain over the 26". Now I have 5 pre-64 M-70's that have been on many culling trips to Africa and the performance is just great. You need to like reloading and shooting but the effort is worth it. I did kill my last two sheep, a Rocky Mt. and a Desert with the 270 AI and every thing was great. I think the 270AI has accounted for many hundred African animals from small antelope to eland and seems to do well esp with the A-frome and triple shock 140's. Will be leaving for africa again in May for culling in two countries. jm

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#2919120 - 03/28/09 Re: 270 AI? [Re: colmacivor]
cumminscowboy Online   content
Campfire Guide

Registered: 11/11/04
Posts: 3364
I don't believe the 270 win in that letter is legit, it claims a 8.8% and a 7.8% gain, I guess I will assume the 8.8% was likely with 150 grain bullets,

if you are getting 3100 from a 130 from your regular 270 win, this article claims you should be getting 3341fps from your acklyized 270, how many of you guys wanna call bull$hit on that, thats faster than the fasted 270 weatherby mag load I have listed
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#2919509 - 03/28/09 Re: 270 AI? [Re: 2Seventy]
prairie dog shooter Offline
Campfire Outfitter

Registered: 01/25/01
Posts: 8345
Loc: Texas
I believe one reason that the 270 Winchester works so well is because bullets in .277 are designed to perform at 270 Winchester velocities.
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#2920132 - 03/29/09 Re: 270 AI? [Re: prairie dog shooter]
ingwe Offline
Campfire Oracle

Registered: 12/20/08
Posts: 57827
Loc: Southwestern Montucky
Touche'


Ingwe
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#2920350 - 03/29/09 Re: 270 AI? [Re: ingwe]
colmacivor Offline
Campfire Regular

Registered: 02/09/04
Posts: 398
Loc: Northern Arizona
The bullets seem to work at 270 AI velosities as well. I used the ole 270 on 29 sheep hunts, and 50 yrs of deer and elk hunts so their is no argument that the 270 is more than sufficient. I shoot an AI now only because I want to, not because of any short commings in the parent cart. There is a gain in vel that is more than Ackley indicated probably due to superior components and measuring devices. With that said build yourself one if you want one or shoot what you have if that is your pleasure, I doubt that any game animal (shot correctly) gives a damn. jm

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#2920533 - 03/29/09 Re: 270 AI? [Re: colmacivor]
BobinNH Offline
Campfire Oracle

Registered: 01/28/07
Posts: 30701
colmacivor: What velocities do you get from the AI? I ssume you're using the 139 Swift Aframe. Has it done well for you in Africa in the 270 AI?
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#2920864 - 03/29/09 Re: 270 AI? [Re: BobinNH]
colmacivor Offline
Campfire Regular

Registered: 02/09/04
Posts: 398
Loc: Northern Arizona
BobinNH, I usually use the 140 gr A-frame, however the triple shock has done very well. I have been using 2 loads 59.3 H4831 sc at 3220 and 61 gr of R-22 @ 3250. The 110 sierra I use 61 gr H4350 @ 3500. My culling partners use a 270 and a 300H&H. I think we are convinced that the triple shock and the a-frames are very good and the Nosler part. rates right up there. We have been dissappointed in the Accubonds, sometime they work very well and other times they don't. They do however shoot very good groups. I do prefer a-frames for DG. I will be taking a 270AI and a 243 this trip, eland, gemsbok,blue & black Wildebeest,kudu,zebra, Red hartebeest, Springbok and Impala. I think the contract is for about 400 animals. jm

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#2921913 - 03/29/09 Re: 270 AI? [Re: colmacivor]
mdatlanta Offline
Campfire Regular

Registered: 11/29/05
Posts: 257
Loc: Atlanta, GA
How does the .270 Gibbs compare with a .270 AI in terms of capacity/velocity, etc.?

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#2922313 - 03/30/09 Re: 270 AI? [Re: 2Seventy]
alpinecrick Offline
Campfire Kahuna

Registered: 03/02/05
Posts: 19197
Loc: Western Slope of Colorado
 Originally Posted By: 2Seventy
I hear quite a lot about the 280, why not the 270 AI? What are the pluses and minuses of this caliber?


270



P.O. Ackely mentioned the only cartridge he couldn't get an "improvement" from was the 270.......




Casey
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#2922353 - 03/30/09 Re: 270 AI? [Re: cumminscowboy]
alpinecrick Offline
Campfire Kahuna

Registered: 03/02/05
Posts: 19197
Loc: Western Slope of Colorado
 Originally Posted By: cumminscowboy
I don't believe the 270 win in that letter is legit, it claims a 8.8% and a 7.8% gain, I guess I will assume the 8.8% was likely with 150 grain bullets,

if you are getting 3100 from a 130 from your regular 270 win, this article claims you should be getting 3341fps from your acklyized 270, how many of you guys wanna call bull$hit on that, thats faster than the fasted 270 weatherby mag load I have listed



I've chrono'ed two 270AI's on a couple of occasions (they weren't mine)--I didn't see much improvement.

I did meet a guy who 30 years ago loved necking up the 06 case--to 338, 8mm, and 35 calibers. Eventualy he started AI'ing them. He said in every instance he saw decent gains with heavier bullets, very little gain with lighter bullets. That's been my experience with my two 06AI's. But maybe the latest powders are changing that?

Regardless, I find 8% gain with a 270AI very suspect.......



Casey
_________________________


Not being married to any particular political party sure makes it a lot easier to look at the world more objectively...

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#2932690 - 04/03/09 Re: 270 AI? [Re: alpinecrick]
phillip Offline
New Member

Registered: 04/03/09
Posts: 6
My first post......
I have an .270 ackley with 25" douglass air gauged stainless barrel. What ive learned its all about powder selection like with any other caliber. nosler 140 accubond, imr 4831, fed 215, norma case gives me 3100 fps easily without pressure 10 ft from muzzle. Standard 270 fireform load was 2800 fps. I started out with some other slower powders and was disappointed with the performance.

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