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Old August 16, 2014, 08:34 AM   #1
std7mag
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Yet another Ackley question....

Looking to make the Stevens 200 (7mm-08) into an Ackley Improved.

But is it worth doing?

While maximum velocities are increased, does it change the harmonics of the barrel.

For example.

Mine as mentioned is a Stevens 200 in 7mm-08 with a 22 inch barrel.
I found my accuracy load using 41.4 gr. of Reloader 17 with Hornady 139 gr. bullets.
This is the most accurate load for this powder and bullet.

By changing to the Ackley, will this change the harmonics of the barrel, hence using a larger powder charge, or would it still be the same 41.4.

Yes, I know this is way on the low end of the scale for this powder, but still within it's "tollerance".
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Old August 16, 2014, 01:55 PM   #2
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Will you have to work up a new load?

I would say yes. Ackley is, in many ways, superior to the parent cartridge and worth doing if you are someone who is an avid reloaded.
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Old August 16, 2014, 07:21 PM   #3
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You'll be using more powder in an Ackley...maybe even a different powder...

But yes...the conversion is worth it in my opinion...any gain in velocity with equal accuracy is worth it.
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Old August 16, 2014, 07:48 PM   #4
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But am I actually gaining more velocity?

While the Ackley casing has a larger volume, which would lower pressure/velocity given the same powder charge, would using more powder to get the same pressures equal more velocity?
Or am I just burning more powder?

See where I'm going with this???
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Old August 16, 2014, 07:52 PM   #5
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The benefit of the Ackley isn't efficiency...it is increased capacity and velocity.

This does require more powder to be used.

But yes, at equal pressure the Ackley will be faster due to burning more fuel...like the old hot rod saying goes, there is no replacement for displacement.
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Old August 16, 2014, 08:12 PM   #6
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Not worth it IMO for velocity gain, you're not going to increase the case capacity enough to see any significant increase in FPS. It takes on average a 10% capacity gain to get 1-2% velocity gain. What you will gain is less case prep at the reloading bench. No more trimming due to case stretch is what you'll gain.
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Old August 16, 2014, 09:04 PM   #7
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Even if its only 75 fps...thats still an increase in velocity, plus the lack of case prep work.

That said...you may want to consider the trouble of having dies made.

Last edited by Ridgerunner665; August 16, 2014 at 09:16 PM.
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Old August 16, 2014, 10:37 PM   #8
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75 fps isn't a worthwhile gain it does nothing for trajectory and wind bucking ability in the long run. It doesn't even gain you 1 MOA of difference at 1000 yards in elevation or windage, and on only gets you FOUR yards more point blank range. If you want a real gain you have to burn more powder than what the AI will get you in a modern case design like the .308 Win and its offspring.

If you want more speed and better trajectory it's time to swap the barrel and drop caliber to 6.5 or 6mm. Not only will you be able to get more speed you'll generally get better ballistic coefficients as well. The only other option is to change your bolt head and magazine then ream it to a WSM, or sell the rifle and get a long action to run a larger case already chamber in the cartridge you want. That is the only true way to improve the ballistics of the 7mm-08.

The only benefit the OP will see is at the reloading bench. If he can't reach top end loads accurately already, more than likely the AI chamber will have the same issues if he just reams a new chamber in an old barrel. For the gunsmith in costs and the price of reloading dies the OP wouldn't be far off the cost of a new pre-fit barrel for his Stevens.
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Old August 16, 2014, 10:48 PM   #9
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I would not worry much about barrel harmonics, if you are going to a custom barrel, just get the heaviest contour you can handle. Heavy is better for stiffness.

Very few of the Ackley wildcats have survived to date, there is a 280 AI that apparently is a good cartridge, but the rest have proven either to be less inaccurate than the parent cartridge or the velocity increases not worth the bother. Ackley claimed huge velocity increases, but he only got them with huge pressure increases. On some of his velocity claims, I don't see how he could have got them without the cartridge running at 80,000 psia!

The 7mm 08 is already quite straight and I am of the opinion there is very little that can be done to improve the current configuration. If you do the 7mm AI, please come back and publish your velocities and accuracies.
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Old August 16, 2014, 10:55 PM   #10
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The AI thing is just fun and no other benefit. I fell for it and am trying to sell a AI rifle at a dealers.

Instead shop for a better rifle chambered for another cartridge. The Savage is fine but it's just an entry level rifle.
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Old August 17, 2014, 01:08 AM   #11
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^^^

The AI is a hobby. I considered it for several rifle cartridges (.270, .280, .30-06, etc.). It is hard to imagine a difference in effectiveness of an AI and a standard factory cartridge (hand load or commercial load). The change in trajectory is probably too small to increase the effective range of hunters who are not expert bench rest shooters. I am not critical of those who reload AI but I doubt if superior performance as a hunting cartridge in any caliber could ever be shown, much less proven. Nevertheless, I would welcome a left handed stainless steel bolt action rifle with a 24" barrel chambered in .280 AI and factory brass in .280 AI - in my opinion an ideal hunting rifle for North America (except, perhaps, Alaska bears.)
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Last edited by lefteye; August 17, 2014 at 01:23 AM.
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Old August 17, 2014, 01:13 AM   #12
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Probably cheaper and far easier to just buy a 280.

To rechamber you will need to buy or rent a chamber reamer. $45- $165

Then you will need to buy dies. $65 to $110
Then if you don't have access to a lathe, you need to hire the services of a gunsmith or at least rent machine time to do the work yourself. That will cost you at least 1 machine/hour and maybe two. I can't say what other smiths charge but I do such work for $75 labor plus any parts necessary, but I know many others charge around $200 labor alone.

You will need a barrel nut wrench and a set of vice blocks to hold the barrel, or an action mandrel, to remove the barrel from your Savage. More money there is you do it yourself.

If you were to sell your 7-08 for just $225 and add the amounts listed above, (say about $200) you can just buy a new Stevens in 270 Winchester, or if you love speed buy a 7MM Mag.

If you love the 7mm bore size more then the .277 bore size you can even buy a 270 or 30-06 and rebarrel it with a drop-in barrel available from barrel several makers, and then sell the new factory barrel for about $80 to $100 so to get what you want ballisticly would not cost all that much.
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Old August 17, 2014, 03:02 AM   #13
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lefteye,
Nosler offers some of their rifles with the bolt on the wrong side I believe...not stainless, but CeraKoted...probably better than stainless.
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Old August 17, 2014, 05:49 AM   #14
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My first AI I had barrel set back and new chamber cut and I had some published loading data which I used. My accurate load was different bullet/powder and I did get a gain in velocity.

Hornady load of 41.3gr/R-17 with 139gr has published velocity 2400fps and that's from test rifle with 24" barrel T/C Encore for the 7-08.

I'm not sure how many loads you worked up but I would try finding another load vs AI or buy a box of factory 140gr see how accuracy is and velocity. Accuracy first but you want velocity and I would want to higher velocity before I AI that case.

You look at max load of 47.1gr/R-17 @ 2800fps with 139gr bullet and if you AI the 7-08 you would may gain 3.5gr H20 appr.

I'm shooting 5 AI now one is SAAMI spec 280AI. I start with published data for the parent case and I use a start load and most times I'll in increase in velocity with those up to max load.
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Old August 17, 2014, 06:40 AM   #15
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Lefteye,

We just went over this in another thread, the load data and factory loads of the .280 are hamstrung by the SAAMI specifications stating max average operating pressure is 60,000 psi. If you properly work up hand loads a regular .280 is usually less than 100 fps behind the .280 AI. There is no reason a .280 can't operate at 65,000 psi like the .280 AI. If you really want a .280 AI pick up a LH Savage and order a new barrel with a SAAMI spec chamber as there are several different versions of y he .280 AI out there.
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Old August 17, 2014, 09:19 PM   #16
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Thanks guys, but I am nearly 68 years old and already have too many firearms. If I go on another western hunt I will take my LH .270, LH 7mm Rem Mag or LH .300 Win Mag. And I have 4 LH bows. BUT -- I shoot left handed because I'm left eye dominant, not left handed.
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Old August 17, 2014, 10:55 PM   #17
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Too many rifles? Is that possible?

Back when Ackley was making improved rounds, many of the rifles that shot the unimproved rounds couldn't take the higher pressure and the factory loads for them were all loaded to low pressure. The .257 Rob was the most notable for this. For other rounds the improved shoulder is mostly increases brass life.

Tony
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Old August 18, 2014, 07:11 AM   #18
Savage99
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Tony,

How does an improved chamber increase brass life?

S99
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Old August 18, 2014, 11:48 AM   #19
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It slows the forward flow of brass on firing. It's pretty simple and well noted...

Tony
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Old August 18, 2014, 12:11 PM   #20
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The sharper shoulder does increase brass life, but only if you neck anneal now and then.
About every 8 shots is good. If you do that the brass life can be about 2X more than a standard shell.
The brass on a standard shoulder flows forward easier than it does around a 38 or 40 degree shoulder but the splits you get in the neck are not affected by the shoulder angle.

In my 44 years of gunsmithing I have made many Ackley Improved chambers. If I made a guess I'd say about 75 of them. I have a lot of experience with them and I had the honor of meeting old man Ackley in person and having some long conversations with him.

But today I believe A.I shells are a tinkers delight. Something to play with because we like to play.

The “reasons” for doing AI chambers are largely a thing of the past. Those reasons are now all covered by factory rifles and factory chamberings. AIs can still be fun, but if you like to site brass life as a reason remember the cost of the dies and the reamerand the need sometimes to open up the feed rails to m,ake them work (paid for by you) and compare that to the price of just buying 2X the brass in a 25-06. Standard chamber from the factory and a set of $32 dies and your set for the life of the barrel.

The most important focus P O Ackley had in his early experiments was to duplicate 25-06 and 6.5-06 ballistics (before the 25-06 was a factory round) when there were hundreds of thousands of KAR length Mausers available very cheaply. The KAR was a shorter magazine and Ackley wanted to use the standard 57mm length Mauser shell as his base case. The AI experiments were done with about every shell at one time or another, but for the most part the 2 that were the greatest success were the 257 AI and the 6.5 AI

Now days you can buy a 25-06 over the counter as well as a 280 or a 270 and buy the lower prices rifles for less than you can buy the parts to do a Mauser in an AI shell without any rework of the action to feed, no custom dies and no custom chamber reamer.

If you like to tinker and you do the work yourself the AI can still be worth your time and efforts but if you are paying a gunsmith to do it for you, you are going to pay a LOT more money to get the same ballistics you can get with a 25-06 by building a 257 AI. And you will get a bit less than a 270 Winchester will give you if you have a 6.5 AI made.

The days of the $30 surplus KAR are long gone. I still prefer the old M98 action over all others for my best custom bolt guns, and I will still build on a good KAR or a GEW, but the idea that the AIs are going to be something special is really not true. It’s fun, so if you like them, use them. But if you are looking for a faster bullet there are a lot of easier and cheaper ways to go.
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Old August 18, 2014, 02:51 PM   #21
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Tony,

What happens if there is a "Forward flow of brass" ?

Where does the 'brass' come from?

S99
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Old August 18, 2014, 03:18 PM   #22
taylorce1
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Quote:
Originally Posted by Savage99
Tony,

What happens if there is a "Forward flow of brass" ?

Where does the 'brass' come from?

S99
You've never seen the ring around brass that shows case head separation? When a case flows it moves from the base up or at least from somewhere on the body forward. On belted magnums it's usually in front of the belt. When you full length resize to move the shoulder back you actually force the brass up the die into the neck, that is why you have to trim. Anyway here is a link to show you pictures of brass separation.

The removal of body taper and the sharp shoulder actually cause the case flow from being fired to slow down significantly. Case taper and shallow shoulder angles was a leftover byproduct of old style gunpowder that was temperature sensitive. The shape of the case aided in extraction since the tapered body and shoulder reduced the amount of bearing surface on the cartridge if a case happened to be over pressure due to the temperature. Just take a look at the old H&H cartridges and a lot of the old rimmed cartridges and the amount of taper on the bodies and shoulder.

As gun powder became less temperature sensitive you started to see a decrease in taper of the body and shoulder allowing for more powder in shorter cases. By the time P.O. Ackley started doing his research powders were far less temperature sensitive than the old nitro cellulose powder used in the H&H and the first smokeless cartridges. He also claimed that his lack of body taper allowed his cartridges to be ran at higher pressures as well, again because of the bearing surface of the brass on the chamber.
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Old August 19, 2014, 07:58 AM   #23
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Kenny Jarrett owner of Jarrett Rifles did the Introduction Article for Nosler Manual #4 on the 280 Ackley Improved published 1996. In the article he talks about his dealing with P.O. Ackley and 280 Improved and how it he decided build his first one 1979.

In his conversion with Ackley, Ackley had no idea who did the first 280AI and Ackley's version was 30-06x7mm which is in his Ackley's book along with 280 version.
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Old August 19, 2014, 06:27 PM   #24
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I plan to have a single shot .30-30 reamed to AI for a couple reasons one is for longer brass life and the other is it's my only single shot .30-30 and it will make rounds loaded for it obviously different so they won't end up in my 94 Win after I'm long gone...

I also have plans to rebarrel a Savage 110 to .338-06 AI. The barrel is available and I can install it myself. Yes dies are more expensive but I plan to neck size only and a custom set of Lee collet dies isn't that bad. I want this caliber for elk hunting here in Oregon. My main reason for this round is I don't want to deal with reloading belted magnums and a .338 Win mag is a more than I need anyway.

I think Savage rifles and now Remington ones with the barrel nut are going to be real popular for cheap custom rifles.

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Old August 21, 2014, 09:41 AM   #25
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I find the so called AI chambers worthless in terms of longer case life.

Brass fails for me when the neck wears out or splits.

I never have failures at the expansion web unless of course the FL die is set wrong or the chamber has excessive headspace.

AI chambers are a waste of time and money and hurt resale value.
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