Ackley improved

White Eagle

White Eagle

New member
If I were to go from a 280 rem to a 280 AI would I still be able to shoot factory 280 rem rounds thru it to get fireformed cases?????What kind of velocity increases are there to be expected........ /ubbthreads/images/graemlins/confused1.gif
 
Yes..you would be able to shoot factory 280 Rem cases in an Ackley chamber. That's one of the benefits of the AI process.

Properly done, an AI chamber has a slightly shorter head space measurement than the parent case has by a couple thousandths of an inch.

If you plan to use the original barrel, the only way to properly have an AI chamber cut is to have the barrel set back at least one thread so the slightly shorter AI chamber can be cut properly. Not setting an existing barrel back will result in nothing but problems in the future if converted to AI.

HTH - BCB
 
White Eagle,
Yes you will be able to fire standard 280 ammo and assuming you dont use an excessively lite bullet, you will eject 280AI. As far as velocity increase you can expect an additional 150 fps. This is a reasonable number. I shot my 257 AI this very day. I own several in differant calibers.
 
if your gunsmith followed the book you can shoot factory ammo in it. thats one of the positive things about ackley improved.

with 160 gr bullets you should see about 250fps second gain in velocity which is true of most ackleys. they don't give you blazing speed, just a modest increase.

i have 5 ai's and love them all.

good luck.
 
Certain calibers benefit from the Ackley Improvement. The .280 has a strong following in that dept. Some of the other more mentionable improvements are the 22-250/250 savage as they have tapered cases and really gain powder capacity. You may limit your resale of the gun if you are not planning to keep it.
 
Factory ammo fired in the AI chamber will show a small reduction in velocity, because some of the force will be used to expand the case.
Mark
 
I just start working with a new 22-250 AI....rebarrel job. Previously the gun was a 22-250.

22-250 max load of RL-15 50 gr. Vmax 3840 fps

22-250 AI max load of RL-15 50 gr. Vmax 4100 fps

By no means scientific but using proven pressure indicating methods and common sense this is what I came up with to date.
One of the benefits of the AI is that fireformed correctly the brass lasts much longer because it doesnot stretch nearly as much in subsequent firings.
 
There in lies yet another question???? How do you proceed with the max load levels ? Do you increase by a certain percentage or is there a manual for the Ackley cartridges???
 
i load 60.0gr IMR-4350 CCI 200 primer 145gr Speer FBSP in my rem 700KS custom shop w/24" barrel. i see no need to go AI with a 280rem. it is a great caliber without going AI. you really don't gain much at all by going AI with the 280rem. i got my first one the year Rem came out in M700 7MM Express.

get a set of PO Ackley manuals for all his improved's and more.

i increase loads by 2.0 grains in this size case until i start to see pressure signs. look in a Hornady manual to see what charges give which velocities and they increase about 2 grains at a time.
 
To start the process you first fire a standard 22-250 in the chamber.....preferably handloaded with the bullet jammed into the rifling. This gives best case forming results. I then use max 22-250 load data and work up .5 grain at a time. My old Nosler manual has load data in it for the AI. You can also use data for a .220 Swift with excellent results. Besides a small increase in bullet speed you get much better case life and reduced back thrust (less wear and tear on the gun).
 
Quote:
To start the process you first fire a standard 22-250 in the chamber.....preferably handloaded with the bullet jammed into the rifling. This gives best case forming results.



If the AI chamber has been set up properly, jamming a bullet into the riflling is not only un-needed, it's not desirable.

A properly cut AI chamber has less headspace than the factory round, and the factory case should chamber and close on the bolt with slight resistance, thus insuring proper head space on the cartridge for fire forming.

Jamming a bullet into the lands may distort the brass case somewhat prior to firing and create undue and un-needed stress on the cartridge case.

-BCB
 
Jamming a longer case than the chamber is cut wouldn't distort the brass even worse.....esspecialy a piece of brass that doesn't match the new chamber yet ?
 
Quote:
what is ackley improved? i am new to custom side of shooting



for simplicity purposes ackley improved is nothing more than taking a factory case ie: 30:06 and straightening the side walls and pushing the shoulder forward and giving it a 40* angle. it is usually about a 5-15% increase in powder space depending on which case you are improving.

increasing the shoulder angle also decreases bolt thrust. this is a reason most short magnums and ppc cartridges are popular.

the best way to be informed about ackley cartridges is to purchase the 2 volume set of ackley books. there is much to be learned from them, even though they are old. mr. ackley reached his heyday in the 40's through the 60's. in my opinion he was a genius. other people have different opinions.

i never met an ackley cartridge i didn't like.
 
Rick Jamison had a good article in shooting times magazine comparing the 30/06 and a 30/06 AI. He used the same rifle and mounted a pressure gauge to the gun and then developed loads for both staying in the same pressure ranges.

It kinda took the "Improved" out of the idea for me. If there is no more improvement in a 280 AI vs 280 than he got with the '06, then it is simply a grand waste of your shooting dollars IMO.
 
skb2706:

To answer your question, the answer is no. By letting the slightly shorter chamber (by @0.002") determine headspace, you actually put less backward pressure on the case than you do with having a bullet jammed into the lands pushing back on the entire case/shoulder/neck area.

The idea of jamming the bullet into the lands to fire form an Ackley round came about when some folks went the cheap route to an Ackley chamber and just ran an AI reamer into an existing standard chamber to get the 40 degree shoulder. What they actually got in that case was a chamber that was slightly too long, and the only way to attempt to set proper headspace on the case was to jam a bullet into the lands to force the face of the cartridge back against the bolt face.

That's why setting a barrel back at least one thread is the only correct way to go from a standard case to an AI case; ie 257 Robt. to 257 Robt. AI.

Again, if the AI chamber is set up correctly, jamming a bullet int the lands is not only not needed, but it might also create some unnecessary case stretching upon firing.

Like was mentioned above, reading the 2 Volume Ackley Handbooks is a good primer on the subject. PO Ackley never saw improving a cartridge for extra velocity as a reason to do it. He was interested in lessening rear bolt thrust at firing (straight case walls) as well as attempting to direct unburned powder into the center of the barrel (40 degree shoulder) and away from the throat area of the barrel as reasons why he developed the concept. Increased velocity was just a natural result of increased case capacity

HTH -BCB
 
So then what I have concluded is that Ackley chambers are More efficient,better on brass,have less back thrust,and have more velocity.What could be better?????
 
BCB - thank you for the info. I have only worked with two AIs. First one is a 6mm 30-30 AI for which there is no real parent case for ....at least in the Ackley sense of the word. The other is my new 22-250 AI which is not a re-cut chamber....it was originally cut to AI specs. IT is slightly shorter than my previous 22-250.
 
skb2706:

I'm glad the info. helped. /ubbthreads/images/graemlins/grinning-smiley-003.gif

I've played with several of them over the years but currently only own one AI rifle. It's a 257 Roberts AI built quite a few years ago on an FN Belgian Commercial 98 Mauser action with a Douglas barrel.

I doubt that any animal could outrun the standard case versus an AI case with a little more velocity, but I actually like the AI cartridges for their looks as much as anything else.

But that's just me.... /ubbthreads/images/graemlins/laugh.gif

Take care. - BCB
 


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