What is Ackley

[iracecars4fun]

I have started to reload and have a basic understanding of the process and gunsmithing terms and such but something i dont understand is the difference between a regular cartridge and an ackley one, does it apply to all cartridges or just some. Additionally what is AI, or are they the same thing?

thanks

[Generalpie]

Ackley was a gunsmith who kinda made a name for himself by opening up the chambers so the ammunition could be made by fireforming. Basically making wildcat cartridges easy to deal with.

AI is Ackley improved which is what one of them is usually called. i.e. 30-06 Ackley improved.

The AI rounds and the parent cases are not interchangeable.

[iracecars4fun]

so if im understanding this right an ackley chamber is slightly larger than a regular chamber, and the goal is to use a regular cartridge, fire it in the AI chamber and then reload it without re sizing?

[jmart]

so if im understanding this right an ackley chamber is slightly larger than a regular chamber, and the goal is to use a regular cartridge, fire it in the AI chamber and then reload it without re sizing?

I'm pretty sure die manufacturers sell AI dies, at least Redding and RCBS. But you're right, to get the case to begin with you use the parent case and fireform it in an AI chamber. Then it's either a neck sizing operation or a FL resizing operation, as needed.

From my recollection, when loaded to similar pressures, the AI chambers didn't allow significantly greater velocities. If old P.O. Ackley was seeing big velocity boosts, he was loading those things stinking hot.

[chadbag]

IIRC, most Ackley cartridges were trying to get more powder volume in a case by changing the angle of the shoulder (pushing it up so that the slope was less, hence more case volume).

[Generalpie]

You are half right. The ackley cartridges usually just increase case size and you can fire form the brass. You still need to resize for regular loadings, either full or neck only.

Essentially they are two different calibers all together and load data, etc isn't interchangeable. They are related in the same way a 7mm/08 or .243 is related to a .308.

[RyanB]

In most cases they are 100 fps faster than the parent cartridge at equal pressure. Sometimes more, sometimes less. Cases with excessive taper, like .300 and .375 Holland and Holland, can gain a lot more. Think 200-300, basically equal to the Weatherby equivalents. In some rimmed cases Ackley also moved the shoulder forward, and that version of the 30-30 is also dramatically more powerful. AI cartridges show less pressure signs at equal pressure so people often load them hotter than they think they are. They also resist case growth much better than standard cartridges, and in some calibers people will cut an AI chamber just to make brass last longer between trimming.

[kartoffel]

If old P.O. Ackley was seeing big velocity boosts, he was loading those things stinking hot.

If I recall the loads for .257 Roberts and Roberts AI that I've looked at, the Ackley version was loaded to a higher pressure. Of course, it's probably not safe to assume that *all* AI cartridges are rated for higher pressures. Heck, some of the more obscure "Ackley" variants may not even have a SAAMI rating at all.

But yeah, .223 AI and .257 Bob AI are higher pressure than their non Ackley cousins.

[nineteenkilo]

P.O. Ackley, for the most part, was noted for changing the shoulder angle of most cases that bear the "AI" marking. A few cartridges changed through this method noticed significantly better performance though most were negligible at best.

As previously stated, the 257 'Bob' was one of the better ones.

FWIW, you can fire almost any standard ammo out of AI chambers, but not vice versa.

Having reloaded for several different AI chambers over the years, my personal experience tells me that the AI is rarely worth the effort.