what's the difference between Ackley Improved and A-Squared modifications?

Many "improved" cartridges are called "Ackley Improved (AI)", but strictly speaking, an AI cartridge maintains the location and angle of the shoulder juncture such that a chambered non-AI cartridge (e.g. 7X57 in a 7X57 AI chamber) maintains headspace and can be used if wanted for hunting, and/or to fireform it. Most improved cartridges do not have this feature (aside from rimmed cartridges).
 
so you're saying that everything is about the same on an AI, but for the shoulders, which are squared off for more powder capacity?

would that be similar to what this fellow did to create what is called the 6.5 Grendel Max, where they get to use all the same reloading dies and such for the standard Grendel?:
http://www.65grendel.com/forum/showthread.php?13466-6-5-Grendel-Max
 
Mr. Friendly said:
so you're saying that everything is about the same on an AI, but for the shoulders, which are squared off for more powder capacity?

would that be similar to what this fellow did to create what is called the 6.5 Grendel Max, where they get to use all the same reloading dies and such for the standard Grendel?:
http://www.65grendel.com/forum/showthread.php?13466-6-5-Grendel-Max
Click to expand...

In this example, the 6.5 Grendel shoulder is SHORTER then the max.

With wildcatting, you really need to see the chamber print or a formed case vs the parent case. In ALL instances, you are tweaking the case shape for some gain (perceived or otherwise).

The most common is to increase the shoulder angle, reduce the body taper but retain the parent case headspace... this is what PO Ackley popularised

Then there are many other wildcats that move the shoulder fore or aft from the parent case location... this is what is going on with the Grendel vs Grendel Max.

So please do not assume anything on a wildcat chamber... confirm the dimensions before pulling the trigger. Some are different enough to allow the parent case to rupture if not properly set up.

Once you understand how cases are formed, wildcatting is alot of fun and allows you to manipulate cases....

Jerry
 
hey MP, I was only using an example of what I had read previously to try help me understand what was being said in the first responses.

does anyone have a good image to share that clearly shows the difference between a standard cartridge side by side an AI and AS variant as well? a lot of pictures I have looked at have a lot of glare from the flash or whatever, and washes out my ability to really see/sense the differences.

also, MP, the fellow with the Grendel Max uses the same loading equipment as the classic cartridge. how would that be possible with the Max, if it's shoulder is blown out in such a way as to make it longer. would that not stop the die cold?
 
A Square was a rifle company that legitimized a few wildcats and modified a few cartridges, but that wasnt its forte. Started by Art Alphin (hence the name), who had some ideas about stock and cartridge design for mostly boomers. Interesting guy, i met him in kentucky a couple decades back. You should read his loading manuals, very interesting reads. Ackley was a gunsmith who modified a lot of different cartridges, but is generally known for reducing body taper and changing the shoulder angle to 40 degrees to increase case capacity. Hope that helps some. - dan
 
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