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Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by the11car, Feb 8, 2012.
what exactly does this change in a given caliber?
The best of my understanding is the shoulder angle of the case!
Fireforming a case to an Ackley Improved reduces the body taper of the case and blows the shoulder out to a 40-degree angle. There is an increase in powder capacity of from both and the total increase depends on the cartridge.
Left fire formed 220 swift AI
Right standard swift case.
AI cases are damn sexy.
Most are based on factory calibers that would allow you to also shoot off-the-shelf ammo in a pinch.
so a barrel has to be re chambered? looking at some ballistic charts i've seen it makes alot of difference... thanks for any info
I've thrown this photo up before on other posts, but it applies to this thread as there are 3 AI Cartridges in this photo. Left to right and for refrence, cartridges are : 7mm STW, .30-06 ACKLEY iMPROVED, 6.5-06 Ackley Improved, .243 Ackley Improved, and the .243 Winchester.
Hope this helps,
I might add that, not only do we get more velocity through the added powder capacity, but we also don't have to trim the cases as much or as often. The recuced taper and sharper shoulder angle seem to greatly reduce case stretch from repeated loadings.
For a performance comparison, my 243 AI has slightly more capacity and velocity than a 6mm Remington. I chose the 243 AI over a 6mm Remington because better brass is available for the 243 and the case is shorter making it easier to fit VLDs in the magazine.
I have over 5 reloadings on my 243 AI brass and my cases have not grown in length at all.
The only draw back to an AI caliber in my opinion is that it may have a harder time feeding in a repeater. A good smith can play with the feeding ramp to reduce those chances but it would be the one draw back. I had a 25-06AI built on a Rem700 that would not feed worth a rats azs....it is now gone.