243 or 243 AI

SkipB

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Feb 4, 2021
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Brooklet Ga.
I`m getting ready to rebarrel my older 243 and I am either going back with a McGowan 243 or 243 AI. Is the Ackley that much better than the standard 243?
 
Here's how I look at it. I have a few improved cartridges. So a new barrel will not reach its top speed til about 100 rounds.
So I spend that time fire forming with a full load for the parent round. Then start my load work. It will also shoot standard very well so you can use them for hunting or target if you want more brass.
I see no downside to them.
I've always wanted a .243 but when I do I will do a AI.
 
If you run Reloder 26 you can get ~3,200 fps with a 105 hybrid but it is a bit temp sensitive above ~86F in my experience. I was going to build an AI but didn't see the need with the velocity I was getting.
 
I would ask which of the two reamers can throat for the bullet weights you want to shoot, no reason to go with the AI if the one they have cuts a chamber where the bullet you want to shoot is pushed too deep into the case/jumps too far.
 
Though you may get a single digit performance improvement, the real value in a Ackley-ing a 243 / 7-08 / 308 is for the improved brass life, reduced trimming, and the "yippie" of saying that you have an Ackley cartridge.
Im too lazy to dig it out, but you can find Bob Jourdan's article where he goes over the performance benefits of Ackley-ing different cartridges.
I have a 6.5 Swede Ackley, and it does have noticeably more oomph than the standard Swede, where Jourdan calculated a 13% performance improvement. Also have a 6mm Rem Ackley in the final stages of build. At a 1:8 twist, I did that one for brass life.
 

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