.308 Win AI

[lgm270]

Anybody tried the .308 Winchester  AI? I was thinking of trying it in an old .308.  Would like your imput.
 

[Reed1911]

What are you trying to achieve and which old firearm? Some will not feed the AI style case very well, and some will gain little benifit from the conversion.

[Catfish]

I would not mess with it. Where you get gain from the AI is straighting the case and blowing out the shoulder. You won`t gain enough by AI`ing the .308 case to get much increase in velosity. This comes for an Ackley fan, but the .308 is just not a good choice in my oppenion. But to each his own.

[lgm270]

I saw a pic on line  of a 308 AI and it looked pretty sexy.  I don't anticipate a huge increase, but I have read that you have less case stretching and less backthrust.  Why do I want to do this?  Just because.  I am curious about how it would work out. 

[Reed1911]

In most AI conversions you do reduce the backthrust with the AI case (obviously it is not as reduced with the original case, but still some as the pressure would be reduced). Sexy, amen (all of them are). Case streching is relitive, neck sizing only on any case will reduce the strech and most people compare the amount of strech between fl sizing the parent and neck-only on the AI. Accuracy is also usually improved, sometimes only due to the now custom chamber and in some case also due to the case design. Feeding can be a pain in many automatics, but most bolt guns do fine.

[Lone Star]

....Case streching is relitive, neck sizing only on any case will reduce the strech and most people compare the amount of strech between fl sizing the parent and neck-only on the AI.....

Most case stretching is due to a miss-match between chamber and die dimensions.  A large chamber and tight dies means the case is squeezed radially, and the only place the displaced brass can go is into the neck.  With a properly-chambered rifle and dies cut for the chamber, stretching will naturally be reduced even in high pressure loads.

As for reduced breech thrust, this is good Madison Avenue advertising but doesn't hold up to the thinking shooter.  The idea is that the case walls will grip the chamber and not let the case head slam into the breech.  But wait - the last time I fired a case with short headspace in a rifle with long headspace - the case walls stretched and the case head hit the breech!  The fact is that the brass case is the weak point, and it is well proven that it will stretch even though the case walls are held in place.  Result - full thrust is applied to the breech.  Nice idea, but no go.


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