Why no .308 AI’s ?

[Newtosavage]

Here’s another question for you rifle cartridge gurus- why don’t we ever see .308 AI’s? Did they try it and just not get enough benefit out of it?

 

[Northpark]

Probably not much benefit. It already doesn’t have much case taper and blowing out the shoulder to 40° wouldn’t add much case capacity either. Though I actually did run into a guy at the range yesterday that was messing with a .308 improved of some interesting flavor. His goal was .300 win mag velocity with 208gr eld’s if I remember right. Don’t know how successful he was though.

 

[hodgeman]

PO Ackley "Improved" virtually every cartridge in existence in his day, including the .308WIN.

But, most of them showed very little improvement (if any) over the parent case- including the .308WIN-AI.

It's arguable that the only reason the 280AI has made it commercially is that Remington neutered the original so badly out of the gate that it's one of the few AIs actually worth the trouble. The vast majority of AI cartridges are obscure today, since with modern powder you can outperform the AI with the parent case.

 

[HandgunHTR]

PO Ackley "Improved" virtually every cartridge in existence in his day, including the .308WIN.

But, most of them showed very little improvement (if any) over the parent case- including the .308WIN-AI.

It's arguable that the only reason the 280AI has made it commercially is that Remington neutered the original so badly out of the gate that it's one of the few AIs actually worth the trouble. The vast majority of AI cartridges are obscure today, since with modern powder you can outperform the AI with the parent case.

I agree with everything you said up until the last part in bold. Any improvements you get in the parent with modern powders, you also get in the AI version.
I own quite a few "AI" type chamberings as I am a looney that likes to tinker and reload. All of the TCU cartridges, a .280AI, a 7-08AI, and soon to be a .260AI. I am getting 2808fps shooting a 162 grain ELD-X out of my 7-08AI. You are not getting that velocity out of a standard 7-08 without going overpressure.
In my 280AI, I can get up to 2950 with the same bullet. That is pretty close to 7RM velocity. In my 7TCU I can get 2250 out of a 10.5" pistol barrel with 120 grain Nosler BTs. The 6TCU is pushing over 2500 fps with an 85 grain SP and a 14" barrel.
Most don't like the AI because it is "too much work", but if you are handloader, the AI version of any cartridge will give you a bit more and as a bonus, you don't have to trim brass nearly as often.

In the case of the .308AI, it really didn't get much press because the 30-06 exists.

 

[Northpark]

I’m with @HandgunHTR on this one. I only own one ai and it’s a 7-08ai. If you’re a hand loader ai can make sense. My 7-08ai drives a 140gr absolute hammer at a tick over 3k at the muzzle. My next rifle (if I don’t build a 6ARC bolt gun) will likely be a .22-250ai.

 

[hodgeman]

I agree with everything you said up until the last part in bold. Any improvements you get in the parent with modern powders, you also get in the AI version.

I'll clarify since I can see where my comment isn't very clear. You can take modern powder and get all the gains that PO Ackley promised with his original AI loads in a factory chamber. Of course, you can put modern powder in an AI and get more gains too.

Some of Ackley's cartridges see some real improvement- like the 280AI, and per your data the 7-08. The 308WIN AI is pretty negligible. I messed with a 30-30AI years ago and the gains I got didn't even remotely approach the 300 fps mark Ackley promised- more like 100fps at best. A swap to Leverevolution powder netted me 150fps without anything else at book loads in a factory chamber and I can likely run that number up even higher with judicious loading.

One benefit of the AI chamber is that it reported reduces trimming- I didn't mess with the 30-30AI long enough to see that.

 

[Gen273]

Because you can't improve perfection...

 

[crich]

I agree with everything you said up until the last part in bold. Any improvements you get in the parent with modern powders, you also get in the AI version.
I own quite a few "AI" type chamberings as I am a looney that likes to tinker and reload. All of the TCU cartridges, a .280AI, a 7-08AI, and soon to be a .260AI. I am getting 2808fps shooting a 162 grain ELD-X out of my 7-08AI. You are not getting that velocity out of a standard 7-08 without going overpressure.
In my 280AI, I can get up to 2950 with the same bullet. That is pretty close to 7RM velocity. In my 7TCU I can get 2250 out of a 10.5" pistol barrel with 120 grain Nosler BTs. The 6TCU is pushing over 2500 fps with an 85 grain SP and a 14" barrel.
Most don't like the AI because it is "too much work", but if you are handloader, the AI version of any cartridge will give you a bit more and as a bonus, you don't have to trim brass nearly as often.

In the case of the .308AI, it really didn't get much press because the 30-06 exists.

What are your thoughts on the 7mm SAW that WTO puts out in comparison to the 7-08ai?

 

[Wrench]

The 308 feeds so well in auto guns it's basically unimprovable.

I've never ai'ed that case, though I have shoved my 308 target rifle WAAAAY faster than published when chasing pressure.

I have ai'ed the 223, 260 and 30-06 and been happy with all. The ai can be fickle at feeding if all mag geometry isn't correct.....where the parents don't have the issues.

 

[HandgunHTR]

What are your thoughts on the 7mm SAW that WTO puts out in comparison to the 7-08ai?

They are essentially identical. IIRC, the main difference is the standard freebore of the SAW is a bit longer so you can seat the heavies out there a bit more.
It was also developed to use SR primered brass, but honestly, you can do the same with the 7-08AI.

 

[thinhorn_AK]

The 308 feeds so well in auto guns it's basically unimprovable.

I've never ai'ed that case, though I have shoved my 308 target rifle WAAAAY faster than published when chasing pressure.

I have ai'ed the 223, 260 and 30-06 and been happy with all. The ai can be fickle at feeding if all mag geometry isn't correct.....where the parents don't have the issues.

Pardon my ignorance, what does a 30-06ai get me over my regular 30-06? Would that require special dies and brass etc? I realize I’d have to get the rifle re chambered but what else?

Thanks!

 

[Wrench]

AI'ed cases, done correctly can fire the parent and formed case without issue.

The 06' gains some good speed with heavier bullets and the diameter makes for good feeding. Case life is improved. The dies needed are either a body die or a lee collet will work. Die sets are available as well.