How much do we really gain from the A.I. rifles.

[Wild Bill G]

Was just reading another post and have been reading my Nosler manual Is the Ackley Improved cartridge really an improvement. The 30-06 really caught my eye you only gain .3 grains of water more capacity and max loads were the same. However the Manual said the ackley version was 100fps faster how A larger case burning same amount of powder equals less pressure for less speed. Then I looked at the 280 and 280AI all of a sudden huge case capacity gain With AI and more powder used. Remember both of these the 06 and 280 are the same where did all the extra room come from with the 280. Both were using the 40 degree shoulder angle. Is the manual wrong with one of them or is there just more gain with the smaller calibers.

 

[MudRunner2005]

The .30-06 AI is way more than .3 grains of H2O capacity increase...Sounds like somebody screwed up typing or proof-reading. I won't tell you my powder charge but formed brass, 7828 SSC, Fed 210M primers, and a Berger 185 VLD seated .015" off the lands is getting me right around 3,000 FPS from a 26" .30-06 AI. That's a pretty solid gain over the standard old Springfield.

But if you want a truly huge performance increase over a standard .30-06, build a .300 Sherman. It's based off the .270 Win case, with the neck opened up to .30 caliber. It's like you took a .30-06 AI and improved it again by pushing the shoulder farther forward, and keeping the 40º shoulder.

https://www.longrangehunting.com/threads/300-sherman-vs-06.130533/

 

[Wild Bill G]

Don't you mean the 280 it's shoulder was moved ahead to prevent chambering it in the 270 I think that is how it goes. Not looking to impove on 30-06 as I have an 30-06 AI target rifle I bought years ago. I was just wondering why some of the AI cartridges gain a lot and some it appears very little. I have my 06 improved it's a 300Wby lol.

 

[J E Custom]

Was just reading another post and have been reading my Nosler manual Is the Ackley Improved cartridge really an improvement. The 30-06 really caught my eye you only gain .3 grains of water more capacity and max loads were the same. However the Manual said the ackley version was 100fps faster how A larger case burning same amount of powder equals less pressure for less speed. Then I looked at the 280 and 280AI all of a sudden huge case capacity gain With AI and more powder used. Remember both of these the 06 and 280 are the same where did all the extra room come from with the 280. Both were using the 40 degree shoulder angle. Is the manual wrong with one of them or is there just more gain with the smaller calibers.

One reason the 280 AI is much faster is because the case length to neck junction is .100 thousandths longer than the 30/06 parent case.
when you AI these cases, you don't change this dimension.
So a 30/06 AI will has a greater case capacity than the 30/06. and the 280 has more case capacity than the 30/06 due to the longer case body. And the 280 AI has a case capacity greater than the 280.

Case length to shoulder neck junction is 2.109 on the 30/06
Case length to shoulder neck junction for the 280 is 2.199 (.100 thousandths difference).

.100 thousandths is enough to render the firing pin useless in a 280 if a 270 or 30/06 round is loaded in the 280 chamber. when comparing the 270, 280 and 30/06 AIs the 280 AI has the most case capacity of all three.

The 270 Winchester is longer than the 30/06 (2.155) for the same reason, but is still .044 shorter than the 280 Remington. The 280 Remington will hold more powder than any other 30/06 based cartridge and the 280 AI is just about at the maximum case capacity for the 30/06 base case. Overall case lengths vary because of the neck length, but powder capacity is determined by case volume from the case head/Web to the neck shoulder junction.

J E CUSTOM

 

[CaptnC]

Having had one gun chambered in 6mmAI I personally don't care that much for the AI. I know that is very unpopular to say, but every AI has another cartridge that is just a little faster, so they all keep stair stepping up in speed/FPS.

But I will give credit that his design is more efficient. If your a high volume shooter it is very easy to make a case for the AI design. Especially if your using one of the overboar cartridges.

Like many have said, fire forming brass is very simple. The 6mmAI I had were easy to make.

I didn't like mine because it just didn't kill the way I had hoped. I really like Nosler BT's, but 95gr BT's just didn't work for me. Lost a deer and one hog with it in one season. I talked my mother into hunting with it. She is a dead eye shot like most women are. But they were both found the next day, but the meat was spoiled so she went back to her 7mmRM!

 

[bigngreen]

I think the term AI has become and generic term for an improved case, some may be a true ai then some may be blowing the shoulder forward and out and taking taper out to min which makes comparing ai to ai harder.

 

[MudRunner2005]

Don't you mean the 280 it's shoulder was moved ahead to prevent chambering it in the 270 I think that is how it goes. Not looking to impove on 30-06 as I have an 30-06 AI target rifle I bought years ago. I was just wondering why some of the AI cartridges gain a lot and some it appears very little. I have my 06 improved it's a 300Wby lol.

I'm not sure what you mean... No, all AI chamberings were designed to be shot using the parent case for forming. Some AI cases have different shoulder placement, it depends on where the shoulder lands on the parent case. .270 AI might have a different shoulder than the .280 AI, because the .270 Win, might have a differently placed shoulder than the .280 Rem.

Back in the day powder selection sucked, brass wasn't as pure or consistent, bullet selections were minimal, and given those factors, some of the AI's might not have been as big of an improvement back then, even so much as for P.O. Ackley himself to state the he felt some of them weren't worth it. But thanks to modern technology, some small capacity gains, mixed with better quality components, and slower burning magnum powders, we can get higher velocities with lower pressures. So, most AI's, if loaded with modern components to modern specs, can show massive improvements compared to what the old manuals show.

That's funny you mention the Wby... I have a .300 Wby improved, it's called a .300 Ackley.

 

[MudRunner2005]

I think the term AI has become and generic term for an improved case, some may be a true ai then some may be blowing the shoulder forward and out and taking taper out to min which makes comparing ai to ai harder.

Yes sir, you are correct. Prime example of your point, is that Ackley died in 1989, which was 8 years before the .260 Rem was invented? It was released in 1997, so there's no way the .260 AI is really an "Ackley" Improved, because Parker never even knew it existed. It may have been designed off the same basic AI characteristics, but that doesn't make it a true "AI" cartridge, if he himself never designed the improvements (in my opinion).

 

[gohring3006]

I tend to over engineer and then let the object cruse at working speeds. I do this with everything I use that's dynamic.
So, I think runnining something like a .280 A.I. at a velocity considered on the upper end of its parent the .280, would result in superb brass and barrel life.

 

[lancetkenyon]

Having had one gun chambered in 6mmAI I personally don't care that much for the AI. I know that is very unpopular to say, but every AI has another cartridge that is just a little faster, so they all keep stair stepping up in speed/FPS.

But I will give credit that his design is more efficient. If your a high volume shooter it is very easy to make a case for the AI design. Especially if your using one of the overboar cartridges.

Like many have said, fire forming brass is very simple. The 6mmAI I had were easy to make.

I didn't like mine because it just didn't kill the way I had hoped. I really like Nosler BT's, but 95gr BT's just didn't work for me. Lost a deer and one hog with it in one season. I talked my mother into hunting with it. She is a dead eye shot like most women are. But they were both found the next day, but the meat was spoiled so she went back to her 7mmRM!

That sounds much more like a bullet failure than a cartridge failure. I don't care for the NBTs myself. Especially at hyper velocities unless shooting them at varmints. Throw a different bullet, and I bet your results are much better. 6mmAI should rock a deer with proper bullet construction and shot placement.

I have/had or done load development on many AI or other "improved" cases. And I love them myself.

I have seen between 100 to 270fps gains in an AI conversion. Best gains I ever saw were when I rechambered a .250-3000 Savage in a 24" Rem to .250AI @ 23.5". I went from a 2900fps 100 SMK & 100 TSX to 3150 w. 100 SMK & 3170 w. 100 TSX. I also ran the 115 Berger HVLD @ 3100 after the conversion with no pressure. My second longest kill ever was that rifle running the 100 SMK @ 3150. A coyote @ 1327 yards, 2nd round hit.

 

[snox801]

Agreed that it was bullet and possibly an older one as the newer bt seem to be amazing. I use them in my 257 Roy at very high speeds. Also use them in .243 on deer and hogs never had any issue. I heard a rumor that they had issues and redesigned the bullet but I'm not sure when. I've been using them for 5 years and have had perfect luck. But again bullet not cartridge.

 

[J E Custom]

I think the term AI has become and generic term for an improved case, some may be a true ai then some may be blowing the shoulder forward and out and taking taper out to min which makes comparing ai to ai harder.

You are exactly right, normally when a cartridge shoulder is changed to 40o, It is referred to as an AI (Ackley Improved) because he was the most prolific user of this shoulder angle. He also tested many different shoulder angles and found the 40o to be the optimum angle. There are other shoulder angles that are different degrees (30o, 35o and 37.5 degrees) that are often called AIs or just Improved. Normally If a person wildcats a cartridge and changes more than the shoulder angle to 40o, It is designated by the changes (Like a 338 Lapua improved 35o) for an example.

Normally the reamer maker is required to have everything that Is different than SAMME identified on the reamer, some smiths follow this
in detail on the barrel ID. others may simply mark it as a 338 Lapua AI,

I feel it is important to note everything different in the chamber on the barrel ID for safety and to minimize confusion if someone ends up with the rifle that has to load for it.

So whether or not you call the change AI or Improved, could make a big difference. If it is simply a cartridge that has the shoulder changed to 40o without changing anything else, Calling it an AI is fine but is other changes have been made, it needs to be identified with all the changes.

Just my opinion

J E CUSTOM

 

[Wild Bill G]

I like the idea of the AI cartridges was just wondering if we gained as much as we thought we did. I believe cartridges like the 220 Swift and tapered ones like that stand the most to gain in just plain old longer case life.

 

[MudRunner2005]

I like the idea of the AI cartridges was just wondering if we gained as much as we thought we did. I believe cartridges like the 220 Swift and tapered ones like that stand the most to gain in just plain old longer case life.

Yes, removing wall taper and pushing the shoulder out to 40º makes a big difference in case capacity.