450 Alaskan AI case capacity

[1972RedNeck]

Anyone know the water capacity of 450 Alaskan Ackley Improved cases? And at what length?

450 Alaskan is supposedly around 88 grains. Just wondering how much of an increase the improved version offers.

[AJMD429]

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Not seeing anything on my usual source (AmmoGuide.com).

Here is some cool history on the 'Alaskan' cartridges I came across though...

"In 1952, Harold Johnson of Cooper Landing, Alaska, wildcatted the 348 Winchester by necking it up to 458, then straightening the case walls by fireforming. He called his wildcat the 450 Alaskan, and chambered Winchester Model 71 rifles for it. His initial rifle was a Winchester 1886 in 45-70. Harold cut the barrel to 20" and loaded a 400 grain bullet over a stiff powder charge. He corresponded with Elmer Keith about necking up the 348 to 458 and blowing out the case to increase powder capacity. Keith said it sounded like a good idea.

Bill Fuller made the reamers. John Buhmiller made the barrel. Frankl Barnes made the bullets, which were .032" jackets for Alaska and .049" jackets for Africa. These 400 grainers were loaded to 2100 fps at 3937 ft-lbs.

Johnson sold these converted Model 71 rifles through his gunshop, and they were stamped JKR, which stood for Johnson Kenai Rifle. There are many Model 71's that are chambered for the 450 Alaskan, as well as the less common .450-348 Ackley Improved, and the 450 Fuller, based on the 450 Alaskan.

Now, as if that weren't enough, Harold Johnson wanted more power in a lever gun. Harld took an old 50 BMG barrel and fit it to a Winchester Model formerly in 50-110 Winchester. This makes a natural conversion, since the rim and initial body of the 348 and 50-110 are the same. The 348 was necked up to 50 cal, and the case was fireformed with a slight taper.

Harold then took 720 grain 50 BMG bullets, machined the nose off, and loaded them backwards in the case. The base was not the nose, which was now a truncated cone. They weighed 450 grains. No animal on the planet could stop the steel core, or even deform it."

[samsi]

A guy messing with one on the Fire some years back claimed a 4% increase in capacity, so going by the Barsness 1/4 Rule that equates to something around a 1.25% velocity increase. Not enough to be worth the hassle IMHO, but I don't shoot many 2000 fps loads in mine to begin with. It's a lot more fun with cast at 1800-ish.

[Rimfire McNutjob]

As I recall, the 450-348 AI had much less taper and even Ackley thought it was not as reliable feeding in a lever action. Fine in a bolt gun probably ... or a Ruger No. 1.