I'm reading the book "White Hunters" by Brian Herne (a very interesting book) and it references a cartridge called the .285 OKH, which it says is a .30-06 case necked down to accept 7mm bullets (developed by Elmer Keith & two of his friends). Wouldn't this cartridge be the same as the .280 Remington, or is it configured differently ? Thanks for any info.

The 285 OKH is simply a .30-06 case necked down to 7mm. It has a slightly longer neck than the .270, but same shoulder angle, and was designed around using 180 gr. Bullets. It's just a 7mm/06 So, yup just a .280 Rem.

The base-to-shoulder length (headspace) on the .280 is slightly longer than the .30-06 .270 and 7mm-06, so if the .285 OKH is just an '06 necked to 7mm the .280 shouldn't chamber. Remington did this intentionally to prevent .280 rounds from chambering in .270 rifles.

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Remington did this intentionally to prevent .280 rounds from chambering in .270 rifles.

Having a look at cartridge dimensions, there are subtle differences between the 280, 270 and 30-06 that should prevent the 280 and 270 from chambering in the 30-06 and the 280 in the 270 which wouldn't be possible anyway due to the bullet being larger than the 270 throat but the 270 looks like it will chamber in the 280. Now that is odd! Remington design a cartridge that cannot be accidentally chambered in a 30-06 but don't mind if another existing cartridge can be accidentally chambered in their new rifle. But it does mean the 7mm 06 is not the same as the 280.

Like everyone else said, the OKH was a neck down to 7mm without changing anything else. The 280 Rem has a different shoulder position and neck length. It has a negligble increase in capactiy, accordingly.

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But it does mean the 7mm 06 is not the same as the 280.

Yep real darn close but not the same.

I do believe that a 7-06 would chamber in a 270 depending on where each fell in the max min range. I don't have Saami numbers maybe someone else does.

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I do believe that a 7-06 would chamber in a 270 depending on where each fell in the max min range

The neck diameter of the 280 is supposed to be 0.18mm (.007") bigger than the 270, so the case at least might be able to fit in but would the 7mm bullet go into a 270 throat? According to Howe, the diameter tolerance is ± .0005" on diameter. He gives the 280 throat diameter as being .2845". It seems that theoretically at least, the 280 bullet should not be able to fit the 270 throat? Howe does not give the 270 chamber dimensions. He does seem to have an error in the 303 British dimensions!