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Pressure is what you load it to.
: Original model 1886's (newer nickle steel) rifles handled the .450 Alaskan just fine with pressures well under 40,000CUP.
: Ballistics of a 400gr. bullet in the 1,900 to 2,000fps range, from a ctg. with 97gr. capacity "must" be below that pressure as the .45/70, according to Speer's manual, produce up to 1,870fps at only 28,000CUP, the SAMMI max. Interestingly enough, in their strong action data, they list the pressure at 35,000CUP at 2,132fps with the same 400gr. bullet.
; A friend of mine has the 18 1/2" Marlin stainless, and he gets 2,004 fps with Barnes original-type FN's using 49gr. Reloader#7, as listed by Speer for the lighter lever action rifles. His pressure MUST be higher than 28,000CUP due to the velocity he is getting in that short barrel. His extraction is easy, and the primers show no pressure signs of any sort(as they wouldn't at even 35,000CUP). The load appears to be quite safe for his rifle.
: Marlins are supposd to be good for over 40,000CUP, yet most data lists 28,000 as max. This, I don't quite understand. Perhaps it is due to the large size of the .45/70's case thinning the barrel's breech end in the chamber. Due to this, perhaps the .348's much larger case diameter is a poor choice for the Marlin. It's just fine, however for good M86's, especially the newer M71's- apparently as originally chambered up by Harold Johnson in Alaska (along with the .50 Alaskan).
: I chambered a Model 70 Winchester (post 64) for the .450 Alaskan, however I cut a new extractor groove and turned the rim down to .532 to fit the magnum bolt face. This round has a 97 gr. capacity whereas the .458 WM is listed at 90gr. Pressures being what you load, this round easily matches anyting the .458 Winchester can do, expecially with the overbuilt, especially strong .348 brass- IN A BOLT ACTION RIFLE. Due to being a slightly rebated rim round, I perfer to call this one the .458 Alaskan. I routinly load 400gr. and 350gr. bullets to 2,400fps for less than max loads in the bolt gun. I would not shoot these loads in a lever gun of any sort.
: Due to the .535" head dia. of the .348 brass, a Marlin probably wouldn't work very well due to it's action width being quite narrow and the resulting skinny barrel breech if chambered for this fat round.
; Picture: .450 Alaskan and .458 Alaskan.

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Daryl

"a gun without hammers is like a Spaniel without ears" King George V

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