.It has the more modern case design with more practical fit in stdM98, so why did they opt for the long .300H&H and .375H&H?
...why not just neck the .275 case to .30cal and .375cal?

The .275 Belted Magnum case is 2.50" long with a standard magnum rim diameter of .532".
There was also a rimmed version [.275 Flanged magnum], intended for use in single shot and double rifles.

According to P.O. Ackley (as quoted in the 9th Edition of Cartridges of the World), a 160 grain bullet can be driven to a MV of 3050.
If necked to .30 cal, you would probably achieve simliar vel. with 180gn.

.

You asked a question that lots of people have THE ANSWER to. THE ANSWER varies according to whom you ask.

Why did H&H go from sharp "modern" sholders to gradual, sloped, shoulders in some later cartridges? Lots of possibilites. A few are:

1. Long smooth cartridges "look" more powerful. Looks sold then, just as they do now.

2. Some of the gurus of the day felt tapered cartridges were THE ANSWER to assuring easy extraction of fired cases from what were then considered high pressure loads.That "knowledge" sort of predominated in the popular mind UNTIL the days of Ralph Waldo Miller, Roy Weatherby, P.O. Ackley, et. al., who sort of started the "modern" sharp shoulder trend with their "discovery" that straight case bodies with sharp shoulders grip the chamber better to prevent higher bolt face loads, then on spring back after firing will literally "fall" out of chambers because their sharp shoulders and lack of taper has prevented their being wedged in by the firing pressures.

Sort of "back to the future", with the modern sharp shoulder school being pretty much a duplicate of the really early sharp shoulder designs.

3. Perhaps it was easier to make long tapered-shoulder cartridges feed reliably...pretty important with what were then often considered pretty strong stuff for dangerous game.


Which is more correct approach for handling high pressure rounds well? Danged if I know for sure but I have been wowed by the logic of both the sharp shoulder and shallow shoulder approaches at different times in my shooting life. There are "True Believers" (a la Eric Hoffer) in both camps who will tell you very firmly why their way is the only correct approach.

Pick yur own pi'zen.

I wonder if the .300 Hoffman is the equivalent of the .275 opened up to .300.
I have a lot of .300 Hoffman ammo with proper headstamps and a nice sharp shoulder.
When was the .300 Hoffman developed?

Huvius,

the .275H&H is also known as the .275 Hoffman magnum.

.300 Hoffman,


of interest also is the .33 BSA [or .33 rimless NE]

quote:

Originally posted by ALF:
Necked to 375 cal ?? Why on earth would you want to ? less capacity less velocity than the 375 H&H ? There are already very capable cartridges out there doing just that.

I gather .275H&H necked to .375 cal, would be similar in cap. to 9.3x64, and like the Brenneke an easier fit into stdM98 than .375H&H, sounds like a good idea to me, had H&H gone and done it.
The drawback would have been the performance limting old technology cordite propellant the Britts were using.

.

Funny how what you think you have can have a little twist to it...
What I thought were 300 Hoffman cartridges in Hoffman boxes are actually .270 wildcats based on Hoffman brass.
I thought the bullets looked a little small for a .30 but never measured them and didn't notice the writing on the bottom of the box.
I don't know what the modern equivalent of this cartridge is, but it looks like it would be swell. My guess is that they were loaded up in the '60s but not sure. The brass is 2-9/16"

.

quote:

275 H&H killed by the 7mm Rem mag and the 275 bullet, oddball !

I don't think it does! It uses .284" just like a 7mm Mauser or 7mm-08. It is the 280 Ross that uses the bastard size.

.

It works well with both .284" and .288" diameter bullets. The groove diameter was .004" larger than the "American" 7m/m, but the bore diameter was not that much bigger on the two Holland's built .275 H&Hs I owned...the bores were more like only .001" bigger, but the grooves were markedly deeper than the standard U.S. 7m/m.

Other rifles may be different, but that's the way the two I had were. Standardization in barrels wasn't fantastically great in those days, so I suppose one might run across almost anything.