Igm270,
I think we are majoring in minors here. There is little, if any, difference in practcial performance between all the std (30-06 size) .30 cal magnums. But as "factory" initiatives the .308 Norma Mag was the first (though not chambered in by US factory, it gained factory, non-wildcat, status as the factory offered cases, loading data, ammo and reamers) and ever since that the US makers have, for their own purely commercial reasons and advantage, been playing catch up. The .308 Norma ignited the post war love affair US, and therefore global, shooters commenced with the high performance belted factory magnums, that Roy Weatherby experimented with as a wildcatter in the mid 1940s. Although, according to the late, great Jack O'Connor in his excellent book "The Hunting Rifle" (Winchester Press 1970) the .30 magnum trend owed its real genesis to the 30 Newton in the US and the .300 H&H (although the latter needed a magnum mauser action and is rightly grandfather of the .30 ultra magnums) developed before WW1. But the .308 Norma Mag rightly enjoys the reputation as the grandfather of what we could call today the factory produced modern (post war) .30 cal standard belted magnums, that is a matter of history and no playing with rifle building ("long throating", et al) or loading technique can change.
The .300 Win Mag, as I have said in a previous post, a excellent cartridge in itself, owes its shape (shoulder position) to an attempt to differentiate it from the .308 NM, with which it was primarily designed to compete, not to any concept of producing higher velocity (all other things being equal) or ballistics advantage. This is borne out by the various loading tables. A quick look at the 180gar and heavier bullets loadings (the forte of the .30 cal magnums) for both cartridges you'll see that for all prpractcialurposes they get the same performance. There may be slight differences that may be ignored and for prpractcialurposes explained as normal difference between rifles.
Now to get away from the hypotheticals. As I said in a previous post in this thread, my .308 NM (built on a standard FN M98 [non-magnum] action) albeit, at the time, an expensive classic custom hunting rifle with no long throating, but standard factory specification chamber and freebore with a 24" (not 26") Douglas premium barrel shoots 180 gar Hornady SPBT (stock# 3072) cchronographed(with a CED Millennium chronograph) at the SSAA rifle range in Brisbane, Australia at over 3,100 fps and up to 3,153 fps. These are good shooting loads too as the following target (3 shots @ 100 yards, 0.709"), shot while developing these loads, verifies. Also I have never encounter any difficulty with cartridge/magazine fit with normal seating of bullets. As you'll see from the photo of my rifle in a previous post, it is no specialized long range (long throated, 28" barreled) rig. It is just a normal hunting rifle designed to carried all day in the field.
I have yet to spend serious time developing loads for the 200 gr bullets (I have a quantity of Nosler partitions ready for a Northern Territory buffalo hunt) but don't anticipate any difficulty with these.
I would venture to suggest (though I have not actually measured it) that the slightly extra powder capacity of the 300WM (produced with a case designed not to be capable of being chambered in .308 NM rather than to produce extra performance) with like bullets, and all other things being equal, would be almost entirely lost to the space required in seating bullets to fit a standard short magnum magazined hunting rifle.
Remember, the original post (the one the started this thread and the subject matter for posts) was "What do you guys think of the 308 norma mag?
Opinions wanted." There is nothing wrong, in fact several things right, with this wonderful classic cartridge that can rightly claim to be the grandfather of all modern factory standard .30 cal magnum and with which all will be compared.
Having said that, if I were wanting a factory hunting rifle today there would be nothing wrong with purchasing one of the excellent .300 Win Mags available off the shelf, it is an excellent performer. However, I choose instead to have something a little different from the crowd and since I am a fan of classic calibres a have a custom built classic .308 Norma Magnum which is a modern a rifle and calibre as one could ask for today.
Cheers,
magnum308
