Independent Study: LRH calibres - 7mm WSM vs 300 RUM vs 338 LM

[Haagen Dazs]

Cool, thanks for the input. So how would the 338 Norma Mag compare to the 7mm WSM and the 338 Lapua by those calculations assuming the same 3/4 MoA at 1000 yards? Do you go by powder capacity or H2O capacity?

 

[Bart B]

Haagen, I go with powder; ammunition uses powder, not water.

Calculate the area in square millimeters of any bore and that's the charge weight in grains when producing a max safe load that's at bore capacity.....by my formula. At top accuracy levels, it gets about 3000 rounds of barrel life

Double that amount of powder for the same caliber and barrel life drops by 75% for the same accuracy level.

So, a .338 caliber has a bore capacity of about 59 grains. A .338 Win. Mag. (I don't think there's a .338 Norma Mag) burns about 64 grains of powder shooting 300 grain bullets. It'll have about 2300 to 2500 rounds of 3/4 MOA accuracy at 1000 yards......providing the loads and the rifle plus its sights and the shooter's ability can do that.

 

[bigngreen]

Here's some info on the 338 Norma from guys who shoot it and know what it is, http://www.longrangehunting.com/forums/f93/338-norma-review-ward-w-brien-46637/

 

[Haagen Dazs]

Here's some info on the 338 Norma from guys who shoot it and know what it is, http://www.longrangehunting.com/forums/f93/338-norma-review-ward-w-brien-46637/

Already read through the article and the discussion. That's waht put me on this track.



As for bore life, if the 338 NM can get 2000 rounds, thats about double what a hot 7mm WSM should get, which is about 1000 from what I've read. Hard to say, but thanks for the different approch!


338 NM 82 gn = 1.42 gn/sq mm
7mm WSM 60 gn = 1.47 gn/sq mm