.338-378 vs 338 lapua

[585 Nyati]

If both calibers were made in the perfect weapon system with an expert shooter, and in the same conditions, which would perform better past 1000 yards in terms of accuracy, power, and penetration?


I know the .338-378 is a little faster, but I don't know enough about the rounds to say that gives it an advantage or not

 

[HOGWILD]

The .338-378 Weatherby cartridge uses the .378 Weatherby case, necked down to take a .338 bullet. That means it is a whopping big cartridge case. The .338-378 Weatherby case holds 137 grains of water compared to the .338 Lapua, which holds 114 grains of water. That’s about a 20 percent increase in case capacity. More capacity means more propellant and more propellant means higher muzzle velocity. While the laws of diminishing returns start to apply with this big case, it still can push the same bullet substantially faster than the Lapua. That means the bullet gets to the target faster, retains more energy and has a flatter trajectory curve.

I have not stretched mine out to far yet but it will not be long once NM weather starts to cooperate a little! Scope gives me 66 MOA but a tad less once I get a zero!

 

[Diablo]

Nice Accumark.

I worked with the .338-378 back during the '90s, when there was an ample supply of H870.

The H870 made it easy to load, since it usually took a case full, (depending on the bullet weight).

My rifle did not have a muzzle break (those are for sissies).

Today, I might still opt for the 338-378 (nostalgia) but would use a full fill stock, thread the barrel, and use a can with it.

(and maybe hire a gun-bearer to tote it for me in the mountains)

 

[HOGWILD]

This rifle has a 2.8 Lb Timney on it and is a tack driver so far! Only reason I use the break is I am on blood thinners but it has a thread protector for it! So far i have only fed it 225 Gr TSX's coming out at 3180 and it is fun to shoot! They make a TRR version that is more of a tactical look to it!

 

[DAVETOOLEY]

Speed without accuracy doesn't work at distance. From many years of smithing 1K comp guns you can't get the same level of accuracy from the larger case. For pure accuracy the 338 Norma wins with the Lapua second.

 

[585 Nyati]

Speed without accuracy doesn't work at distance. From many years of smithing 1K comp guns you can't get the same level of accuracy from the larger case. For pure accuracy the 338 Norma wins with the Lapua second.

Does this mean the Lapua beats the 338-378 weatherby at 1000+?

 

[DAVETOOLEY]

Does this mean the Lapua beats the 338-378 weatherby at 1000+?

You have your own definition of "Beats" and I have mine. You have to determine that yourself.

 

[HOGWILD]

Mr Tooley you would know way more than I and I respect your knowledge, and expertise as I do not shoot comp with this rifle just an occasional range trip and wanta try longer than 1000 yds eventually! I think this round would do nice out past 1000 but what would you say? Is stability just an issue ? What cause's the larger cartridge it's issues? At distance!

 

[DAVETOOLEY]

Everything is a compromise. Remember every bullet is unique and has it's own unique set of flight characteristics. As the speed increases the aerodynamic inconsistencies of the bullet are affected more resulting in a loss of pure accuracy. If you reduce speed you increase drop and wind drift. So it's back to what is your definition of accuracy. Grouping ability or reduction in wind drift because most of the time you can't have extremes of either. Personally I want just enough speed and BC to get the job done then I want accuracy. As to case capacity, I like balance between the caliber and powder capacity. Usually works out better in the long run.
Stability- Once a properly designed long range bullet leaves the muzzle and is stable it will remain stable.

 

[Supersubes]

Like Dave said, of your two choices, the Lapua is the better of the two in accuracy. From your post, I'm not sure what your goal is. You should figure out a realistic goal, and taylor the gear to match. I built a .338 years ago using all top of the line components. I had planned to shoot it to it's max effective range, but never really did any of that. A the distances I did shoo very often, 1300 and under(steel targets), I was much more accurate with my .260. I sold the .338. I'll build another some day, and it will probably be a .338 Norma mag.