.378” minus .375” = .003”...or better known as a human hair

R

Roamin_Wade

Moderator
As an ammunition collector I was looking at all the Weatherby rounds and came across the fact that they make/made a .375 and a .378 round. I think the .375 is the new and the .378 is the old but I may be wrong. It may be the other way around. Does anyone know why they made one proprietary round so close to another proprietary round?
 
.378 Weatherby still uses .375" diameter bullets.
They just wanted a number that made it sound bigger, badder, betterer, and most awesomest.


.327 Federal is of similar naming convention, with added fluff.
.312" diameter bullets, or .32 caliber; with the seven referencing .357 Mag.
 
The .375 dates from 1944, is based on the .375 H&H and runs $122.99 per 20 from Midway. The .378 is inspired by the .416 Rigby, but not based on it. It dates from 1953 and runs $139.99 per 20.
It is alleged that Roy Weatherby invented the .378 because his .375 wasn't any better than the .375 H&H. As with anything with 'Weatherby' in its name it primarily just costs more. A box of .375 H&H ammo starts at about $60 at Midway. Far greater selection too.
 
The difference between the 375 Weatherby and the 378 Weatherby is massive, even to inexperienced observers.

* The 375 Weatherby is an improved 375 H&H, so .530" case rim, belted, with a case head diameter of .521", shoulder diameter of .440", and a case length of 2.85", launching a .375" 300 gr bullet at 2,700 fps (a 200 fps gain over the H&H).

* The 378 Weatherby is a necked down 460 Weatherby, so the rim diameter is .580", the case head is .582", the shoulder is .560", and the case length is 2.913". It launches a .375" 300 gr bullet at 3,000 fps (about 20% faster than a 375 H&H).

Years ago, I got the chance to fire a 378 Weatherby. I owned a 375 H&H at the time, so I thought no big deal. All I can say is WOW. If you ever wanted a 375 H&H to look puny, hold it your hand next to a 378 Weatherby. The 378 Weatherby is 20% bigger in diameter than the 375. If you ever get the chance to shoot one, there is no similarity.
 
This sort of thing isn't uncommon. When S&W came out with the 38 Special it actually fired a 35 caliber bullet. But they chose to measure the case diameter instead of bullet diameter to give buyers the appearance they were buying a larger caliber gun. The 44 mag actually fires a .429 bullet. The 257 Rigby and 7X57 are the same identical cartridge, the British just called it 257 Rigby while everyone else called it 7X57.

There are no rules for naming cartridges. The inventor can call it anything they want.
 
There are no rules for naming cartridges. The inventor can call it anything they want.
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Pretty much...

however, there are some more or less standard conventions that are usually followed. One is that the number in the cartridge name have some relationship to the caliber of the bore, but need not be the exact diameter or the bullet used.

In the early days of pistol rounds, (revolvers are pistols, too..;)) the .38s were actually .38 caliber bullets. Rounds were loaded with heel type bullets (like .22LR still is today) where the widest part of the bullet is the same diameter as the case, and there is a smaller diameter "heel" of the bullet inside the case. When this changed to inside lubricated bullets the widest part of the bullet was inside the case, and of course, in order to fit, a smaller diameter. With the lead bullets of the time, the smaller diameter of the "new" bullets didn't matter much, as the lead would upset in the bore and seal well enough for accuracy.

Over time, the actual bore diameter dimensions were reduced to match the bullets, but the original caliber names were kept. Which is why .38s are actually shooting .36 (.358"" diameter bullets.

Another convention is using bore diameter measurements (not bullet diameter) in the cartridge name. All the common .300s and .308s use the same diameter bullets (.308) just .300s are named for the land to land bore diameter, while .308 is the measurement groove to groove.

As to something like the .275 Rigby, its the English measurement of 7mm (.284") minus groove diameter, changed from the actual .276" measurement for market appeal (.275 was thought to be more appealing to the buying public than .276)

Another convention is using a name that includes the parent case, such as 7mm-08 (a 7mm bullet in a necked down .308Win case) or .22-250 (a .22 made from the .250 Savage case).

However, on the other side of the pond, they do it just the opposite way, putting the parent case name first. .577/450 Martini, .450/400 Jefferries, etc.

There are other "rules" that are generally followed, and then there are a host of exceptions.
 
The 257 Rigby and 7X57 are the same identical cartridge, the British just called it 257 Rigby while everyone else called it 7X57.
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Ummmm, no. That's .275 Rigby. That's a .275" bore, but groove diameter is .284"-.285".

A .50 BMG projectile starts out as .510" diameter, but is .0500 by the end of the barrel
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Ohboy. Again, no. The GROOVE diameter (therefore the bullet diameter) is .510" The BORE diameter is .500", hence 50 caliber.
 
Well there’s a lot of good info in all of your responses. I got into this group because I’m tired of Facebook but I wish I could “like” the posts I’ve seen in here like one can in FB.
 
Maybe the diameter of the lands of a .50 BMG is 0.50"; I dunno.

But groove diameter = bore diameter and is 0.511"--which is the bullet diameter.

But enough OT for one day, okay? :) Back to .375/.378.
 
I've had 4, 375H&Hs and one 378 Whby. I bought 378 about 5th hand. Everyone
thought they wanted it until they owned it. I know rifle didn't have 100rds total
when I got rid of it. The recoil didn't run me of it was accuracy. I bought dies and
fooled with it all summer. It would not touch my old Sako 375H&H for accuracy.
The 700 Rem outshot it. I had a post 64 m70 that was about the same as far
as accuracy, but Whby was a slick and pretty rifle. I've never shot a 375 Ruger
only #1 in 375H&H and I have a couple #3s in 375 Win. Only because I need
them for Ohio deer season.
 
I have a 375 Weatherby. It is not quite a 378 Wby but if you use the old load data, its definitely a huge improvement over the H&H.
 
The first use of a .338" bullet I know of is the .33 WCF, ca 1902 in Winchester 1886 lever action.

I think the .378 Wby predates the .460.
Case is pretty much a belted .416 Rigby. Before the resurgence, the only source of Boxer .416 was by turning the belt off Weatherby brass.
 
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