Home Forums Hunting & Shooting Express Rifles and Big Bores Only 378Wby original factory ballistics, anyone achieve it?

Some old data for the 378 factory rounds had two loads, and I am just going back to the early 90's here, so maybe there were other iterations. A 300 grain at around 2900fps for about 5700fttlbs and the 270 grains at remarkable 3180fps for about 6064ftlbs....it was a bit of a difference in power and I always wondered if the second figure had some blue sky figured into by Roy.

Karl,

I have had plenty of 378s. They are 3150 f/s with 270 grains and a bit over 3000 f/s with 300 grains. That with Re22, 2213 and the old original 4831.

For Americans. 2213 is the earlier version of what Hodgdon sell as H4831 SC.

The 378 in 26" barrel is virtually identical in velocity to the 300 Winchester in 26" barrel with bullets of the same sectional density, a 270 grain is same as 182 grain 30 and the 300 grain is same as 202 grain 30 so the 378 is just a tad faster than the 300 Winchester.

I have chronographed over a large spread of years the 270 grain factory load which has always looked like the 270 grain Hornady and velocities have ranged from a low of 3080-3100 to a high of 3150-3180. I have never chronographed or even shot the 300 grain factory load.

Here is data from AR's reloading pages and it's Mitch Carter's loads. Mitch was the king of shooting the 577 T Rex.

http://www.accuratereloading.com/378wby.html

I did in the late 80's on through the mid 90's with IMR-7828 under 270gr Hornadys and 300gr Partitions.

3200 fps with the 270's
2950 with the 300's

Even had a 'deer load' with IMR-4350 under 235gr Speers at 3600 fps, yes, the very definition of "train wreck" when it landed.

Brass was good for 3-4 firings before pockets got loose, it was a hell of a cartridge and rifle, bought it in 1987 a Carter Country Sports in Houston.

Forgot one, 250gr Sierra BTSP's ran 3500 fps with IMR-4350, too be that young, single and slap full drunk on piss and vinegar, lord help me!

I've always been in awe of the 378 Wby. Its ballistics are pretty incredible, with varmint rifle-like trajectories but with a 270gr bullet. I had Charlie Sisk build me a custom in 378 Wby. If I were ever interested in shooting Moose or Elk at 500-750 yards, this would be my tool.

158XTP,

After I dragged that 1984-model Mk V Deluxe 460 WBY from Missouri to Alaska to Florida and back to Alaska,
I traded it in on a BRNO ZKK 602 .375 H&H that had a 22" barrel.
The BRNO had a beat-up factory stock and an unfinished walnut custom stock that caught my eye.
Some old sourdough had given up on getting it finished and left it at Boondock Sporting Goods.
Even swap to the returning sucker, er, sourdough.

I returned to KY and had a TN gunsmith work on it in 1998.
I had that 22" .375 H&H BRNO rechambered to 378 WBY and had the custom walnut stock crossbolted, pillar bedded, checkered and finished,
and a Pachmayr Triple-X Magnum (1.5") was installed.
I had two boxes of the old Tiger-on-the-box factory ammo.
I fired 6 shots, 3 from each box and chronographed at 5 yards, 85 degrees F.
Factory bullet was the Hornady 300-gr FMJRN, BC = 0.275.
Velocities ranged from 2833 fps to 2886 fps.
Average = 2851 fps.
Add 17 fps to correct to MV = 2868 fps
Add 120 fps for a reasonable correction to 26" barrel length MV = 2988 fps

But the primers were cratered and the bolt was sticky, accuracy ho hum, but muzzle blast was, shall we say noticeable in the 22" barrel ?
Conclusion: Factory ammo was loaded too hot for my rifle, but might be doing the claimed 3000 fps in some rifles ?
I pulled the bullets and used the brass for handloads.

Times changed and factory ballistics backed down to closer to 2900 fps with 300-grainer.

I later settled for a CZ 550 Magnum .375 H&H re-chambered to .378 Wby, with 25" factory barrel.
Using IMR-7828, 111.0 grains, with any 300-gr bullet,
5 shots of 300-gr Swift A-Frame averaged 2878 fps, and first 3 of those went into just under 1" at 100 yards, before I started flinching.
No signs of pressure.
Add an inch of barrel and a BC correction from 5 yards to muzzle, and that load should be a bit over 2900 fps MV in a 26",
just about spot-on for 2900 fps in my 25" CZ barrel.
That is the extent of my load development for the .378 WBY.

Mitch Carter had a favorite load in a 26" .378 Weatherby.
I jotted it down when I studied 577 Tyrannosaur torque control technique with him at Long Island, NY in 2001:

300-grain Barnes X-Bullet (first generation)
Alliant RL-25: 116.0 grains
Claimed velocity: 3024 fps
Accuracy < 1" at 100 yards

I also have a Weatherby MK V barrel chambered at the Weatherby Factory and then some sourdough cut it off to 22" and installed barrel sights.
The then current holder of the barrel was happy to throw it in as boot on the trade when I acquired his .30/.378 WBY MK V which also had its original factory barrel.
I do not know where he got that stubby .378 WBY barrel.
He would not admit to having it bobbed himself.
I am still waiting for an excuse to try factory .378 WBY ammo in that one too.

Ron

Elephant on the 378 and 460. People pay good money for empty packets. Weatherby should bring those packets with the different animal/calibre boxes and also the Weatherby catalogues of old.

Mike.
Right you are. I have only two of those old elephant paper box empties left from .378 WBY.
I must have sometimers-ed the tiger, maybe that was from the old .340 WBY ?
I fear I might have thrown out the old Weatherby catalogs too.
Shame on me !

I have chronographed records for some of Mikes' old loads in a slim #3 barreled .378.

220gn Hornady 114gn IMR 4350 = 3380fps and 5582 FPE
235gn Speer 112gn IMR 4350 = 3336fps
270gn Hornady 117gn AR 2213 (H 4831) = 3178fps and 6057 FPE
" 117gn H 4831 (Surplus) = 2998fps
300gn Hornady RN 102gn AR 2213 (H 4831) = 2650fps
300gn Swift A-Frame 111gn Rel 22 = 2928fps
113gn Rel 22 = 3006fps


(I typed in spaces to align the loads but the site scrambles the data.)

John,

They were called a Modified Number 2. If anyone ever needs to know the minimum possible muzzle diameter for a 375 bore then measure one of there !!!!

Number 3 is the Made in USA 378s from about 1995, the 416 and the Accumark. The make a 378 a much better rifle

John, that old surplus 4831, wasn't that some you had in sealed tis and was in sealed tins and we thought velocities were about 100 f/s down on what we tried it in?

For auld lang syne,
I bought these two boxes of 378 WBY ammo at a gunshow just before covid shut everything down:



Only paid $80 US per box. Bullet is 300-gr RNSP, loaded in Sweden by Norma.
Doesn't look like Hornady bullet this time.

Norma manual shows a load for Woodleigh 300-gr RNSN:
Norma MRP 110.2 gr (maximum) >>> 2933 fps MV in 26" barrel.
and for the Hornady 270-gr SP:
Norma MRP 116.2 gr (maximum) >>> 3130 fps MV in 26" barrel.

Here is the more recent .416 WBY factory load for about $200 US per box:



I have 6 boxes of factory ammo (300-gr Nosler Partition) and 4 boxes of unprimed brass for the .375 WBY
to supplement the ones I formed from Hornady basic cylindrical and W-W .375 H&H brass.
100 rounds of the factory ammo are hermetically sealed in clear packaging tape like the one box on top below,
for the coming apocalypse:



I wish I still had all those old elephant boxes for the 460 WBY.

Mike,
I had 3 containers of this powder, 2 were tin containers, one sealed and the 3rd was a tall plastic bottle with an old fashioned typewriter labeling on it. That one was also sealed and I gave it away when I came over here. Of all the cartridges I tried this powder in, it responded most favorably in the.340 Weatherby and I actually brought cartridges here with that rifle. (with ATF Approval)

I recall the barrel differences except that original .378 as I had both #3 with the .416 Weatherby and #4 with the .460. This was all confused by the non standardization in the industry as I still have a Tobler #5 profile and they are not similar. Bill Nioa had a custom #4 profile in .378 that I tried to get off him but someone beat me to it. Did you get it?

Great history and information gents. So the ballistics were certainly achievable. I always found despite being smaller there was something obscenely impressive about the 378wby even alongside its bigger brothers. I think Roy adding a couple numbers extra to the name helped too(460 for 458 and 378 for 375, 340 for 338 etc), he knew how to market a calibre name. Interestingly when the 416 came out which was later, he stuck with .416...

Ron, that silver packet with the basic writing must be at least early/mid 90's? Thats the ammo boxes I ordered with my 460.

The 378 with Partitions or XXX is quite impressive for those who can handle it.
Charlie

My 378 easily spits 300 grain barnes at 3050fps, chrony not guessed. I hit a white tail in left shoulder, it seemed to have flown a little bit. When l went to roll it over the front leg almost fell off. There was a football size hole in it. Amazingly the bullet was still inside, it had traveled the full length of the deer and found near the tail in the spine. I dont shoot deer anymore. The 378 has 6000 foot pounds at the muzzle. Hits with 3000 ft/lbs at 500 yds and only drops 36 inches using the 270 grain. Shot a moose, the bullet went through a 12 inch pine tree and went right through both lungs, the bullet was found under the hide. The lungs were full of bark and wood splinters.
The bullet had skinned the animal on the backside about a 1.5 ft circle where the bullet hit the hide a bounced back like a trampoline. My friend who witnessed the shot said a huge dust storm occurred. I never saw that bit because l working with the recoil at the time.

l forgot to mention not much was left of the 235 grain bullet, found same with the 300 grain bt hornady used on moose, the bullets almost disentegrated. When you looked at the tree from exit side, it looked like a shotgun blast had exited the tree. The barnes are the best to hold together of all the various bullets l have used through the years. 460 is now illegal in Canada, and 50 cal. These 2 animals shot within 60 yd.