375 Weatherby Mag loads

eezridr · January 4, 2009, 07:59 PM

Anybody have any good 375 Weatherby Mag loads out there that approximate factory ballistics (300 gr. bullet at 2800 fps ; Nosler Partition). I have chronographed the factory offering and it is spot on in my custom stainless Win Mod 70 (24" barrel).
Getting a little tierd of $90.00 + for a box of shells and load data is scarce.
If you have a good 300 gr Swift or triple shock that woud be great.

EZ

**Unclenick** · January 4, 2009, 09:54 PM

Did you check the load data on Nosler's site?

eezridr · January 5, 2009, 11:51 AM

Nosler actually offered this load in their custom ammo offering for a while but have discontinued it.
There is nothing in their most recent reloading manual and I have actually e-mailed them for any info they could provide regarding the loading of their ammo. They responded however they stated they had no info available. I can only suspect Nosler outsourced the manufacturing of their custom line of ammo.
My rifle is a 375 weatherby; not a 378. The 375 Weatherby was introduced for a few years prior to the development of the 378. Weatherby still offers ammo for the 375 via Norma

Scorch · January 5, 2009, 12:07 PM

Don't know if you are looking, but I have several boxes of Weatherby factory brass for the 375 Weatherby I am trying to sell. Interested?

As far as a load
375 Weatherby, 300 gr spitzer, IMR4350, 87.7 gr

Shoney · January 5, 2009, 04:49 PM

I have a freind that is a well respected gunsmith. He is approved to do certain types of Wthby Factory Warantee Work.

In discussions of handloading, he said that none of the people he dealt with could get nearly the same velocities as those produced by factory ammo. They tried and found damage to their weapons from over pressure loading.

He discussed this with techs at Wthby, who said that the powder is usually a blend of two powders not commercially available. In addition the powder was charged by specialized long drop tube technology, which pack the powders tightly into the cases. Stuffing a bullet into a case full of powder will not give you nearly as much powder capacity as the factory can pack.

eezridr · January 5, 2009, 04:59 PM

Shoney;

That is interesting. I have been able to exceed Weatherby factory published ballistics in their 257 and 270 offerings very easy with no high pressure indications (chrono'd). I can almost meet ballistic on the 340 but it would appear to get to the 375 data is a challenge.
The larger caliber Nosler partitions; 338 and above are far tougher than the smaller calibers. I believe the shank wall thicknesses are far heavier. It is a good projectile that should fill 99% on my softpoint requirements. Problem is there is no factory solid offering. I guess I will just load to 2700 FPS which should be very satisfactory.

EZ

Shoney · January 5, 2009, 06:00 PM

eezridr

Have you calibrated your chrono?

How far off the barrel are you puting the chrono?

The reason I ask is because I used to think my velocities were getting much higher than book data, yet showing no pressure signs at max loads. Since I didn't understand what was going on, I called the chrono factory.

The chrono company asked what elevation I was shooting at, because at higher elevations the air is less dense and higher velocities could be expected. Since I wasn't at high elevation, they told me to calibrate my chrono using high quality .22 LR, where the expected velocity is on the box (Federal 900B for example).

The quality ammo was to be fired out of a 24" bolt action or lever action .22, and should achieve the stated velocity within 50 fps or closely thereabout. The .22's usually vary less from the stated velocity than most commercial and handloaded centerfire cartridges. I was also told that the escaping gasses with unburned powder and residue particles of the cenerfire ammo crossing the chrono can give false high readings.

Sure enough, my chrono was off.

**Unclenick** · January 5, 2009, 06:54 PM

Sorry I misread .375 and .378 earlier. But Shoney is correct. They had some proprietary loading system akin to the Hornady Light Magnum rounds. A little over 2700 fps with Ramshot Big Game or Reloader 17 is maximum according to the QuickLOAD powder table generator.

Shoney,

I hadn't heard of rim fire calibration before. I wound up building an old fashioned break-wire ballistic chronometer I could rig to the sky screens with tape. It's precise, where the .22's are ±50 fps, as you say, but I've always wanted a simple method to pass along to others that would get them close. Thanks for putting that up.

eezridr · January 5, 2009, 08:21 PM

Shoney,

I place my Ohler 35 about 10'-12' from the muzzle. I have reloaded probably 35 years. My velocities that beat factory ammo are above listed max. charges. I have experimented going up .25-.5 grains over the yerars in many calibers. I will have to say that the Nosler and Barnes published data on the 270 weatherby (Mine is a weatherby super big game master rifle) matches my chronoed data right on the dot. Typically the published data shoots faster than my rifles. That is probably due to tighter chambers and better cut rifling in test barrels.
One of my favorite loads is 61.5 gr of RL-22 and 130 gr bullet in a 270 winchester.
This is quite a bit over max listing however I have 4 270 rifles and none show any pressure indications with this loading. It shoots a bit over 3200 fps with a low std dev. and great accuracy.

My 375 weatherby was initially a Stainless Mod 70 in 375 H&H. I had the barrel cut recrowned when I had it rechambered. Had the action squared and polished. Changed out the cast extractor to a machined unit (as on all my mod 70's). Trigger set at 2 lbs, added a McMillan safari drop box type fiberglass stock and added Sunny hill stainless bottom metal.
NECG custom front barrel band sight and a Talley bases modified by Brockman that includes a spring loaded rear peep sight.
After all this investment; The gun will shoot into 1" or less at 100 yards. I got lucky!
This gun will shoot the 300 gr pills at 2800 FPS and change according the the Ohler 35. I
To answer your question; I have not had the chrono checked but it typically chronos low relative to published relaoding data.

EZ

Shoney · January 5, 2009, 09:09 PM

Unclenick
You are welcome, but I can't take much credit here. I just did as I was told, I'm the PHD in the equation (Press Here Dummy that is).

eezridr
Quality weapon, quality glass, quality mounts!!!!!!!!!!!!!!!!!!!

I have to admit that it has been well over 20 years since I worked with any Wthby loads. It's funny how kids alter your lifestyle. I went from a tack driver for sport to a taxi driver for kids sports.

I suppose it is very probable that the secret proprietary powders made it onto the open market, and thats good

.

January 4, 2009, 07:59 PM	#1
eezridr Junior Member Join Date: January 1, 2009 Posts: 9	375 Weatherby Mag loads Anybody have any good 375 Weatherby Mag loads out there that approximate factory ballistics (300 gr. bullet at 2800 fps ; Nosler Partition). I have chronographed the factory offering and it is spot on in my custom stainless Win Mod 70 (24" barrel). Getting a little tierd of $90.00 + for a box of shells and load data is scarce. If you have a good 300 gr Swift or triple shock that woud be great. EZ

January 4, 2009, 09:54 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	Did you check the load data on Nosler's site? __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 5, 2009, 12:07 PM	#4
Scorch Senior Member Join Date: February 13, 2006 Location: Washington state Posts: 15,248	Don't know if you are looking, but I have several boxes of Weatherby factory brass for the 375 Weatherby I am trying to sell. Interested? As far as a load 375 Weatherby, 300 gr spitzer, IMR4350, 87.7 gr __________________ Never try to educate someone who resists knowledge at all costs. But what do I know? Summit Arms Services

January 5, 2009, 04:49 PM	#5
Shoney Senior Member Join Date: February 21, 2002 Location: Transplanted from Montana Posts: 2,311	I have a freind that is a well respected gunsmith. He is approved to do certain types of Wthby Factory Warantee Work. In discussions of handloading, he said that none of the people he dealt with could get nearly the same velocities as those produced by factory ammo. They tried and found damage to their weapons from over pressure loading. He discussed this with techs at Wthby, who said that the powder is usually a blend of two powders not commercially available. In addition the powder was charged by specialized long drop tube technology, which pack the powders tightly into the cases. Stuffing a bullet into a case full of powder will not give you nearly as much powder capacity as the factory can pack. __________________ I pledge allegiance to the Flag - - -, and to the Republic for which it stands….Our Forefathers were brilliant for giving us a Republic, not a democracy! Do you know the difference??? and WHY?http://www.wallbuilders.com/LIBissue...les.asp?id=111

January 5, 2009, 06:00 PM	#7
Shoney Senior Member Join Date: February 21, 2002 Location: Transplanted from Montana Posts: 2,311	eezridr Have you calibrated your chrono? How far off the barrel are you puting the chrono? The reason I ask is because I used to think my velocities were getting much higher than book data, yet showing no pressure signs at max loads. Since I didn't understand what was going on, I called the chrono factory. The chrono company asked what elevation I was shooting at, because at higher elevations the air is less dense and higher velocities could be expected. Since I wasn't at high elevation, they told me to calibrate my chrono using high quality .22 LR, where the expected velocity is on the box (Federal 900B for example). The quality ammo was to be fired out of a 24" bolt action or lever action .22, and should achieve the stated velocity within 50 fps or closely thereabout. The .22's usually vary less from the stated velocity than most commercial and handloaded centerfire cartridges. I was also told that the escaping gasses with unburned powder and residue particles of the cenerfire ammo crossing the chrono can give false high readings. Sure enough, my chrono was off. __________________ I pledge allegiance to the Flag - - -, and to the Republic for which it stands….Our Forefathers were brilliant for giving us a Republic, not a democracy! Do you know the difference??? and WHY?http://www.wallbuilders.com/LIBissue...les.asp?id=111

January 5, 2009, 11:51 AM	#3
eezridr Junior Member Join Date: January 1, 2009 Posts: 9	Nosler actually offered this load in their custom ammo offering for a while but have discontinued it. There is nothing in their most recent reloading manual and I have actually e-mailed them for any info they could provide regarding the loading of their ammo. They responded however they stated they had no info available. I can only suspect Nosler outsourced the manufacturing of their custom line of ammo. My rifle is a 375 weatherby; not a 378. The 375 Weatherby was introduced for a few years prior to the development of the 378. Weatherby still offers ammo for the 375 via Norma

January 5, 2009, 04:59 PM	#6
eezridr Junior Member Join Date: January 1, 2009 Posts: 9	Shoney; That is interesting. I have been able to exceed Weatherby factory published ballistics in their 257 and 270 offerings very easy with no high pressure indications (chrono'd). I can almost meet ballistic on the 340 but it would appear to get to the 375 data is a challenge. The larger caliber Nosler partitions; 338 and above are far tougher than the smaller calibers. I believe the shank wall thicknesses are far heavier. It is a good projectile that should fill 99% on my softpoint requirements. Problem is there is no factory solid offering. I guess I will just load to 2700 FPS which should be very satisfactory. EZ

January 5, 2009, 06:54 PM	#8
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	Sorry I misread .375 and .378 earlier. But Shoney is correct. They had some proprietary loading system akin to the Hornady Light Magnum rounds. A little over 2700 fps with Ramshot Big Game or Reloader 17 is maximum according to the QuickLOAD powder table generator. Shoney, I hadn't heard of rim fire calibration before. I wound up building an old fashioned break-wire ballistic chronometer I could rig to the sky screens with tape. It's precise, where the .22's are ±50 fps, as you say, but I've always wanted a simple method to pass along to others that would get them close. Thanks for putting that up. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 5, 2009, 09:09 PM	#10
Shoney Senior Member Join Date: February 21, 2002 Location: Transplanted from Montana Posts: 2,311	Unclenick You are welcome, but I can't take much credit here. I just did as I was told, I'm the PHD in the equation (Press Here Dummy that is). eezridr Quality weapon, quality glass, quality mounts!!!!!!!!!!!!!!!!!!! I have to admit that it has been well over 20 years since I worked with any Wthby loads. It's funny how kids alter your lifestyle. I went from a tack driver for sport to a taxi driver for kids sports. I suppose it is very probable that the secret proprietary powders made it onto the open market, and thats good. __________________ I pledge allegiance to the Flag - - -, and to the Republic for which it stands….Our Forefathers were brilliant for giving us a Republic, not a democracy! Do you know the difference??? and WHY?http://www.wallbuilders.com/LIBissue...les.asp?id=111 Last edited by Shoney; January 5, 2009 at 09:15 PM.