Who is currently loading for this caliber? I have a custom Brno 602 and looking for some suggestions for loads to start with.

Not a starting load but...

86 grains H-4350 seems to be the magic load in mine under a 300 grain TSX. 85 grains under the Barnes Banded Solid brings the groups together.

Practice load is a Sierra over the same 86 grains of H4350. I haven't messed with the Swift A-Frame a whole lot but I suspect about 87 grains will tighten its groups up.

Weatherby brass and Federal large magnum rifle primers are used on everything.

Rifle is a stainless Model 70, PacNor three groove barrel, black Cerakoat and a McMillan SuperGrade stock.

I'm taking it to Tanzania Friday to see what we can find...

Again.........NOT a starting load (so start lower and work up to your rifle's satisfaction).

My pet load is a 250 gr. Sierra GK over 92 gr. H-414 in Weatherby brass with a Federal 210M primer. C.O.L. 3.595" and good for 3060 fps in my 26" A-Bolt S/S. Runs a bit under 1.5" @ 100 yds. for 5 shots.

Definitely not for elephant or buffalo. But will take the fight out of, pretty much, anything else in the world right quick.

Thanks guys. Currently I have some W760, IMR4350, Varget, RL15 and H380. For bullets, I have 300gr and 270gr Hornady and 260gr and 300gr Nosler AB. Would like to get some 300gr Sierra.

Haven't fired the rifle yet. I have lots of H&H brass and quite a few already fireformed. Got a set of Redding FL dies.

I read that H4350 is great. How much different is it compared to the IMR version?

Ian

I have tons of loads, but none using the powders listed. Treat H4350 as close to IMR 4350 but not the same. The problem I had with W760 was too much space left -- recoil set the bullets into the case. Slower powders allowed me to seat compressed loads at the cannelure (for crimping).

PM me for more, if you like. RIP's page at Reloading is extensive and he is the guru.

Barry

The .375 WBY might be a bit hard on the 300 grain Sierras.

If you can afford it, you might pop for some premium bullets.

H4350 is a trifle slower than IMR 4350. Check your ADI (or whatever their new name is). You will likely be MUCH happier with single base extruded powders. Those fill the case nicely.

The Norma brand 375 Weatherby cases are the same as 375 Weatherbys all shiny in their boxes of twenty.

Use regular full power H&H loads to fire form the WBY cases.

This is a dividing line where you might consider using cross bolts, and going to smaller, tougher scopes.

Redding dies work very well. Polish them on the inside, and use Imperial sizing wax.

If you can dredge up some Failsafe bullets for serious hunting, you will be walking in tall cotton.

If you have not already done so, bed your rifle with a Steel Bed type of product. You should not need an extra barrel mounted recoil lug.

All the best.

LD

quote:

Originally posted by lawndart:
If you can dredge up some Failsafe bullets for serious hunting, you will be walking in tall cotton.

I happen to have 3 boxes (150 total bullets) of 300 gr. FailSafes I would part with if you or anyone else is interested.

quote:

Originally posted by McCray:
Not a starting load but...

86 grains H-4350 seems to be the magic load in mine under a 300 grain TSX. 85 grains under the Barnes Banded Solid brings the groups together.

This is the same load I use with fire-formed Remington brass and either CCI or Federal (if I can get them) magnum primers. Delivers 2,800 fps with no pressure signs and is very accurate, a real improvement over the old H&H. You are going to really like the .375 Weatherby!

RIP on here has done a lot of loading for the .375 Wby, you may want to search through some of his old posts.

I am going to pick up some H4350 and try it with my 300gr AB. I want to try some 300gr Sierra also.

those loads using IMR powder aut to fly pretty
fast if you get one.

Ian, PM me I have tons of chrono'ed data for the 375 H&H Ackley Improved, which is identical to the 375 Weatherby. I'll be glad to share it with you. Regards, AIU

quote:

Originally posted by Cane Rat:

quote:

Originally posted by McCray:
Not a starting load but...

86 grains H-4350 seems to be the magic load in mine under a 300 grain TSX. 85 grains under the Barnes Banded Solid brings the groups together.

This is the same load I use with fire-formed Remington brass and either CCI or Federal (if I can get them) magnum primers. Delivers 2,800 fps with no pressure signs and is very accurate, a real improvement over the old H&H. You are going to really like the .375 Weatherby!

RIP on here has done a lot of loading for the .375 Wby, you may want to search through some of his old posts.

Thanks for the reference, Cane Rat.
My old page has some good info, but needs to be updated with H4350 data, for sure.

The actual load data table on that page shows up blank on my puter, until I right-click on the table and "select all" and copy it. Then if I paste it here, it comes through without the photos and in a format that is hard to read.
I will try to add to this copy below, from the page:

http://www.accuratereloading.com/375wby.html

Maybe some others puters can see the table without the rigmarole I have to go through ... Java problem on my puter ... ???
************************************************************************************************

################################################################################################

375 Weatherby

R. A. Berry




THE RIFLE:
Winchester M-70 Classic Stainless .375 H&H rechambered to .375 Weatherby using a Dave Manson reamer,
throated with 0.3700” parallel-sided freebore length, and .3756" freebore diameter, and 1-degree-7'-0" leade.
(The CIP spec reamer is close enough to identical in throat after converting millimeters to inches.
Yes, the .375 Wby is both CIP and SAAMI approved!!! )
Barrel length 24 inches.
Magazine box is 3.625” in length.
The scope and mounts: Leupold Vari-X III 2.5x-8x with Leupold QRW rings and bases, with square recoil stop on bottom of each ring.

RELOADING COMPONENTS:

Brass used for the old load data immediately below: Hornady basic sized to .375 Weatherby, trimmed to 2.850”, and necks annealed.
Properly headstamped brass from Norma is best, see below.

Primer: Federal GM215M

Bullets: 250 to 350 grains

Propellants:
Reloder 15
IMR-4350
H4831SC
Norma MRP

Average Temperature: 50 degrees F.



Chronographed 15 feet from muzzle.



Groups for 3 shots at 100 yards, center-to-center, rounded to nearest tenth of inch.


The Load Data:
[Powder Name
Bullet Weight and Make
Powder charge in grains
Velocity fps (15 feet from muzzle)
Group size in inches, 3-shots at 100 yards
COL/COAL (inches)]



#############################################
#############################################

RL-15:

#############################################
#############################################


250 gr Barnes X FB:
############################################
77.0 gr Reloader 15
2755 fps
1.3"
3.600"
############################################


260 gr Nosler Ballistic Tip:
############################################
77.0 gr RL-15
2762 fps
0.9"
3.600"
********************************************
78.0 gr RL-15
2818 fps
0.8"
3.600"
*********************************************
79.0 gr RL-15
2845 fps
0.9"
3.600"
#############################################


265 gr Groove MI:
#############################################
77.0 gr RL-15
2763 fps
0.5"
3.600"
*********************************************
78.0 gr RL-15
2782 fps
0.6"
3.600"
*********************************************
79.0 gr RL-15
2805 fps
1.5"
3.600"
Ejector marks – Do not use
##############################################



270 gr Bridger Brass FN:
##############################################
77.0 gr RL-15
2748 fps
0.6"
3.600"
**********************************************
78.0 gr RL-15
2779 fps
0.8"
3.600"
**********************************************
79.0 gr RL-15
2826 fps
0.9"
3.600"
##############################################


270 gr Hornady SP:
##############################################
77.0 gr RL-15
2708 fps
0.7"
3.600"
##############################################


300 gr Hornady Steel FMJ (ye olde style):
##############################################
76.0 gr RL-15
2607 fps
1.6"
3.585"
##############################################


300 Bridger Brass FN:
##############################################
76.0 gr RL-15
2611 fps
0.9"
3.604"
##############################################


300 gr Bridger Copper FN:
##############################################
77.0 gr RL-15
2627 fps
0.8"
3.606"
##############################################


300 gr Bridger Copy of Walterhog:
##############################################
77.0 gr RL-15
2669 fps
0.5"
3.720"
**********************************************
78.0 gr RL-15
2717 fps
0.138": This is the smallest 3-shot rifle group at 100 yards that I have ever fired with a big game hunting rifle!!!
3.720" COL
Ejector marks – Do not use
##############################################


350 gr Barnes Original RNSP:
##############################################
73.0 gr RL-15
2417 fps
1.0"
3.610"
##############################################



##############################################
##############################################

IMR 4350:

##############################################
##############################################


260 gr Nosler Ballistic Tip:
##############################################
89.0 gr IMR-4350
2836 fps
0.8"
3.600"
##############################################


300 Nosler Partition:
##############################################
88.0 gr IMR-4350
2704 fps
0.9"
3.565"
##############################################


300 gr Sierra GameKing:
##############################################
88.0 gr IMR-4350
2759 fps
1.0"
3.600"
##############################################


300 gr Bridger Brass FN:
##############################################
88.0 gr IMR-4350
2680 fps
0.8"
3.706"
##############################################


300 gr Bridger Copper FN:
##############################################
87.0 gr IMR 4350
2634 fps
0.5"
3.610"
**********************************************
88.0 gr IMR-4350
2676 fps
1.4"
3.610"
Ejector marks – Do not use
##############################################


300 Bridger Copy of Walterhog:
##############################################
89.0 gr IMR-4350
2719
0.6
3.726"
##############################################


300 gr Barnes XFB Cannelured:
##############################################
87.0 gr IMR-4350
2629 fps
1.0"
3.593"
##############################################


300 gr Hornady FMJ:
##############################################
87.0 gr IMR-4350
2671 fps
1.1"
3.598"
##############################################


350 Barnes Original RNSP:
##############################################
84.0 gr IMR-4350
2502 fps
1.6"
3.610"
##############################################



##############################################
##############################################

H4831SC:

##############################################
##############################################


300 Bridger Brass FN:
##############################################
90 gr H4831SC
2580 fps
0.9"
3.710"
##############################################


300 Bridger Copper FN:
##############################################
90.0 gr H4831SC
2556fps
1.3"
3.610"
##############################################


300 gr Bridger Copy of Walterhog:
##############################################
90.0 gr H4831SC
2508 fps
0.7"
3.730"
##############################################


300 gr Barnes XFB Cannelured:
##############################################
90.0 gr H4831SC
2550 fps
1.8"
3.620"
##############################################


300 gr Hornady FMJ (Ye olde style steel):
################################################
90.0 gr H4831SC
2578 fps
1.6"
3.583"
#############################################


350 gr Barnes Original RNSP:
#############################################
85.0 gr H4831SC
2380 fps
1.5"
3.600"
**********************************************
89.0 gr H4831SC
2454 fps
1.0"
3.600"
##############################################





##############################################
##############################################

Norma MRP:

##############################################
##############################################


300 gr Sierra GameKing:
##############################################
92.0 gr MRP
2742 fps
1.0"
3.600"
**********************************************
93.0 gr MRP
2773 fps
2.5"
3.600"
##############################################


300 gr Bridger Brass FN:
##############################################
91.0 gr MRP
2667 fps
2.5"
3.600"
##############################################


300 gr Bridger Copper FN:
##############################################
91.0 gr MRP
2633 fps
1.0"
3.600"
##############################################


300 gr Bridger Walterhog:
##############################################
89.0 gr MRP
2595 fps
0.6"
3.720"
**********************************************
90.0 gr MRP
2616
0.8"
3.720"
**********************************************
91.0 gr MRP
2641 fps
0.4"
3.720"
##############################################


350 gr Barnes Original RNSP:
##############################################
88.0 gr MRP
2512 fps
1.0"
3.600"
**********************************************
89.0 gr MRP
2540 fps
1.2"
3.600"
**********************************************
90.0 gr MRP
2563 fps
1.5"
3.600"
**********************************************

(All loads were crimped when possible, on cannelure, groove, or between driving bands. The 350 grain Barnes was not crimped.)

Weatherby factory load, .375 Weatherby (Norma brass and primer): Advertised velocity is 2800 fps in a 26” barrel, so the (below) recorded 24”-barrel velocity supports the claim very well:

Unknown Powder (Looks like N-204?) charge weight of 88.5 grains.
300 gr Nosler Partition.
3.565" COL
2734 fps MV (15 feet from muzzle)
1.1" 3-shot group size at 100 yards.



Factory .375 H&H ammo fired in this rifle before and after the conversion from .375 H&H to .375 Weatherby:

Remington (advertised 2530 fps):

Before rechamber:
300 Swift A-Frame
3.555” COL
2473 fps
1.0" 3-shot group at 100 yards

After rechamber to .375 Wby:
2367 fps
0.8" 3-shot group at 100 yards.

This is a practical "trip saver" ammunition interchangeability.

When the point of impact of the above .375 Weatherby factory load is +3.0” at 100 yards, the POI of the above .375 H&H factory load is +1.3” at 100 yards, IN THIS RIFLE.

The Leupold Scope and QRW mounts held up very well, with no loosening or change of POI throughout the testing. Again, these are the latest version, with the square recoil stop on the bottom of each ring. The 6x48 base screws were replaced with the stronger 8x40 screws and red Loctite applied when the rifle was converted to .375 Weatherby.
Or use JB Weld. It comes off easily with a torch.

The above maximum useful loads are likely just below the SAAMI maximum average standard for the .375 Weatherby: 55,152 CUP or 63,861 PSI.

The loads shown with ejector marks may be over this pressure level. Beware of ambient temperature effects. Work up from 10% below the maximum trouble free loads shown. I suspect Norma 204 powder would also be excellent.

Handloaders have the choice of new Norma made Weatherby brass with proper headstamp readily available now. This brass is about 20 grains lighter, and has about 3 grains greater water capacity than my brass formed from Hornady basic. Using the Norma brass will lower pressures and velocities versus these loads in Hornady brass, so 0.5 to 1.0 grains more powder, depending on type powder, might be used in Norma brass. A comparison of brass is shown below, also including the Winchester WW-Super .375 H&H brass that has been fire formed to .375 Weatherby (beware the shorterWW brass):

Norma/ Hornady /WW-Super

2.860/ 2.850 /2.832 (case length in inches)

228.3/ 248.4 /248.7 (case weight in grains)

111.5/ 108.2 /108.4 (overflow water capacity)

Bullet length is a consideration with the monometals. Using a longer magazine of 3.750” would allow the long bullets to be seated out and still function through the magazine, rather than being only single loaded into the chamber. A .375 Weatherby with a longer box than the usual .375 H&H would be an advantage here.

Moly coating might also be considered for possible improvement of some loads.

Finally, here is a list of some bullet lengths measured from those I had on hand:

235 grain Speer SP: 1.043”

235 grain Barnes X: 1.210”

250 grain Swift A-Frame: 1.122”

250 Barnes XFB: 1.272”

250 grain Sierra GameKing: 1.180”

260 grain Nosler Ballistic Tip: 1.384”

260 grain Nosler Partition: 1.146”

265 Groove MI, copper FN solid: 1.345

270 grain Hornady SP: 1.274”

270 grain Speer SPBT: 1.295”

270 grain Barnes XFB Cannelured: 1.345”

270 grain Bridger brass FN solid: 1.323”

285 grain Speer Grand Slam: 1.252”

300 grain Hornady FMJ (steel jacket): 1.247”

300 grain Hornady RNSP: 1.174”

300 grain Sierra GameKing: 1.387”

300 grain Swift A-Frame: 1.297”

300 grain Bridger brass FN solid: 1.473

300 grain Bridger copper FN solid: 1.386”

300 grain Bridger Walterhog: 1.520”

300 grain Barnes XFB Cannelured: 1.472”

300 grain Nosler Partition: 1.337”

300 grain Winchester FMJ (steel jacket): 1.335”

300 grain Winchester Failsafe: 1.455”

300 grain Hornady BTSP: 1.418”

350 grain Barnes Original RNSP, 0.049” jacket: 1.425”

The secrets of loading for the .375 Wby:

Be sure to have a 2001 SAAMI/CIP Spec chamber and throat.
Not the tight custom stuff, nor the overly sloppy 1945 original throat.

Use Norma .375 Wby brass with proper headstamp.
Use the proper 300-grain bullet.
... Use H4350, start at 80.0 grains and work up ... anything over 88.0 grains is likely to be excessive ...

Don't go any faster than 2800 fps in a 26" barrel, or about 2740 fps in a 24" barrel.
Not all bullet and rifle combos will allow that, but some will allow more ... depends on bullet length and magazine box length, COL/COAL ...
5000 ft-lbs of KE is plenty.
The heavier the bullet, the more advantage the .375 Wby has over the .375 H&H.
It really gets good starting with proper 300-grainers and the proper powder.

I think I need to try some newer bullets (North Fork SP/CP/FP, GSC HV/FN, Barnes TSX/BFN, etc.) in a 3.6" COL as well as a 3.8" COL with H4350 Extreme.

The above data is olde, but it is a place to hang your cap,
or a place for me to resume popping my caps.

For any of you .375 Weatherby fans interested. I have a .375 Weatherby Custom Leonard Brownell for sale at a great price. Let me know if you're interested. I'll never shoot it. Mike

Thanks for the info RIP. I picked up some Sierra 300gr BT and will get some H4350. I only have IMR4350, RL15, W760 and Varget at the moment.