Reloading The .378 Weatherby Magnum

Posted on: Wednesday January 6, 2021
Reloading The .378 Weatherby Magnum
MD Smith

MD Smith

Loads for .378 Weatherby Magnum:

(Note: These are near maximum loads, you should use 10% less to start.)

(See note on Powders below or read all about various

Due to different barrel lengths, type of bullet, seating depth, primer type
and other factors, you may not get near the FPS charted. It is just a guide
and the reason you should start under these charges and work up.

235 grain JFP (Jacketed Flat Point)
H450 117 gr. 3,147 FPS
H4350 109 gr. 3,224
270 grain Hornady JSP (Jacketed Soft Point)
H4831 115.0 gr. 3,102 FPS
Reloader 19 110.8 gr. 3,110
300 grain Barnes Solid
Reloader 19 108.6 gr. 2,960 FPS
Reloader 22 114.0 gr. 2,965

Discussion: Only Alliant (Reloader 19 and 22) and Hodgden (H450 and H4350)
show loads for the .378 Mag. I have never shot one, but I included these
charges here just because of the sheer power of a 300 grain bullet moving at
3,000 Feet Per Second. Talk about stopping power!

Bullseye, Unique, 2400 and the RELOADER series, are products of Alliant
(formerly Hercules) Powders. Clays, Universal, HP38, HS6, H4895, H450 and
H4350 are products of Hodgdon Powders.

References: Accurate Arms Co. 1996 Reloading booklet – – Alliant Powder Co.
Reloaders’ Guide (1995) – – Hodgdon’s Basic Reloaders Manual (1996) – – Speer
Reloading Manual, #12 – – Winchester Reloading Components Manual, 14th edition
– – Lyman Piston & Revolver Reloading Handbook, 2nd edition. – – VihtaVuori Oy
Company, reloading booklet (1995) – – Numerous magazine articles on reloading
special calibers and personal loads where noted.