.300 Winchester Magnum
The benchmark belted magnum. Flat trajectory and massive energy. Capable of taking any North American big game at extended ranges. Popular with military snipers for anti-personnel use beyond 1000 yards. Significant recoil — not for beginners.
Best For
Ballistics (Typical Factory Load)
🔧 Handloading Data
Reference load data for experienced reloaders. Always start at the start charge and work up. Consult official manuals before loading.
| Bullet | Powder | Start | Max | Velocity | COAL | Source |
|---|---|---|---|---|---|---|
| 180 gr (11.7 g) SPBT | Hodgdon H1000 | 72.0 gr 4.67 g |
78.0 gr 5.05 g |
3,050 fps | 3.600 | Hodgdon |
| 180 gr (11.7 g) SPBT | Alliant Reloder 22 | 71.0 gr 4.6 g |
77.0 gr 4.99 g |
3,020 fps | 3.600 | Alliant |
| 180 gr (11.7 g) SPBT | IMR 7828 SSC | 72.0 gr 4.67 g |
77.5 gr 5.02 g |
3,040 fps | 3.600 | IMR |
| 200 gr (13.0 g) HPBT | Hodgdon Retumbo | 71.0 gr 4.6 g |
76.0 gr 4.92 g |
2,850 fps | 3.600 | Hodgdon |
| 200 gr (13.0 g) HPBT | Alliant Reloder 25 | 70.0 gr 4.54 g |
75.0 gr 4.86 g |
2,820 fps | 3.600 | Alliant |
| 220 gr (14.3 g) SPBT | Hodgdon H1000 | 69.0 gr 4.47 g |
74.0 gr 4.8 g |
2,700 fps | 3.600 | Hodgdon |
📐 Measurement Guide for Reloaders
Measured in grains (1 grain ≈ 0.065 grams) using precision digital or mechanical scales. Maintaining strict powder weight is crucial for safety and velocity consistency.
Total length from case base to bullet tip. Checked with digital calipers. Must be within manufacturer's specified range to fit and feed from your firearm's magazine.
Precision shooters measure to the ogive — the curved part of the bullet that first contacts the rifling — for more accurate bullet seating depth and consistency.
Brass stretches with firing. Measure case length to know when to trim. Use headspace comparators to check shoulder bump-back during sizing.
The grip the brass has on the bullet. Measured with ball micrometers by comparing neck wall thickness before and after bullet seating.
Inspect fired brass for over-pressure: flattened primers, ejector marks, case head expansion. If unsure, reduce charge and consult your load manual.
⚠️ Always consult established reloading manuals (Hodgdon, Hornady, Lyman) for your specific bullet and powder combinations. For experienced reloaders only.
Technical Specifications
| Bullet Diameter | 7.82 mm |
| Case Length | 77.57 mm |
| Max Chamber Pressure | 64,800 PSI |
| Type | Rifle |