338 Federal vs 308 compares two cartridges on the same case. The 338 Federal is the 308 Winchester case necked up to .338 inch, so both share case length, bolt face, action length and magazine size. The 308 fires 150 to 180 gr .308-inch bullets that shoot flatter at long range; the 338 Federal fires 180 to 210 gr .338-inch bullets that carry more energy and more frontal area inside about 300 yards. Chattahoochee Munitions manufactures both on its CM10 large-frame semi-automatic platform.
338 Federal vs 308 Specifications
| Specification | 338 Federal | 308 Winchester |
|---|---|---|
| Introduced | 2006, Federal with Sako | 1952, Winchester |
| Bullet diameter | .338 inch | .308 inch |
| Case length | 2.015 inches | 2.015 inches |
| Maximum average pressure (SAAMI) | 62,000 psi | 62,000 psi |
| Typical hunting bullets | 180 to 210 gr | 150 to 180 gr |
| CM10 barrel and twist | 18-inch 416R, 1:10 | 12.5, 16 and 18-inch, 1:10 (CM10-SD 1:5) |
Dimensions follow the ANSI/SAAMI centerfire rifle standard.
338 Federal vs 308 Energy
Published 24-inch muzzle figures: Federal lists the 338 Federal 185 gr Barnes Triple-Shock X at 2,750 fps and the 210 gr Nosler Partition at 2,630 fps; Hornady lists the 308 Winchester 178 gr ELD-X at 2,600 fps and the 150 gr SST at 3,000 fps. Energy is calculated from weight and velocity; 18-inch values are Chattahoochee Munitions estimates at 30 fps per inch below 24 inches, not chronograph data.
| Load | 24-inch velocity | 24-inch energy | 18-inch velocity (est.) | 18-inch energy (est.) |
|---|---|---|---|---|
| 338 Federal 210 gr Partition | 2,630 fps | 3,226 ft-lb | 2,450 fps | 2,800 ft-lb |
| 338 Federal 185 gr Triple-Shock X | 2,750 fps | 3,107 ft-lb | 2,570 fps | 2,714 ft-lb |
| 308 Win 178 gr ELD-X | 2,600 fps | 2,672 ft-lb | 2,420 fps | 2,314 ft-lb |
| 308 Win 150 gr SST | 3,000 fps | 2,997 ft-lb | 2,820 fps | 2,648 ft-lb |
At the muzzle the 338 Federal carries roughly 15 to 20 percent more energy than common 308 hunting loads, and it does it with a heavier, wider bullet. That weight is what elk and moose hunters want when a shot has to go through heavy muscle and bone.
338 Federal vs 308 Trajectory
The 308 shoots flatter past about 300 yards. Its sleek 168 to 178 gr bullets have higher ballistic coefficients than typical 338 Federal hunting bullets, and match ammunition for long range is plentiful. The 338 Federal’s blunter, heavier hunting bullets slow down faster. Inside 300 yards the difference in drop is a few inches, which is why the 338 Federal is a woods and mixed-country cartridge and the 308 is the more natural long-range choice. For long-range numbers on the 308 side, see 308 ballistics.
338 Federal vs 308 Recoil
The 338 Federal recoils more than the 308 because it pushes a heavier bullet at similar velocity. In the CM10, which weighs 7 lb 14 oz before optics and has an adjustable gas block and adjustable buffer, the gas system absorbs part of that, and a muzzle brake can absorb more. Both CM10s ship with an optional muzzle brake selection or a thread protector.
338 Federal vs 308 for Hunting
- Deer and hogs: both are well suited.
- Elk and moose: the 338 Federal is the stronger choice with 200 to 210 gr bullets.
- Black bear: 338 Federal is suitable with a well-constructed bullet. Chattahoochee Munitions does not recommend 308 for bear.
- Grizzly and brown bear: Chattahoochee Munitions points hunters to 458 SOCOM XL.
338 Federal vs 308 Ammunition
The 308 has a large selection of factory ammunition, including match, hunting and surplus. 338 Federal ammunition is made in smaller runs and costs more per round, so buy enough of one load to zero and hunt with. The 308 also has a dedicated subsonic option at Chattahoochee Munitions: the 308 subsonic AR10 (CM10-SD, subsonic only). The CM10 338 Federal is supersonic; for subsonic .338 shooting see 338 Federal vs 8.6 Blackout.
338 Federal vs 308 in the CM10
Both rifles use the CM10 billet 7075-T6 receivers, a Superlative Arms adjustable gas block, an adjustable buffer and 5/8×24 muzzle threads, in Black Tungsten, Cobalt Kinetics Green or FDE Metallic Cerakote. The 338 Federal uses an 18-inch 416R stainless 1:10 barrel and the CM10 10-round magazine for 6.5 Creedmoor, 7mm-08, 338 Federal and 358 Winchester. The 308 comes in 12.5, 16 and 18 inches; see District 308 and What is 338 Federal.
More Variant Valley Guides
- What is 6.5 Creedmoor?
- 6.5 Creedmoor ballistics
- 6.5 Creedmoor barrel length
- 6.5 Creedmoor twist rate
- 6.5 Creedmoor for hunting
- 7mm-08 vs 6.5 Creedmoor
- What is 7mm-08?
- 7mm-08 vs 308
- What is 338 Federal?
- 338 Federal vs 8.6 Blackout
- What is 358 Winchester?
- 338 Federal vs 358 Winchester vs 7mm-08
- 308 Winchester cartridge family
- 308 vs 6.5 Creedmoor
- 6mm ARC vs 6.5 Creedmoor
- 6.5 Grendel vs 6.5 Creedmoor
338 Federal vs 308 FAQ
Does 338 Federal hit harder than 308?
Yes at the muzzle. Published 338 Federal loads carry about 3,100 to 3,200 ft-lb from 24-inch barrels against about 2,700 to 3,000 ft-lb for common 308 hunting loads.
Does 338 Federal shoot flatter than 308?
No. The 308 shoots flatter past about 300 yards with its higher-BC bullets.
Does 338 Federal kick more than 308?
Yes, because it fires a heavier bullet at similar velocity.
Can a 338 Federal use 308 magazines?
The cartridges share case length and body. Chattahoochee Munitions ships the CM10 338 Federal with a factory Magpul PMAG 10 LR/SR GEN M3 that it has tested and verified for 338 Federal.
Who makes a 338 Federal AR10?
Chattahoochee Munitions manufactures the CM10 338 Federal AR10 with an 18-inch 416R stainless 1:10 barrel in three Cerakote finishes.