Rifle · SAAMI
.204 Ruger
Extremely fast .20 caliber varmint round.
- Caliber
- 0.2039″ · 5.18 mm
- Introduced
- 2004
- Case
- Rimless
- Parent
- .222 Remington Magnum
- Primary use
- Varmint, Target
- Status
- Active
- Introduced
- 2004
- Type
- Rifle
- Origin
- United States
- Inventor
- Hornady / Ruger
- Manufacturer
- Hornady
- Standard
- SAAMI
- Status
- Active
- Availability
- Common
- Case capacity
- 32.5 gr H₂O
- Twist (typical)
- 1:12
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 57,500 psi, SAAMI transducer
- Eff. range
- 450 yd
- Max range
- 3200 yd
- Recoil
- 4–6.5 ft·lb
Introduced by Hornady
Ballistics
Published velocity/energy data isn't available for .204 Ruger. Parent case: .222 Remington Magnum.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
CIP TDCC · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 5.18 | 0.204 | ✓ |
| Neck ⌀ | 5.87 | 0.231 | ✓ |
| Shoulder ⌀ | 9.14 | 0.360 | ✓ |
| Shoulder angle | 30° | — | ✓ |
| Base ⌀ | 9.56 | 0.376 | ✓ |
| Rim ⌀ | 9.60 | 0.378 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.14 | 0.045 | ✓ |
| Neck length | 5.08 | 0.200 | ≈ |
| Case length | 46.99 | 1.850 | ✓ |
| Overall length | 57.40 | 2.260 | ✓ |
Size vs familiar rounds
Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .204 Ruger is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
10 reloading powders listed for .204 Ruger, fastest to slowest. Cross-reference in the finder →
Reloading costestimate cost per round vs factory
Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.
Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.
Firearms chambered in .204 Ruger
Lineage
Connected reference
History
Jointly developed by Hornady and Ruger in 2004 as modern varmint cartridge. Based on .222 Remington Magnum case necked to .204. Designed to provide .220 Swift-like velocity with less powder, barrel wear, and recoil. Quickly gained popularity among varmint hunters. Fills niche between .17 and .22 calibers. Excellent ballistics with minimal recoil and barrel wear.
FAQs
- What twist rate does .204 Ruger use?
- .204 Ruger typically uses a 1:12 twist rate.
- What bullet diameter is .204 Ruger?
- .204 Ruger uses a 0.2039″ (5.18 mm) diameter bullet.
- Is .204 Ruger still in production?
- .204 Ruger is active; typical availability is common.
- What is .204 Ruger used for?
- .204 Ruger is primarily used for varmint, target.
- What is .204 Ruger based on?
- .204 Ruger is derived from the .222 Remington Magnum case.
- What are the best powders for .204 Ruger?
- Reloading powders commonly listed for .204 Ruger include Ramshot X-Terminator, Power Pro Varmint, N530, N130, among 10 suitable options.
Sources & provenance
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
- Standard C.I.P. — C.I.P. TDCC — Tables of Dimensions of Cartridges and Chambers
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 66 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
