Rifle · SAAMI
6GT
Purpose-built PRS competition cartridge designed for optimal performance with heavy-for-caliber 6mm bullets.
- Caliber
- 0.243″ · 6.172 mm
- Introduced
- 2021
- Case
- Rimless
- Parent
- 6.5x47mm Lapua
- Primary use
- Competition, Target
- Status
- Active
- Introduced
- 2021
- Type
- Rifle
- Origin
- United States
- Inventor
- George Gardner / Tom Jacobs
- Manufacturer
- Hornady / Various
- Standard
- SAAMI
- Status
- Active
- Availability
- Common
- Case capacity
- 46.5 gr H₂O
- Twist (typical)
- 1:7.5
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 63,000 psi
- Eff. range
- 1200 yd
- Max range
- 3500 yd
- Recoil
- 5–8 ft·lb
Ballistics
Published velocity/energy data isn't available for 6GT. Parent case: 6.5 Creedmoor.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
SAAMI · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.17 | 0.243 | ✓ |
| Neck ⌀ | 6.93 | 0.273 | ✓ |
| Shoulder ⌀ | 11.66 | 0.459 | ✓ |
| Shoulder angle | 35° | — | ✓ |
| Base ⌀ | 11.95 | 0.470 | ✓ |
| Rim ⌀ | 11.96 | 0.471 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.37 | 0.054 | ~ |
| Neck length | 7.32 | 0.288 | ≈ |
| Case length | 43.82 | 1.725 | ✓ |
| Overall length | 67.06 | 2.640 | ~ |
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. 6GT is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
1 reloading powder listed for 6GT, 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 6GT
5 models in the database chamber 6GT. Browse all →
Lineage
Connected reference
History
Developed by George Gardner of GA Precision and Tom Jacobs of Vapor Trail Bullets specifically for Precision Rifle Series competition in semi-automatic rifles. The goal was a cartridge that fed reliably from AR-10 pattern magazines while shooting the heaviest, highest-BC 6mm bullets with less recoil than 6mm Creedmoor. Submitted to SAAMI and standardized in 2021 — unusually fast adoption for a competition-born cartridge.
FAQs
- What twist rate does 6GT use?
- 6GT typically uses a 1:7.5 twist rate.
- What bullet diameter is 6GT?
- 6GT uses a 0.243″ (6.172 mm) diameter bullet.
- Is 6GT still in production?
- 6GT is active; typical availability is common.
- What is 6GT used for?
- 6GT is primarily used for competition, target.
- What is 6GT based on?
- 6GT is derived from the 6.5 Creedmoor case.
- What are the best powders for 6GT?
- Reloading powders commonly listed for 6GT include LT-32.
Sources & provenance
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
- Secondary NRA — Shooting Sports USA (SSUSA) — What is 6 mm GT? · parent_cartridge archived
- Secondary 6GT — New Cartridge, Alpha Brass (AccurateShooter Forum) · parent_cartridge
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 14 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →