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
- 2019
- Case
- Rimless
- Parent
- 6.5x47mm Lapua
- Primary use
- Competition, Target
- Status
- Active
- Introduced
- 2019
- Type
- Rifle
- Origin
- United States
- Inventor
- George Gardner / Tom Jacobs
- Manufacturer
- Hornady / Various
- Standard
- SAAMI
- Status
- Active
- Availability
- Common
- Case capacity
- 43.4 gr H₂O
- Twist (typical)
- 1:7.5
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 62,000 psi, SAAMI transducer
- Eff. range
- 1200 yd
- Max range
- 5750 yd
- Recoil
- 5–8 ft·lb
Ballistics
Published velocity/energy data isn't available for 6GT. Parent case: 6.5x47mm Lapua.
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
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. It was later standardized by SAAMI (listed in ANSI/SAAMI Z299.4-2025 as 6mm GT).
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 6.5x47mm Lapua 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 →
