Handgun · Wildcat
6mm TCU
The .223 Remington necked up to 6mm — a Thompson/Center Ugalde wildcat popular in Contender silhouette..
- Caliber
- 0.243″ · 6.172 mm
- Introduced
- 1980
- Case
- Rimless
- Parent
- .223 Remington
- Primary use
- Hunting
- Status
- Wildcat
- Introduced
- 1980
- Type
- Handgun
- Origin
- United States
- Inventor
- Wes Ugalde
- Manufacturer
- Handloaded only (wildcat; no factory ammunition)
- Standard
- Wildcat
- Status
- Wildcat
- Availability
- Rare
- Case capacity
- 32.2 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 55,000 psi, SAAMI transducer
- Eff. range
- 200 yd
- Max range
- 3900 yd
- Recoil
- 4–4.3 ft·lb
Ballistics
Velocity only, no drag model: no published ballistic coefficient is on file for 6mm TCU, so this is the shape gravity alone gives the advertised velocity. Drag would steepen it. The tool below solves real loads through their published G1 or G7 model.
Open in Ballistic Compare- Parent case
- .223 Remington
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
reloading data · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 6.17 | 0.243 | ✓ |
| Neck ⌀ | 6.73 | 0.265 | ✓ |
| Shoulder ⌀ | 8.99 | 0.354 | ✓ |
| Shoulder angle | 40° | — | ✓ |
| Base ⌀ | 9.55 | 0.376 | ✓ |
| Rim ⌀ | 9.60 | 0.378 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.14 | 0.045 | ✓ |
| Neck length | 5.92 | 0.233 | ≈ |
| Case length | 44.20 | 1.740 | ✓ |
| Overall length | 57.15 | 2.250 | ✓ |
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. 6mm TCU is highlighted below.
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.
Lineage
Connected reference
History
The 6mm TCU was introduced in 1980 by Wes Ugalde, based on the .223 Remington case.
FAQs
- What twist rate does 6mm TCU use?
- 6mm TCU typically uses a 1:10 twist rate.
- What bullet diameter is 6mm TCU?
- 6mm TCU uses a 0.243″ (6.172 mm) diameter bullet.
- Is 6mm TCU still in production?
- 6mm TCU is wildcat; typical availability is rare.
- What is 6mm TCU used for?
- 6mm TCU is primarily used for hunting.
- What is 6mm TCU based on?
- 6mm TCU is derived from the .223 Remington case.
Sources & provenance
- Manufacturer Hornady — Hornady Obsolete Load Data — 6mm TCU (handgun) · bullet ⌀, grain weights, velocity archived
- Secondary Wikipedia (pointer) — Thompson/Center Ugalde · parent_cartridge, year archived
- Secondary Lee Precision — 6mm TCU dies (formed by necking up .223) · parent_cartridge
Data & sources. Specs compiled from the Lindcott Armory reference; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →
