The 6 Dasher (frequently called the 6mm Dasher) is one of the most successful and dominant precision long-range competition cartridges in the world, frequently ruling the podium in thousand-yard benchrest, F-Class, and Precision Rifle Series (PRS) matches! Created as a wildcat variation based on the exceptional 6mm BR Norma parent case, it features a shoulder blown forward by 100 thousandths of an inch and improved with a sharp 40-degree shoulder angle. This design efficiently balances powder capacity with bore volume, allowing it to drive heavy, high-ballistic-coefficient 243-thousandths-inch projectiles at velocities near 2-thousand 900 feet per second while maintaining exceptional barrel life and minimal recoil.
6 Dasher Case Dimensions Overview
| Dimension Property | Specification (Imperial) | Specification (Metric) |
| Parent Case | 6mm BR Norma | 6mm BR Norma |
| Bullet Diameter | 243 thousandths in | 6 mm and 2 tenths |
| Case Length | 1 inch and 546 thousandths | 39 mm and 27 hundredths |
| Case Trim Length | 1 inch and 535 thousandths | 38 mm and 99 hundredths |
| Overall Length (COAL) | 2 inches and 420 thousandths (Max) | 61 mm and 47 hundredths |
| Rim Diameter | 473 thousandths in | 12 mm |
| Rim Thickness | 54 thousandths in | 1 mm and 37 hundredths |
| Base Diameter | 469 thousandths in | 11 mm and 9 tenths |
| Shoulder Diameter | 462 thousandths in | 11 mm and 73 hundredths |
| Neck Diameter | 271 thousandths in | 6 mm and 9 hundredths |
| Shoulder Angle | 40 degrees | 40 degrees |
| Case Capacity | Approx 41 grains and 5 tenths water | 2 cubic cm and 69 hundredths |
| Maximum Average Pressure | 60-thousand psi | 414 megapascals |
Understanding the 6 Dasher Case Dimensions
- Wildcat Heritage: Developed from the hyper-accurate 6mm BR family by pushing the shoulder forward and introducing a steep wall profile;
- Sharp Shoulder Angle: Utilizes a distinct 40-degree shoulder angle that promotes clean, uniform powder ignition and reduces case stretching during firing cycles;
- Optimized Capacity: Holds approximately 41 grains and 5 tenths of water, providing an ideal powder volume for efficient medium-burn-rate propellants;
- Match-Grade Precision: Engineered specifically to seat long, high-BC bullets out in the neck region, preventing interference with the powder column and maximizing consistency.
6 Dasher Case Dimensions in Inches and Millimeters
| Measurement Point | Max (Inches) | Min (Inches) | Max (Millimeters) | Min (Millimeters) |
| Case Length | 1 and 546 thousandths | 1 and 535 thousandths | 39 and 27 hundredths | 38 and 99 hundredths |
| Trim-To Length | 1 and 535 thousandths | None | 38 and 99 hundredths | None |
| Rim Diameter | 473 thousandths | 463 thousandths | 12 mm | 11 and 76 hundredths |
| Base Diameter | 469 thousandths | 464 thousandths | 11 and 9 tenths | 11 and 79 hundredths |
| Shoulder Diameter | 462 thousandths | 458 thousandths | 11 and 73 hundredths | 11 and 63 hundredths |
| Neck Diameter | 271 thousandths | 267 thousandths | 6 and 9 tenths | 6 and 78 hundredths |
| Bullet Diameter | 243 thousandths | 241 thousandths | 6 and 2 tenths | 6 and 12 hundredths |
| Overall Length (COAL) | 2 and 420 thousandths | 2 and 250 thousandths | 61 and 47 hundredths | 57 and 15 hundredths |
6 Dasher Case Length and Trim Specifications
The maximum case length of the 6 Dasher is 1 inch and 546 thousandths (39 mm and 27 hundredths), with a recommended trim-to length of 1 inch and 535 thousandths (38 mm and 99 hundredths). Because of its sharp 40-degree shoulder, case growth during firing is exceptionally minimal compared to traditional bottleneck cartridges, meaning reloaders spend significantly less time trimming brass.
6 Dasher Base and Rim Dimensions
The 6 Dasher inherits its robust, reliable foundation directly from the 6mm BR Norma lineage:
- Rim Diameter: 473 thousandths in (12 mm)
- Base Diameter: 469 thousandths in (11 mm and 9 tenths)
- Rim Thickness: 54 thousandths in (1 mm and 37 hundredths)
This standard small-rifle primer footprint ensures solid extraction and smooth bolt thrust performance in custom benchrest and competition actions.
6 Dasher Shoulder and Neck Dimensions
- Shoulder Angle: A sharp 40-degree angle provides a defined headspace datum and enhances propellant combustion efficiency;
- Shoulder Diameter: Measures 462 thousandths in where the body transitions upward toward the neck;
- Neck Length & Diameter: Features a generous neck measuring 271 thousandths in at the mouth, offering excellent grip surface for heavy, long-range match bullets.
6 Dasher Case Capacity and Performance
The internal case capacity of the 6 Dasher averages roughly 41 grains and 5 tenths of water, giving it a slight capacity edge over its parent 6mm BR case. This volume pairs brilliantly with slow-to-medium powders like Hodgdon Varget, IMR 8208 XBR, and Hodgdon H4895, easily pushing 105-grain to 109-grain match bullets to velocities near 2-thousand 850 to 2-thousand 950 feet per second with extreme node stability.
6 Dasher Dimensions vs Similar Cartridges
| Cartridge | Bullet Diameter | Case Length | COAL | Max Pressure |
| 6 Dasher | 243 thousandths | 1 and 546 thousandths | 2 and 420 thousandths | 60-thousand psi |
| 6mm BR Norma | 243 thousandths | 1 and 560 thousandths | 2 and 440 thousandths | 58-thousand 740 psi |
| 6mm GT | 243 thousandths | 1 and 725 thousandths | 2 and 480 thousandths | 60-thousand psi |
| 6mm Creedmoor | 243 thousandths | 1 and 920 thousandths | 2 and 740 thousandths | 62-thousand psi |
| 223 Remington | 224 thousandths | 1 and 476 thousandths | 2 and 260 thousandths | 55-thousand psi |
Chamber and Reamer Dimensions
Chamber specifications for the 6 Dasher are traditionally custom-ordered via reamer prints because the cartridge began as a wildcat. Most match chambers feature a freebore length ranging between 100 thousandths and 125 thousandths of an inch to properly accommodate long, high-BC bullets like the Berger 105-grain VLD or 109-grain Long Range Hybrid without intruding too deeply into the powder space.
Common Questions
- How do you form 6 Dasher brass?While factory-formed 6 Dasher brass is now readily available from top manufacturers like Lapua, Peterson, and Alpha Munitions, handloaders traditionally fire-formed standard 6mm BR brass by loading a standard charge and firing it once in a Dasher chamber!
- What is the standard twist rate for 6 Dasher dimensions? A 1 in 7 inch or 1 in 7 inch and 5 tenths twist rate is standard for modern barrels, ensuring high-speed gyroscopic stability for heavy, aerodynamically efficient long-range bullets.
- Why is the 6 Dasher so popular in precision shooting?Its combination of ultra-low recoil, high barrel life, exceptional powder efficiency, and incredible consistency at distances out to one thousand yards makes it a favorite among competitive long-range shooters!