6 x 45 mm Load Data & Reloading Guide
Also known as: 6x45mm, 6mm x 45
About 6 x 45 mm
The 6 x 45 mm caliber, also known as the .243 Super X in some circles, is a wildcat cartridge that originated from the popular .223 Remington casing, necked up to accept a 6 mm bullet. This caliber was developed in response to the growing demand for small to medium game hunting and competition shooting, providing an alternative to larger calibers for those looking for versatility and performance in a lightweight package.
Technically, the 6 x 45 mm offers impressive ballistic characteristics for its size. With a case length of 45 mm, it accommodates a variety of bullet weights typically ranging from 55 to 90 grains. This flexibility allows shooters to tailor their loads to specific needs, optimizing for velocity and energy retention. The cartridge is known for its moderate recoil and efficient powder use, making it a favorable choice for precision shooting and regular practice without excessive fatigue or expense.
In terms of performance, the 6 x 45 mm is recognized for its flat trajectory and effective range out to about 300 yards, which makes it suitable for varmint hunting and target shooting. It offers sufficient stopping power for small to medium-sized game while maintaining accuracy. The caliber's ability to handle various bullet designs also enhances its versatility, adapting well to different shooting sports and environments.
For reloaders, the 6 x 45 mm presents several advantages. Its foundation on the ubiquitous .223 Remington case makes sourcing brass relatively straightforward. Moreover, the reloading process is uncomplicated, allowing experimentation with bullet types and weights to fine-tune performance according to specific goals. This level of customization appeals to precision shooters and enthusiasts who seek to optimize each cartridge load for different scenarios, offering a customized shooting experience without deviating significantly from standard reloading practices.
Technical Drawing

Technical Specifications
Start Calculating to Develop your own Load Data for 6 x 45 mm
Use our professional ballistics calculator to develop safe and accurate load recipes for 6 x 45 mm.
Start CalculatingBrass Case Capacities
The following table shows the case capacity (Grains of Water) for brass in cartridge 6 x 45 mm where we have data (number of datapoints in brackets).
Standard Load Data — 6 x 45 mm
Select your desired cartridge and bullet weight below to access the corresponding load table. From there, you can choose any listed load recipe and transfer it directly into the ballistics calculator for further refinement, optimization, and precision tuning.
.243 | 90gr | Sierra FMJBT GameKing
.243 | 105gr | Geco SOFTPOINT
.243 | 100gr | MEN SP
.243 | 100gr | Winchester Soft-Point
.243 | 100gr | MEN FMJ
.243 | 96gr | Brenneke TOG
.243 | 95gr | ShellHouse Castings SP Hard Cast
.243 | 85gr | Frontier PH HPFB
.243 | 85gr | Barnes TSX BT
.243 | 75gr | AERO SB-SR,- smax:13.10
.243 | 75gr | Reichenberg Spezial Jagd
.243 | 70gr | Merlin Virtus
.243 | 77gr | IBEX TRD
.243 | 85gr | MEN SPBT
.243 | 90gr | Speer FMJ
.243 | 64gr | Berger Target
.243 | 100gr | Speer Boat-Tail
.243 | 85gr | Speer Boat-Tail
.243 | 70gr | Berger Target FB
.243 | 70gr | Osprey Virtus
.243 | 65gr | CutEdge ESP Raptor
.243 | 77gr | Reichenberg Solid Spezial
.243 | 90gr | Speer Deep Curl Soft Point
.244 | 77gr | Lapua Scenar-L
Community Loads — 6 x 45 mm
Here are some popular loads for 6 x 45 mm:
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| Bullet | Powder | Barrel (in) | Charge (gr) | Case Volume (GoW) | OAL (in) | Max. Pressure (psi) | Muzzle Velocity (fps) | |
|---|---|---|---|---|---|---|---|---|
.243 | 70gr | Sierra MatchKing (70gr) | Vihtav N133 | 26.0 | 22.0 | 30.5 | 2.26 | 34,065 (62%) | 2677 | |
M.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 30.5 | 2.26 | 53,345 (97%) | 2933 | |
M.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 28.8 | 2.24 | 49,908 (91%) | 2848 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 30.5 | 2.26 | 46,195 (84%) | 2831 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 28.8 | 2.24 | 46,499 (84%) | 2795 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 28.8 | 2.30 | 44,280 (80%) | 2772 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | ••.• | 30.5 | 2.26 | 38,290 (69%) | 2684 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | 19.0 | 30.5 | 2.26 | 35,389 (64%) | 2628 | |
.243 | 75gr | Sierra VarmintKing (75gr) | ADI AR 2207 | 24.0 | 19.2 | 28.8 | 2.40 | 44,788 (81%) | 2736 | |
M.243 | 87gr | Hornady V-MAX (87gr) | Vihtav N133 | 26.0 | ••.• | 30.8 | 2.36 | 54,244 (98%) | 2710 |
Frequently Asked Questions
The maximum pressure for 6 x 45 mm is 55,114 psi | 3,800 bar.
6 x 45 mm typically uses a Large Rifle (LR) primer.
The case capacity of 6 x 45 mm is approximately 30.5 grains of water (H₂O).