.338 Lapua Magnum Cartridge

The .338 Lapua Magnum (8.6×70 mm or 8.58×70 mm) is a rimless, bottlenecked, centerfire rifle cartridge. It was developed during the 1980s as a high-powered, long-range cartridge for military snipers. It was used in the War in Afghanistan and the Iraq War. As a result of this, it has become widely available.

The loaded .338 cartridge is 14.93 mm (0.588 in) in diameter (rim) and 93.5 mm (3.68 in) long. It can penetrate better-than-standard military body armor at ranges of up to 1,000 meters (1,090 yds) and has a maximum effective range of about 1,750 meters (1,910 yds) with C.I.P. conforming ammunition at sea level conditions. Muzzle velocity is dependent on barrel length, seating depth, and powder charge, and varies from 880 to 915 m/s (2,890 to 3,000 ft/s) for commercial loads with 16.2-gram (250 gr) bullets, which corresponds to about 6,525 J of muzzle energy.

Printing Tips

Print with random seam positioning (Prusa Slicer > Print Settings > Layers and perimeters > Advanced > Seam position > Random).

Model Format

The model is available in .STL .STEP and Fusion360 (.F3D) format. 

• STL and STEP files can be used in your typical Slicer Software like PrusaSlicer
• The F3D format contains the original sketch for easy customization in Fusion360

Use as Dummy Round / Snap Cap

3D printed models based on CIP cartridge dimensions are not ideal to fit or be used in real guns. Printed with non-elastic filaments like PETG or PLA, the cartridge is going to break if hit by the bolt. To create usable Snap Caps, I made the modified version (-MOD). 

The -MOD file is a modified version with the following changes:

• Modifications for better printability
• Slightly smaller dimensions to fit into real guns
• Primer Pocket (Print LR.stl using flexible Filament like FilaFlexible40 as a primer. If you don't have a reloading press, you might want to scale it down to 96%)
• Drill Hole (7/64 or 3mm) inside the Primer Pocket. The Drill hole is intended to be fixed on a drill to sand and polish the model, creating a nice looking shiny finish.