.50 Cal Muzzleloader Internal Bore Guide

This .50 caliber muzzleloader bore guide is designed to fit inside the muzzle, not over the barrel, ensuring precise ramrod alignment while fully protecting the crown during loading and cleaning.

The design uses a two-material system:

• A rigid PETG inner core for straight, durable ramrod guidance
• A flexible TPU outer sleeve that centers the guide in the bore and provides a soft, non-marring interface with the muzzle

Unlike over-the-barrel guides, this design rests directly on the crown via an integrated TPU flange, keeping pressure off the barrel exterior and ensuring repeatable alignment. The PETG retention flange locks into the TPU sleeve for mechanical retention—no glue required.

This guide was designed, printed, and test-fit on an actual .50 caliber muzzleloader and confirmed to work properly with a removable ramrod and threaded jag.

Key Features

• Internal-fit design for .50 caliber muzzleloaders
• Protects flat muzzle crowns during loading and cleaning
• PETG core for rigidity and straight ramrod alignment
• TPU sleeve for centering, grip, and non-marring contact
• Integrated flange rests on muzzle crown (no internal bevel)
• Mechanical retention between PETG core and TPU sleeve
• No adhesives required

Dimensions & Specifications

PETG Core

• Ramrod hole: 9.6 mm
• Outer diameter (shaft): 11.0 mm
• Retention flange diameter: 14–15 mm
• Retention flange height: 2.5 mm
• Total height (including flange): 22.5 mm
• Bottom edge includes a chamfer to aid insertion into TPU sleeve

TPU Sleeve

• Inner diameter: 11.1 mm
• Outer diameter: 12.5 mm
• Sleeve depth: 20 mm
• Integrated flange:
  • Height: 2.5 mm
  • Diameter: 22 mm
• No internal bevel at flange (designed for flat crowns)

Recommended Materials

• Inner Core: PETG
• Outer Sleeve: TPU (95A recommended)

Print Settings (Recommended)

PETG Core

• Layer height: 0.2 mm
• Walls: 3–4
• Infill: 20–30%
• Supports: Not required
• Orientation: Vertical (ramrod hole vertical)

TPU Sleeve

• Layer height: 0.2–0.28 mm
• Walls: 3
• Infill: 15–20%
• Supports: Not required
• Orientation: Vertical

Assembly

1. Press the PETG core into the TPU sleeve from the top
2. The chamfered PETG base helps guide insertion
3. PETG retention flange seats against the TPU sleeve flange
4. No glue needed

Compatibility Notes

• Designed for .50 caliber muzzleloaders
• Intended for flat or lightly dressed crowns
• Works with removable ramrods and threaded jags
• Always verify fit before use; tolerances may vary slightly by printer and filament

Safety Disclaimer

This accessory is intended to protect the muzzle crown during loading and cleaning only. Always follow proper firearm safety procedures and ensure the firearm is unloaded before use.