Hornady Neck Turning Mandrel — .17 Caliber (391908 | UPC 090255919080)
Achieve match-grade concentricity and uniform neck tension for tiny-bore precision. The Hornady® .17 Caliber Neck Turning Mandrel (391908) is a purpose-built steel mandrel designed to work with the Hornady neck turner system, supporting the case neck from the inside while you skim-cut the outside. The result is consistent neck wall thickness, improved bullet release, and tighter groups—exactly what .17-cal shooters need for varmint work and long-range rimfire-like accuracy with centerfire performance.
Why Use a Neck Turning Mandrel for .17 Caliber?
Uniform Neck Walls = Consistent Tension: Variations in brass thickness can cause irregular bullet grip. A proper mandrel centers and supports the neck so the cutter can produce even wall thickness for repeatable neck tension.
Better Concentricity: By eliminating high spots and asymmetry, neck turning reduces runout—helping bullets align with the bore for smaller SD/ES and tighter groups.
Cleaner Bullet Release: More consistent necks mean a more consistent release impulse, which is critical in small calibers where minor variations show up at distance.
Optimized for the .17s: The .17 bore punishes sloppy brass prep. A caliber-specific mandrel helps you build the highest-precision micro-bore loads for coyotes, fox, and prairie dogs.
Key Features
Caliber-Specific Design: Precisely machined for .17 caliber case necks to pair with Hornady neck turning gear.
Hardened Steel Construction: Durable, dimensionally stable, and resistant to wear for long service life.
True Running Support: Centers the neck from inside the case to give your outside neck turner a stable, chatter-free cutting surface.
Drop-In Compatibility: Works with Hornady neck turning tool bodies (sold separately).
Repeatable Results: Helps achieve uniform neck thickness across lots of brass for match-grade consistency.
Ideal For
Precision Varmint Loads: .17 centerfire platforms where first-round, small-target hits matter.
Competition & Practice: Any .17-cal reloader chasing low runout and uniform seating pressure.
Brass Sorting & Prep: Standardize mixed-lot brass or elevate premium brass to the next level of uniformity.
How It Works (High-Level Overview)
Mandrel In, Cutter Out: The mandrel supports the inside of the neck while the outside turner lightly skims the neck exterior.
Set Your Cut: Adjust the neck turner for the minimal material removal required to even up wall thickness.
Turn Smoothly: Rotate with steady pressure. The mandrel’s polished surface helps maintain concentric support for clean results.
Measure & Verify: Confirm wall thickness with a ball mic or neck-thickness gauge; consistency is the goal.
Tip: Always lube lightly and clean cases after turning. Uniformity—not aggressive material removal—is the performance driver.
Compatibility & Fit
Tooling: Designed for Hornady neck turning systems.
Caliber: .17 caliber centerfire cartridges (e.g., 17 Remington, 17 Hornet, 17 Fireball, and other .17-cal wildcats).
Note: Confirm exact case neck dimensions and desired final thickness for your chamber. Some chambers prefer light neck turns; others require specific thickness for a snug fit.
Specifications
Product: Hornady 17 Caliber Neck Turning Mandrel
Caliber: .17
Material: Hardened steel
Part Number (MPN): 391908
UPC: 090255919080
Use With: Hornady outside neck turning tool body (sold separately)
Best Practices for Pro Results
Anneal First (Optional): Softer, stress-relieved necks cut smoothly and uniformly.
Measure Before & After: Track thickness with a 0.0001"-reading tool to confirm the cut is even.
Keep It Clean: Deburr and polish lightly after turning; residue can affect seating feel.
Work in Batches: Standardize your brass lot-by-lot to keep seating force and velocities consistent.
Record Settings: Note cutter depth, lube, and brass lot for repeatable workflows.
Frequently Asked Questions
Q: Do I need to neck turn all my .17-cal brass?
A: Not always—many chambers shoot well without it. However, neck turning helps when chasing maximum precision, sorting mixed brass, or fitting brass to tight-neck chambers.
Q: Will this mandrel fit non-Hornady turners?
A: It’s engineered for Hornady neck turning systems. Cross-compatibility depends on the third-party tool’s dimensions—verify before purchase.
Q: How much should I cut?
A: Remove the least amount needed to even wall thickness. Aggressive cuts can shorten case life; the goal is uniformity, not thinness.
Q: Can I use this for expanding necks?
A: This mandrel is designed to support the neck during turning. For neck expansion or sizing, use the appropriate Hornady or die-set mandrels.
SEO Highlights (Naturally Integrated)
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The Bottom Line
If you’re building precision .17-cal loads, the Hornady 17 Caliber Neck Turning Mandrel (391908) is the small tool that makes a big difference—delivering uniform necks, consistent release, and repeatable accuracy you can see on paper and in the field.
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