The Hornady Shell Holder #37 for Case Trimmer (Hornady part no. 390577T) locks a case by its rim into a Hornady case trimmer, holding it centered and square while the case is cut to length. Made by Hornady, this shell holder is numbered to a specific rim and case-head dimension, so it clamps the brass securely without letting it wobble or spin off-axis during trimming. Handloaders who trim rifle or pistol brass as a routine case-prep step rely on the correct shell holder to get a consistent, square case mouth every time. It’s a small accessory, but the wrong or missing shell holder is one of the most common reasons a trim comes out uneven.

Key Specifications

• Shell holder #37 is the size designation matching this holder’s rim/case-head dimension.
• Built for the Hornady case trimmer to hold brass centered and square during trimming.
• Locks the case by the rim, preventing wobble or off-axis cutting.
• Steel construction holds its grip through repeated trimming sessions.
• Standalone spare part, sold separately from the trimmer body for owners who need a specific number.

Frequently Asked Questions

What does this shell holder do? It clamps a case by its rim inside a Hornady case trimmer so the case stays centered and square while it’s cut to length.

Does one shell holder number fit only one caliber? Shell holder numbers correspond to a rim/case-head diameter, which some calibers share; check Hornady’s shell holder chart to confirm fit for your specific brass.

Buy the Hornady Shell Holder #37 for Case Trimmer

Order the Hornady Shell Holder #37 for Case Trimmer from our Lubbock, Texas gun shop for fast, direct shipping to your reloading bench. Browse our full lineup of reloading accessories for the rest of your case-trimming setup.