Bushing holder with 4 grub screws

The most accurate way to hold your comparator bushing

The bushing holder keeps your comparator bushing on the jaw of your calipers. This version locks the bushing with grub screws, small set screws that clamp the bushing from the side. That leaves nothing sticking out and lets the holder sit completely flush against the jaw of your calipers, exactly what you want when you measure to the hundredth of a millimetre.

Why the grub screw version

Because the grub screws sit flush, this holder fits tightly and without protruding parts on your calipers. That gives a secure grip on the bushing and a more accurate, more repeatable measurement than a version with a single thumb screw. The trade-off is that you need a small hex wrench to change bushings, so swapping is a touch slower. For anyone after maximum accuracy, this is the better choice.

Use

With your Derraco comparator and the right bushing you measure the ogive length of your bullet (CBTO) and the headspace of your case from the shoulder datum. In exactly those measurements every hundredth counts, and a holder that sits flush and firm on your calipers removes a source of error from your measuring process.

Compatibility

This bushing holder works only with the Derraco Engineering Headspace & Bullet Comparator set. It does not fit the Hornady comparator set.

Specifications

• Type: bushing holder for the Derraco Headspace & Bullet Comparator set

• Fastening: grub screws, flush finish

• Material: 303 stainless steel and brass

• Compatibility: Derraco comparator set only (not the Hornady comparator set)

• Use: holding a comparator bushing for CBTO and headspace measurements

• Manufacturer: Derraco Engineering