The Lock-N-Load® Headspace Comparator extends brass life, improves accuracy, and enhances safety. The gauge measures variations in brass before and after firing or re-sizing. It allows for headspace comparison between fire-formed brass and re-sized brass.
The five bushings that come with the Lock-N-Load® Headspace Comparator provide the ability to check most bottleneck cases, from .17 Rem through belted magnums. Ackley Improved chambers use the same bushing size as the parent case. See chart provided or consult product instructions for cartridge/bushing size details.
Typically, when full-length resizing, the die should be adjusted to set the shoulder back .001" to .002". This will provide a proper (minimal) clearance with the firearm’s chamber. A proper headspace will minimize case stretching, reduce work hardening, extend case life, improve accuracy, and increase safety. Proper headspace also provides proper firing pin contact with the primer to improve the reliability of your loads. For the shooter with an autoloader, check your fired cases by rotating the brass In the Headspace Comparator to identify cases with bent rims – a certain cause of “flyers”.
See chart provided or consult product instructions for cartridge/bushing size details.
Determining the proper bushing diameter: If you add the neck diameter and the shoulder diameter and divide that number by two, use the bushing closest to that number.
Hornady Headspace Bushing Size Chart:
| .17 Rem, 204 Ruger, 221 Rem FB, 222 Rem, 222 Rem Mag, 223Rem, 220 Swift |
| 22PPC, 22/250 Rem, 6PPC, 6BR Rem, 250 Savage, 7BR Rem |
| 6mm Rem, 257 Rob, 25/06 Rem, 270 Win, 7x57mm Mauser, 280 Rem,30/30 Win 30/06 Sprg, 300 H&H Mag, 7.62x39 Brit, 6.5x55 Mauser,7mm WSM, 303 Brit, 30-40 Krag |
| 223 WSSM, 243 Win, 243 WSSM, 260 Rem, 270 WSM, 7mm/08 Rem,
300 Savage, 308 Win, 35 Rem |
| 6.5x284, 284 Win, 7mm Rem Mag, 7mm Ultra Mag, 300 WSM, 300 Wby Mag,
325 WSM, 338 Win Mag, 350 Rem Mag, 375 H&H Mag, 264 Win Mag,
7mm SAUM, 7mm STW, 300 RSAUM, 300 Win Mag, 300 Ultra Mag,
8mm Rem Mag, 338 Ultra Mag, 35 Whelen |
