Working with Cartridges and Chambers

  • What’s the best factory ammo to reload?  Factory ammo is manufactured in a wide range of quality.  Budget ammo may have components such as aluminum cases that should not be reloaded.  Measure and select only quality components for reloading, realizing that there can be variance in lots and unannounced component changes that optimize the factory’s profits.  Carefully inspect once-fired cases for thin brass, punched primer holes that must be deburred and non-standard primer holes.
  • How can I easily verify that my loads are in spec?  Get a case gage for each caliber you own and know how to use it.  The case gage is a representation of the chamber, and can verify that a cartridge will chamber in a SAAMI spec firearm.  Perform the “Plunk Test” with the case gage by lightly dropping the cartridge into the gage so that it goes “plunk” - and doesn’t stick, protrude, or otherwise be out of spec.  A maximum case gage can be used to verify COAL, diameter, headspace and the ability to chamber in an as spec’d chamber. 
  • How do I measure the chamber in my firearm? Semi-auto chamber tolerance vs. bolt-action rifle or revolver… There are several ways to do this. The best is to measure using the Hornady Comparator Tools pictured in our site. You will be able to measure both headspace and maximum cartridge length (bullet in contact with the rifling). These measurements are CRITIAL for anyone looking to reload any rifle cartridge. 
  • How far from the rifling should I seat bullets in my rifle? How does seating depth affect function vs. accuracy?  With bullet seating, how far is too far? If loading for use in multiple firearms or for a magazine, load to SAAMI specs.  If loading precision ammo for a particular rifle, often the best groups are achieved when the bullet is seated somewhere from .005 off the rifling to .050. Every rifle and bullet combination are unique, so the only want to know is to build and fire different seating depth test groups in your rifle.
  • What is headspace and how can I control it? Headspace is the distance from the face of the locked bolt to the spot in the chamber that prevents the cartridge from moving forward.  This spot is the case mouth for rimless cartridges like the .45 Auto, the Datum Line for most bottleneck cartridges, and the rim for cartridges like the .357 Magnum.  Headspace is critical, as insufficient headspace can prevent the bolt from closing on a chambered round and excessive headspace stresses the cartridge and can cause gasses from firing to leak in unintended places, potentially damaging the firearm or the shooter. Headspace gages are available that are caliber-specific and make measuring headspace easy.  Cases that headspace on the case mouth can present excessive headspace if they are too heavily crimped or are too short.
  • How do I most accurately measure headspace for my firearm?The best is to measure using the Hornady Comparator Tools pictured in our site.
  • What’s the difference between 556 vs. 223?  The 556 was developed as a military chambering, with significant differences in pressure curves, throat/leade, case thickness and internal capacity.  A general rule is that .223 ammunition can safely be fired in a firearm chambered for 556, but 556 ammunition should never be fired in a firearm chambered for .223.  Follow manufacturers recommendations and your loading manual.
  • I’ve heard the 9mm is finicky for reloading – what’s different?  The popular 9mm Luger (a.k.a. 9mm Parabellum) is a high-pressure cartridge with a tapered case.  The sizing die must be adjusted to ... Exact seating. Min/max OAL Seating depth (both min and max COAL) are critical with high pressure cartridges such as 9mm!