So, for optimum accuracy and case life, the goal is to set the shoulder back the minimal amount while still enjoying reliable feeding. But if you own several rifles of the same caliber, and you want your reloads to function flawlessly in all your rifles, then you will need to set the shoulder back from the shortest chamber. This way it will cycle in all rifles.

There are a number of options for measuring headspace and shoulder set-back.

1. One of the more common methods, and least expensive, is a collet or bump gauge that fits in a standard set of dial or digital calibers. Hornady and Sinclair are popular and the collets are quite affordable. The most expensive part is an accurate set of calipers, which every conscientious reloader should own.

2. Another option is the RCBC Precision Mic set specific to each common caliber. These are very handy but a little slower than using calipers. Cost is around $50 depending on caliber.

3. The top shelf option is a Cartridge Comparator from Dave Manson Precision Reamers. This system consists of an indicator stand with a base, datum blocks, and plunger-type dial indicator. Once set-up it is very accurate and efficient to use.

These three systems are not only used to measure headspace and shoulder set-back on reloading brass, but they are also to be used when measuring the overall length and seating depth for bullets. For more consistent accuracy from your reloading brass, you will generally want to load your bullets longer and closer to the lands than most factory ammunition. You will often hear shooters talking about 0.015” off the lands or a jump of twenty thou – meaning that the ogive of the bullet is 0.020” back from the lands. However, if you are feeding rounds from the magazine for hunting or competition, then you will be limited to an overall length (OAL) that still fits in the magazine.

Finally, as you get into reloading, and in particular reloading for precision rifle shooting, the more you need to quantify actual measurements and tolerances. Don’t think of this as a painful chore. Instead, treat it as a science that you are attempting to perfect. Once you really understand the advantages of reloading and see the proof on the target, in your scores, and the tight groups, you will find precision reloading to be as enjoyable as the shooting itself (well, almost). There is something very satisfying about producing high quality rifle ammunition

Headspace on Old Military rifles

An old military surplus rifle like a Mauser, Mosin Nagant, '03 Springfield, Enfield, Arisaka, and others may close on a NO-GO gauge. If it does, check it with a FIELD gauge. A FIELD gauge measures the absolute maximum allowable, safe headspace. If the bolt does not close on a FIELD gauge, and the gun is in good condition, it is generally safe to shoot.

However, the strength of these old guns can vary a lot depending on when and where they were manufactured. Headspace is not the only factor in deciding whether one of these guns - or any gun for that matter - is safe to shoot. When in doubt, take it to a qualified gunsmith to have it checked out.