Understanding Headspace  . . . . the rest of the story

      The term headspace actually means the "space" between the "head" of your case and the breech.   This space needs to be kept to a minimum to prevent a cartridge from moving forward when it gets pounded by the firing pin.   Factory belted loads are designed to have the belt stop any forward movement of the case, but you should always headspace your handloads on the shoulder.   For a better understanding, headspace simply means the clearance between the shoulder of your handloads and the shoulder of your chamber.

      The picture at the left shows where to measure headspace when comparing your handloads to a fireformed case.   This length needs to be resized just short enough to ensure a reliable fit in your chamber.   It also needs to be long enough to prevent the brass from stretching when it is fired.   If there is too much headspace, cases can stretch far enough to crack at the expansion ring.   These cracks are a sign of serious (sometimes dangerous) headspace problems.   During firing, cases expand tightly against the chamber wall.   This seals the high chamber pressure during firing and prevents hot gas from blowing back through the action.   If a case ruptures it could be a safety hazard for the shooter.

      The enlarged picture at the right shows a cutaway view of a belted magnum case that has been reloaded with excessive headspace.   You can see inside the case, where it has been stretched to the point that it is now very thin.   The arrows show where the case stretching is the worst - at the expansion ring.   If a case is going to crack from a headspace problem, this is where it will occur.   Cases with this much wear should be discarded, because they are likely to crack or even rupture on the next firing.   You should always examine this area inside your cases before reloading.   Some handloaders use a sharpened spring hook or even a paperclip to reach in and "feel" the amount of wear in this area.

      Headspace problems are much more common with belted magnum calibers.   This is because ammunition manufacturers always make their belted magnum loads to headspace on the belt.   They also leave the shoulder extremely far from contacting the chamber.   This causes the first firing of belted cases to stretch quite badly.   Your "once fired" case is now stretched considerably, and it is weakened at the expansion ring.   The good news is that further case damage can be kept to a minimum when handloading belted magnums by setting headspace on the shoulder, just as you would for any rimless caliber.   Our Belted Magnum Collet Resizing Die also avoids thinning the brass by ONLY resizing the case inward, and then only when it's needed.

      The only cases that ever actually required a belt are the .300 H&H Magnum and the .375 H&H Magnum.   Because of their unusual shallow shoulder angle, these two calibers actually need to be headspaced on the belt.   In fact . . . . if these 2 calibers weren't such incredible performers (in the early days) there wouldn't be ANY magnum calibers using a belt today.   As you can see on the cutaway case, the belt is located around the "solid" portion of the case, and it obviously adds no strength to the case whatsoever.   The belt was added to over 20 different calibers purely for marketing reasons.   Firearm manufacturers figured that if a new magnum caliber didn't have a belt, like the H&H cases, it would never sell.

      Most shooters that reload belted magnums are familiar with case expansion problems that occur "just above" the belt.   This usually happens after just 2 or 3 firings - wasting perfectly good cases.   Many shooters first discover that their cases aren't getting resized far enough when their handloads begin to stick or even fail to chamber.   Their first thought is that these cases must have a headspace problem.   They assume that their cases are too long . . . . but it's easy to prove that it's really a case "width" problem at the expansion ring.   This problem is now very easy to resolve with a unique new resizing die.

      In order to resize the wall on most fired cases, your resizing die needs to firmly contact the case, and then forcibly squeeze downward almost .100" beyond that point.   This is required just to reduce .001" from the diameter of a tapered case.   The belt on a belted magnum case prevents any conventional resizing die from traveling far enough down the case.   Then as the case is withdrawn, the brass also "springs back" slightly.   That's why I invented the Belted Magnum Collet Resizing Die - to ensure a reliable, perfect fit in your chamber and to extend the life of your cases.   You can read the whole story about this collet die by visiting the lower half of our homepage.