Incipient case head separation due to repeated over-sizing.

How Much Should I Size Cases

Full length sizing - image Forster
Full length sizing – image Forster

Q: I’m puzzled about how much a rifle case should be sized when reloading? I’ve always adjusted the die down to touch the shellholder, and the cartridges feed smoothly though my rifle. But the guy in my local gunshop says this can cause problems. He says a “crush” fit is more nearly ideal, because there is no slop in the chamber and reloads will shoot better and the cases last longer. He advised against screwing the sizing die down until it contacts the shellholder unless it is necessary to get the round the chamber. I don’t have any problems with case life as it is, but which is the right way to go about resizing?
Harold Angwin

A: You both make a point, but more importantly you should understand the reasoning behind one method or the other. Most times, screwing the sizing die down to touch the shellholder brings the round back pretty close to factory dimensions. As a rule they will generally feed and chamber easily. However, if you strike problems with case head separations or cracks just forward of the case web, you’re setting the shoulder back too far with each sizing. This means you should back off a little.

Incipient case head separation due to repeated over-sizing.
Incipient case head separation due to repeated over-sizing.

While it’s true that a “crush” fit will eliminate excessive headspace and prolong case life, it can be a problem if it’s overdone. Occasionally, a case won’t quite be a “crush” fit and may not chamber at all. I suggest you adjust the sizing die to touch the shellholder and then back it off just enough so that your reloads chamber with a slight “feel” as the bolt handle turns down. When reloading for hunting I prefer to use new or near-new brass and full length resize so that the rounds chamber smoothly. I don’t want to risk blowing a chance at a real trophy animal because a reload was too tight or got stuck in the chamber.




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Nick Harvey

The late Nick Harvey (1931-2024) was one of the world's most experienced and knowledgeable gun writers, a true legend of the business. He wrote about firearms and hunting for about 70 years, published many books and uncounted articles, and travelled the world to hunt and shoot. His reloading manuals are highly sought after, and his knowledge of the subject was unmatched. He was Sporting Shooter's Technical Editor for almost 50 years. His work lives on here as part of his legacy to us all.