Full Length versus Neck Sizing

By cizentrysite on June 2, 2020
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One of the most frequently heard questions we hear at Creedmoor Sports is,
“Should I neck size or full-length size?” There is no proven right or wrong answer or at least one that has documented statistically valid data backing it up. You’ll often see guys showing results after shooting only 4 or 5 groups. This usually does not present enough data and is not a blind study, meaning the tester can probably tell which is which from bolt closure and can subconsciously influence the results. Regardless, I’ll be glad to give you my thoughts on the matter.

I have personally done both neck sizing and full-length sizing over the past 35 years of shooting and found that some rifles seem to prefer neck sizing only while others seem (non-statistical valid data) to perform better with full length sizing. Key word is seem (again, not statistically valid), I’ve done both types of sizing in tight neck custom chambers and factory chambers. I was taught thinking that neck sizing was the best for accurate shooting and a majority of us used to do this in short range benchrest. Eventually most of us migrated to bumping the shoulder or using a traditional full-length die. I think the question really comes down to the type of situational shooting?

First the differences; with neck sizing dies (whether bushing or conventional) you are only resizing the case neck, and with most setups, not the complete length of the neck. When full length sizing with a properly setup die, you are pushing the shoulder back .002” to .003” ideally (some reloaders shoot for only .001”). Also, you are sizing the case neck and the body of the case.

Let’s chat about the advantages of each.

Neck Sizing Advantages

Neck sizing has two main arguments that some reloaders will make in favor of it.

– The first argument is that the case, having been fireformed, now has a close semi-tight to tight fit in the chamber providing better alignment of the case neck/bullet to the chamber. I believe this argument because the fireformed case should align better in a close-fitting chamber. But, does it materially improve the accuracy, especially when the bullet usually has only .000” to .020” of bullet jump depending on the load tuning?

– The second argument is about case hardening and case life. Neck sizing works the brass less than full length sizing. By neck sizing, you keep from working the body of the case and in some situations may get an extra firing before needing to trim. But eventually you will have to full length size so you can extract the brass without beating on the bolt handle.

Full Length Sizing Advantages

Full Length sizing has one major advantage – easy extraction of the fired brass.

– If you are competing in a sport such as F-Class, service rifle and even benchrest, being able to cycle the brass quickly without disturbing your position or the gun allows you to shoot in the same wind condition. I used to neck size my 6 PPC brass for short range group benchrest shooting and significantly disturbed my rifle position on the rest after a hard bolt lift to extract the brass and then lost several seconds in re-acquiring my aiming point. In a position rifle such as service rifle you could actually disturb your NPA (natural point of aim) due to extraction difficulties.

Any of the precision rifle action-based sports, such as PRS and NRL, would also be negatively impacted by a stiff bolt cycle.

– Rapid fire competitions and hunting are also venues where full-length sizing is critical.

My Humble Opinion

My personal position is that I will full length size my fired brass every time I shoot. I setup my die to push the case shoulder back approximately .002”. I use a bushing style threaded die most of the time. On rifles where I have fully turned necks, I’ll use a specific bushing to obtain the desired bullet grip. On non-neck turned brass or brass where I have turned just enough to clean up thick spots, I’ll use a bushing that sizes all of my brass just enough so that the inside neck dimension is slightly smaller than the diameter of my expander ball. By doing it in this manner, when I pull the brass out of the die and over the expander ball, all of my brass will have approximately the same inside dimension (i.e. bullet grip/tension).

I full length size mainly for the reward of not having to wrestle with my bolt on the line whether in position, shooting F-Class off a bipod or rest or shooting short range benchrest. Any perceived gain in accuracy is just not worth the aggravation or the impact to not running your shots in a condition. If you full length size, you can concentrate more on reading the wind, focusing on position fundamentals and maintaining your natural point of aim.

If you chat with most highly competitive long-range shooters, most of them will feel the same way and these are folks that would go to great lengths for a little bit more accuracy. But they know the impact of losing a wind condition or the impact a distraction of a sticky bolt can make on their performance.

Best wishes and good shooting,

Bill Gravatt