Case neck length

Does a longer case neck help to minimize throat erosion? I've been told that it helps to straighten the flow of the hot extruded powder kernals before they travel down the barrel.

I've been told the same, with steeper shoulder angle and neck length.

That's been the theory for quite some time. A longer throat supposedly also allows for the flame "focal point" to remain in the neck of the case rather than in the throat. A sharper shoulder angle is reported to accomplish a similar effect on a shortish neck length cartridge such as the 243 (going to an AI version).

Not certain any of it has been proven. Ballistics engineers are baffled by a great number of things. Because they happen so rapidly, most of these things are difficult to measure.

cabelasken said:

Does a longer case neck help to minimize throat erosion? I've been told that it helps to straighten the flow of the hot extruded powder kernals before they travel down the barrel.

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Excessive chamber pressure plays a major role in throat erosion. I have wildcats with sharper shoulder angles and shorter necks without issues. Heck, for most .264 WM/7MM RM/300 WM, 7MM STW, etc., have short necks. Here is one to ponder.

cabelasken said:

Does a longer case neck help to minimize throat erosion? I've been told that it helps to straighten the flow of the hot extruded powder kernals before they travel down the barrel.

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The reality is that there is very little confirmation of any facts regarding neck length and throat erosion. We can't crawl into the barrel to observe any action while it may be taking place and we can't confirm that it's not the flame point or heat of explosion from differing powders which causes erosion. Then there are a few other possibilities as well which can contribute to throat erosion. Plus the degree of erosion will have lesser or greater effect on the owner when they choose to accept or reject the amount the might see using a borescope.

As seen below, are examples of both short and long neck length cartridges. You can also include the 7mm WSM which was initially rejected for it's short neck causing us to create a wildcat 7mm-300WSM to have a longer neck. Fussy shooters. Once again though the the 7mm WSM is being received with open arms as a perfectly viable intermediate power cartridge.

The .243 is wildly popular while the longer necked 6mm Remington has seen rejection for very odd reasons. I chose to use a variation of the 6mm Remington named the 6mm Crusader. This case retains the long neck but increases the shoulder angle to 32 degrees. I also reject the criticism of the .243 WSSM and continue to shoot it as a hunting and longer range target cartridge.

Bear in mind that it's been the lack of better designed powder and primers which contributed to those claims of barrel burner. Manufacturers also went to great lengths to deceive us by using lighter bullets and more powder to achieve those startling claims of high velocities which contributed to shorter barrel life.

It's not any one factor but several which will essentially make a difference.


As a caliber, the 6mm has the least number of commercial members. Starting at left is the ill-fated .243 WSSM, .243 Win., 6mm Rem. (originally the .244 Rem.), and .240 Weatherby.

Tiny Tim said:

That's been the theory for quite some time. A longer throat supposedly also allows for the flame "focal point" to remain in the neck of the case rather than in the throat. A sharper shoulder angle is reported to accomplish a similar effect on a shortish neck length cartridge such as the 243 (going to an AI version).

Not certain any of it has been proven. Ballistics engineers are baffled by a great number of things. Because they happen so rapidly, most of these things are difficult to measure.

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Agree, I am looking for the data to prove these things, but finding it difficult.

sable tireur said:

It's not any one factor but several which will essentially make a difference.

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Yup

Neck length is often attributed with having an effect on throat erosion, however, if you experiment with a case design enough, as I have since 2000, it becomes apparent that it is not the length of the neck, but the combination of shoulder angle, neck length percentage over calibre and where the shoulder/body junction is within the powder column.
Keeping neck length at 25% above calibre, allows a transition from shoulder/body datum to shoulder/neck datum where powder gases are held back inside the case, reducing throat erosion from both heat and erosion from powder plugs travelling behind the bullet.
Increasing the neck length has little effect on throat erosion, but using steep shoulder angles of 40°, 45° or even 50° does.

Cheers.