Truth to longer necks improving barrel life?


Well-Known Member
Mar 25, 2019
So guys, impressed with what the 220 Jaybird COULD have been, I had a question. I'm considering getting a custom reamer for a caliber I want to build, but does anyone actually have and hard evidence (will take some anecdotal) that longer case necks improve barrel life, if so, where do I find such publications or articles?
Thanks. Very curious.
Your gonna find alot of opinions on this and there like a$$holes everybody's got one. LOL
I think there's alot of other things that contribute to barrel life than how long a neck is.
Your gonna find alot of opinions on this and there like a$$holes everybody's got one. LOL
I think there's alot of other things that contribute to barrel life than how long a neck is.
Agreed! There are few here that will also claim longer neck as better design and better accuracy.

Short neck.jpg
Throat erosion is caused by unburnt powder abrading the throat on it's way down the barrel.
The length of the neck may reduce the amount of unburnt powder reaching the throat, but I believe it would be unmeasurable and would not improve the barrel life when other things like pressure, temperature and velocity have the most impact on this problem.

In theory, It may sound possible but like many other things It would be almost impossible to prove. The military believes that the use of ball powder has the most effect on barrel life and throat erosion and when used this will improve. There is a better chance of them being right because I have shot range rifles with over 70,000 rounds through them that shot well. They also believe that 3,000 ft/sec or slower helps. I can vouch for well maintained and properly loaded for rifles, without excessive pressures and temperatures, barrel wear does improve

Just my opinion

The key aspect to getting the longest barrel life possible is keeping the bore cool. I have been building monster, fire breathing wildcats for customers for two decades now and there are a few things i have learned.

1. the throat needs to be designed properly. No larger then 1/2 thou over nominal bullet diameter. The tighter the better. This limits hot gas blow. Hot gas blow by greatly accelerates heat cracking in the bore just ahead of the throat.

2. Its best to seat the bullet within 10 thou of the lands. This allows the bullet to SEAL the bore quickly, not allowing the hot gas blow by.

3. Neck diameter in the chamber matched up with proper neck diameter of the loaded ammo can also greatly effect gas blowby. Loose necks allow significant blow by, accelerating heat cracking.

4. Perhaps most critical, as correctly mentioned, powder burning in the bore causes the most heat build up. The hotter the bore surface, the less able the barrel steel can stand up to heat cracking and erosion. As such, and this is something i preach to my customers, never shoot more then three shot strings. Looking at a three shot string and what it does to the barrel, shot number 1 does very little if any damage to the bore. Shot two also does little damage. Shot three will do as much damage as shots 1 and 2 combined. if you shoot a fourth round, that shot will do as much damage as all three previous shots and if a 5th shot is taken, that 5th shot will do twice as much damage as the first three.

now this is referring my wildcats not a 6.5 creedmore but it does hold true to some degree.

with large hunting cartridges i cringe when i hear people say "if your not shooting 5 shot groups it means nothing"......

i tell my customers, get your rifle zeroed and get off paper. Then work on your drop chart by doing Practical Field Shooting. That being shooting at random measured ranges, setting up each shot like you would in a hunting situation, taking a single shot, recording the impact location and then letting the barrel cool and doing it again at a different range. Targets can simply be small rocks, nothing fancy is needed, just need to be able to clearly see impacts.

in 10 shots you will get more practical practice then 100 shots fired on paper and your bore will never get hot.

with rounds like my 7mm Allen Mag, you can get easily a decade of fine long range accuracy by using the rifle properly, or you can change your barrel every year if used incorrectly.

in my opinion, neck length means nothing to accuracy life..... but again, i am not referring to small rounds.....😉
What follows is, as far as I'm concerned, merely lore though I've seen the predictions of this little bit of wisdom to be true. I just cannot assert that it is in fact true. Perhaps someone with advanced education in the area can opine on that:

From what I've always been given to understand, it's not just length. The shoulder angle plays a part there and affects how long the neck "should" be. If you draw a line extending parallel with the shoulder from the shoulder of each side through where the neck would be and note where the lines intersect, you're seeing where the plasma jet of burning gunpowder is going to cone out and get most intense. So, a .243win with a lopey 20deg shoulder puts the intersection outside the case neck while a .243AI puts the intersection inside the case neck. The difference betwen the two is the .243AI has a sharper shoulder which allows a shorter neck. My testing on this has not been exceedingly scientific but, I've burned the heck out of the throat of a .243win barrel in 1000 rounds. My last .243AI went 80% longer than that and I shot it faster and loaded it hotter.

It makes sense logically but fluid dynamics are usually non-intuitive at best so what seems like logic doesn't always work and why I consider the above to be useful lore.
Over the many decades, there have been various experiments and tests on neck length and throat wear, and many of those old articles are available online, some not. There are many factors that contribute to throat wear, and while the pressure turbulence point is one consideration related to the neck length, it is not the most important factor. This was one of the factors often cited in why the 243W seemed to erode throats faster than the 6mmRem. However, changing the shoulder of the 243W to the AI 40 degree saw increased throat life, for it did change the pressure turbulence point.

Many engineers and advanced loaders/wildcatters, myself included, have experimented with keeping the turbulence point inside the case neck with the idea it would reduce throat erosion via keeping the majority of it inside the brass neck. Limited to some success.

Advance a few decades, and today we have much better powders and barrel steels that are more erosion resistant, but pressure produces heat, and that is the main cause of throat wear. Modern smokeless powders can produce throat flame temps of 4,500-5,000 F with some running a little cooler. Heat cracking then flaking is the main cause of erosion in steel barrels, and over the decades, the shooting world has played with numerous ways to reduce this: Chroming, nitriding, ceramics, TiN, carbonizing, deep freezing, etc, etc. Some work fairly well, others more of a gimmick.

Basically, a barrel is like a set of tires, you can have the 70-80k mile family car versions, or you can have the high performance drag race ones that will perform but not last too long. They are expendable items in the sport. If you want the latest ultra-fast flame thrower and powder Godzilla, there is a price for that. YMMV
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I look at it slightly different,
the powder used can cause extreme erosion, especially Reloader powders, and the ratio of bore to speed of powder
Small bore burning slow powders, like a 243
large bore burning fast powders 308
We've all heard how a 243 only gets 1000 rounds but the 308 5000 rounds
Fiftydriver: Thanks for your suggestions RE: hunting rifles. What do you recommend for Varmint rifles shooting high volume in 20-6mm calibers?

In my high speed chase for never-ending barrel life, I have managed as much as 50% gains over what the Excel based calculator we've all used said it would be with a combination of HBN coating, polygonal rifling and selecting a chambering that puts the turbulence point well inside the neck. That's the difference between a barrel lasting all season and shooting the last match or two with a shotgun.
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