Bullet neck depth

[RonR]

This is further to an earlier thread on ogive to base length...with 4 different bullets purposed for fire forming and trigger time. The measurements for each bullet (ogive to base) to provide .020 jump will result in a different amount of bullet depth into the cartridge.

I've read on a few threads that as a general rule of thumb that the bullet depth from the edge of the neck into the cartridge is the bullet diameter. Yodave had an interesting response that in some cases for his loads that bullets weren't seated that far at all, and without knowing the applications I wan't to post to understand more. (No intention at all Yodave to question any of your wisdom, your posts are valuable and have taught me much.)

I would like to hear from those that would share, how shallow or deep they've gone? (reloading terms here )

Secondly, what is the point at which the bullet "lack of depth" become concerning?

Pardon any ignorance on my part but what's anticipated physically if the bullet is seated 1/2 of bullet diameter?


Of note:
- hunting application
- all 4 bullets @ .020 jump, fit in the magazine
- Savage bolt 7mm-08's
- sophomore reloader

Regards
Ron

 

[sure as shootin]

I don't if it's the same for all makes of bullets but the rep from Barnes told me today you want at least 2/3 of caliber or more for the seating depth for their copper pills so just multiply 0.66 times whatever calibre you're loading for,,,,so obviously less than the bullet diameter. A .308 for example, the minimum seating depth would be: 0.66 (2/3) x .308 = 0.203" (that's approx. 1/5 of an inch or 20% of an inch). Maybe it's different for other types of bullets with lead in them. I'm sure there's others with far more knowledge in this area than what I just learned today about mono bullets so likely they'll be able to pass on the goods,,,,maybe for them it's the length of the bullet diameter.

 

[bearhunter]

The reason for long necks on cartridge cases in no longer really necessary. One of the reasons for those long necks was to hold the longer/heavier bullets of the early cartridges under recoil and to aid in accuracy.

We delved into this issue in depth back in the seventies. While on a road trip on my Moto Guzzi I dropped in to PO Ackley's shop in Utah. Fantastic gentleman and very forthcoming/hospitable.

I have an interest in wildcat cartridges and that was right up his alley. He took time off from an extremely busy schedule to explain some of his theories and show me his test facilities. He even gave me lunch.

Anyway it was his theory that long necks were not necessary for good accuracy or to build up proper pressure curves with modern bullets and powders. He also felt that the materials used to make up modern brass were much more ductile and stronger than they were even in the 1930s. This means that with ideal sizing there should be more than enough neck tension to hold the bullets tight and straight under all conditions.

The cartridges that he used for examples were the 308Win and 223Rem. They both have relatively short necks.

I was concerned because of incidents with Kabooms as suffered by the Boers when they purchased a bunch of cartridges with reloaded, short necked cases. They had numerous Kabooms in the field that were blamed on the short necks. His theory was that because the Boers also purchased lighter/shorter bullet which they chambered in their existing rifles, didn't have enough neck length to hold the shorter bullets until they entered the lands and were actually free to do as they wished in the extremely long throats. Who was I to argue?? He purposely tried to cause a Kaboom by making up reamers with grossly long throats to create excessive fee bore and create the ideal condition for a failure. He never succeeded.

His rule of thumb for wildcats was one caliber necks and if the bullets were held tightly without run out or loosening while in the mag during firing they could be seated out as far as practical. One of his favorite cartridges was the 300 Savage. He felt it utilized as much case capacity as possible without straightening the side wall of the case.

When I now go to a wildcat and want something a bit different, if it isn't already available, I have the reamer made up with a one caliber neck. The small difference in case capacity is so minimal there is no noticeable effect on velocity.

The big thing when it comes to accuracy is to find the sweet spot your particular rifle likes to give you acceptable accuracy when the bullet is seated off the lands. I have a habit of seating my bullets so they usually touch the lands just enough so the camming action of the bolt slightly sets the bullet back into the neck. If your chambers are tight this is a safe practice and bench rest shooters do it regularly with similar actions we use for hunting, albeit with tighter tolerances. Some rifles actually shoot better when the bullets are seated off the lands. Rifles like the Tikka T3 don't seem to care one way or another until their throats start to erode.

 

[silver 55]

A couple of good posts on here already.
I am dealing with a new to me rifle and cartridge. Due to a problem with a chamber reamed extra long, I have to seat the bullet with about .100 of contact in the neck. It is a .224 bullet. this is where the accuracy gets interesting. Right now I am working on load development.
All I have to say is ,,,as long as your cartridge will fit in your mag, as long as you can seat a bullet in the chamber and extract it, you should be good to go.
I don't think there is any hard and fast rule about bullet/cartridge contact, if you can make it work for you, should be good to go.

 

[Rod B]

The reason for long necks on cartridge cases in no longer really necessary. One of the reasons for those long necks was to hold the longer/heavier bullets of the early cartridges under recoil and to aid in accuracy.

We delved into this issue in depth back in the seventies. While on a road trip on my Moto Guzzi I dropped in to PO Ackley's shop in Utah. Fantastic gentleman and very forthcoming/hospitable.

I have an interest in wildcat cartridges and that was right up his alley. He took time off from an extremely busy schedule to explain some of his theories and show me his test facilities. He even gave me lunch.

Anyway it was his theory that long necks were not necessary for good accuracy or to build up proper pressure curves with modern bullets and powders. He also felt that the materials used to make up modern brass were much more ductile and stronger than they were even in the 1930s. This means that with ideal sizing there should be more than enough neck tension to hold the bullets tight and straight under all conditions.

The cartridges that he used for examples were the 308Win and 223Rem. They both have relatively short necks.

I was concerned because of incidents with Kabooms as suffered by the Boers when they purchased a bunch of cartridges with reloaded, short necked cases. They had numerous Kabooms in the field that were blamed on the short necks. His theory was that because the Boers also purchased lighter/shorter bullet which they chambered in their existing rifles, didn't have enough neck length to hold the shorter bullets until they entered the lands and were actually free to do as they wished in the extremely long throats. Who was I to argue?? He purposely tried to cause a Kaboom by making up reamers with grossly long throats to create excessive fee bore and create the ideal condition for a failure. He never succeeded.

His rule of thumb for wildcats was one caliber necks and if the bullets were held tightly without run out or loosening while in the mag during firing they could be seated out as far as practical. One of his favorite cartridges was the 300 Savage. He felt it utilized as much case capacity as possible without straightening the side wall of the case.

When I now go to a wildcat and want something a bit different, if it isn't already available, I have the reamer made up with a one caliber neck. The small difference in case capacity is so minimal there is no noticeable effect on velocity.

The big thing when it comes to accuracy is to find the sweet spot your particular rifle likes to give you acceptable accuracy when the bullet is seated off the lands. I have a habit of seating my bullets so they usually touch the lands just enough so the camming action of the bolt slightly sets the bullet back into the neck. If your chambers are tight this is a safe practice and bench rest shooters do it regularly with similar actions we use for hunting, albeit with tighter tolerances. Some rifles actually shoot better when the bullets are seated off the lands. Rifles like the Tikka T3 don't seem to care one way or another until their throats start to erode.

Very informative & interesting.

 

[RonR]

I don't if it's the same for all makes of bullets but the rep from Barnes told me today you want at least 2/3 of caliber or more for the seating depth for their copper pills so just multiply 0.66 times whatever calibre you're loading for,,,,so obviously less than the bullet diameter. A .308 for example, the minimum seating depth would be: 0.66 (2/3) x .308 = 0.203" (that's approx. 1/5 of an inch or 20% of an inch). Maybe it's different for other types of bullets with lead in them. I'm sure there's others with far more knowledge in this area than what I just learned today about mono bullets so likely they'll be able to pass on the goods,,,,maybe for them it's the length of the bullet diameter.

Thanks for the response and the math for clarity. It's neat that you got a chance to speak with the Barnes rep. One day I'll try those.

Regards
Ron

 

[RonR]

The reason for long necks on cartridge cases in no longer really necessary. One of the reasons for those long necks was to hold the longer/heavier bullets of the early cartridges under recoil and to aid in accuracy.

We delved into this issue in depth back in the seventies. While on a road trip on my Moto Guzzi I dropped in to PO Ackley's shop in Utah. Fantastic gentleman and very forthcoming/hospitable.

I have an interest in wildcat cartridges and that was right up his alley. He took time off from an extremely busy schedule to explain some of his theories and show me his test facilities. He even gave me lunch.

Anyway it was his theory that long necks were not necessary for good accuracy or to build up proper pressure curves with modern bullets and powders. He also felt that the materials used to make up modern brass were much more ductile and stronger than they were even in the 1930s. This means that with ideal sizing there should be more than enough neck tension to hold the bullets tight and straight under all conditions.

The cartridges that he used for examples were the 308Win and 223Rem. They both have relatively short necks.

I was concerned because of incidents with Kabooms as suffered by the Boers when they purchased a bunch of cartridges with reloaded, short necked cases. They had numerous Kabooms in the field that were blamed on the short necks. His theory was that because the Boers also purchased lighter/shorter bullet which they chambered in their existing rifles, didn't have enough neck length to hold the shorter bullets until they entered the lands and were actually free to do as they wished in the extremely long throats. Who was I to argue?? He purposely tried to cause a Kaboom by making up reamers with grossly long throats to create excessive fee bore and create the ideal condition for a failure. He never succeeded.

His rule of thumb for wildcats was one caliber necks and if the bullets were held tightly without run out or loosening while in the mag during firing they could be seated out as far as practical. One of his favorite cartridges was the 300 Savage. He felt it utilized as much case capacity as possible without straightening the side wall of the case.

When I now go to a wildcat and want something a bit different, if it isn't already available, I have the reamer made up with a one caliber neck. The small difference in case capacity is so minimal there is no noticeable effect on velocity.

The big thing when it comes to accuracy is to find the sweet spot your particular rifle likes to give you acceptable accuracy when the bullet is seated off the lands. I have a habit of seating my bullets so they usually touch the lands just enough so the camming action of the bolt slightly sets the bullet back into the neck. If your chambers are tight this is a safe practice and bench rest shooters do it regularly with similar actions we use for hunting, albeit with tighter tolerances. Some rifles actually shoot better when the bullets are seated off the lands. Rifles like the Tikka T3 don't seem to care one way or another until their throats start to erode.

That's an amazing story. An explanation like that is something you don't come across everyday. (Truth be told, I tried finding a similar post that you may have put up before but for the life of me I couldn't find it.) This response is really valuable. Thank you.

The sweet spot is what everyone's after, of course, and I want to approach it methodically....but instead of approaching it head on at this point in the season with a defined bullet and powder, I want to circle around a bit and investigate with less expensive bullets and powder to understand a little bit more about my rifle and my son's Savage. Trigger time helps the both of us.

Thanks for your time Bearhunter. Much obliged.

Regards
Ron

 

[yodave]

I just aquired a really long throated 6mm ppc, with 68 grain flat base bullets I am left with about a sixteenth of an inch of the bullet base in the case neck when the bullet makes soft contact with the rifling. During load development earlier in the week I was awarded with a 0.145 5 shot group at 100 yards. I single load this rifle and don't carry my ammo in my jacket pocket so I am just going to go with it.......

long necks stem from way back with the use of lubed cast bullets, the neck was long enough to protect the lube in the lube grooves, since then the lead bullets have been replaced with copper jackets but the necks were never altered.

Where did the original set of OAL lengths come from?? well if you seat a bullet to the book value and then hold another bullet along side you will find the base of the bullet is right at the neck shoulder junction, this for years was thought to be the sweet spot, as bullet shapes and designs emerged on the market nothing about the brass cases or the chambers were altered, so we just made things work, on todays target rifles most of the chambers are spec'd for a particular bullet set at a particular place in the case, does this work with factory chambers? sometimes but not always.

short necks and shallow seated bullets result in run out, hence the old golden rule of 1 diameter of bullet seated in the neck to maintain control on run out, the big question of the day now is this..........is your factory rifle capable of suck high degrees of accuracy to notice the difference? even in the most capable of hands??

 

[RonR]

A couple of good posts on here already.
I am dealing with a new to me rifle and cartridge. Due to a problem with a chamber reamed extra long, I have to seat the bullet with about .100 of contact in the neck. It is a .224 bullet. this is where the accuracy gets interesting. Right now I am working on load development.
All I have to say is ,,,as long as your cartridge will fit in your mag, as long as you can seat a bullet in the chamber and extract it, you should be good to go.
I don't think there is any hard and fast rule about bullet/cartridge contact, if you can make it work for you, should be good to go.

So if I am interpreting this correctly, bullet depth into the neck is less than half of bullet diameter in your case? Interesting situation. Good luck on your load development.

Noted on the hard and fast rule part...just checking in case I'm not missing something on the physics. A lot of wisdom on here. Managed to get one heck of a post by Bearhunter!

Regards
Ron

 

[RonR]

I just aquired a really long throated 6mm ppc, with 68 grain flat base bullets I am left with about a sixteenth of an inch of the bullet base in the case neck when the bullet makes soft contact with the rifling. During load development earlier in the week I was awarded with a 0.145 5 shot group at 100 yards. I single load this rifle and don't carry my ammo in my jacket pocket so I am just going to go with it.......

Incredible.

Where did the original set of OAL lengths come from?? well if you seat a bullet to the book value and then hold another bullet along side you will find the base of the bullet is right at the neck shoulder junction, this for years was thought to be the sweet spot, as bullet shapes and designs emerged on the market nothing about the brass cases or the chambers were altered, so we just made things work,

Interesting. Firearms designs advancing, all based on established common practice/thoughts on basic accepted cartridge design...whoa. Hence so many cartridges and designs ... and now special Nosler cartridges. That's a bit to think about.

short necks and shallow seated bullets result in run out, hence the old golden rule of 1 diameter of bullet seated in the neck to maintain control on run out, the big question of the day now is this..........is your factory rifle capable of suck high degrees of accuracy to notice the difference? even in the most capable of hands??

You are right Yodave...the small piddling around and concerning myself over the finer details may not have a significant effect on the rifles we have. It may be a unicorn in this situation.

Truthfully I was so amazed at the accuracy improvements, with our home rolled, that I've gone down this slippery slope. There will be a point of not getting any better with the rigs we have and we'll look at something more advanced, but have a leg up on making the most of what we have built.

Appreciate your time Yodave.

Regards
Ron

 

[bearhunter]

Incredible.



Interesting. Firearms designs advancing, all based on established common practice/thoughts on basic accepted cartridge design...whoa. Hence so many cartridges and designs ... and now special Nosler cartridges. That's a bit to think about.




You are right Yodave...the small piddling around and concerning myself over the finer details may not have a significant effect on the rifles we have. It may be a unicorn in this situation.

Truthfully I was so amazed at the accuracy improvements, with our home rolled, that I've gone down this slippery slope. There will be a point of not getting any better with the rigs we have and we'll look at something more advanced, but have a leg up on making the most of what we have built.

Appreciate your time Yodave.

Regards
Ron

You are just dipping your toes into the holy grail of extreme accuracy. You will have to be the judge of when and where you are happy.

If you follow the paths of many here, it will mean going onto purpose built rifles that really have no other purpose than punching holes in paper at measured distances with extremely refined handloads and equipment. Can you say lots of money and time??

 

[yodave]

You are just dipping your toes into the holy grail of extreme accuracy. You will have to be the judge of when and where you are happy.

If you follow the paths of many here, it will mean going onto purpose built rifles that really have no other purpose than punching holes in paper at measured distances with extremely refined handloads and equipment. Can you say lots of money and time??

it's not costing you much until your on your third wife............LOL

 

[sure as shootin]

it's not costing you much until your on your third wife.........…LOL

Isn't that supposed to be the definition of stupidity,,,,,doing the same thing over and over again and expecting different results? LOL You'd think most guys who had more than an ounce or two of grey matter between the ears would have it all figured out after the end of the second marriage. Haha.

 

[yodave]

Isn't that supposed to be the definition of stupidity,,,,,doing the same thing over and over again and expecting different results? LOL You'd think most guys who had more than an ounce or two of grey matter between the ears would have it all figured out after the end of the second marriage. Haha.

one would think, but even Douglas will vouch for me that guns and ammo can be hard on a marriage, or 2, possibly even 3

 

[silver 55]

So if I am interpreting this correctly, bullet depth into the neck is less than half of bullet diameter in your case? Interesting situation. Good luck on your load development.

Noted on the hard and fast rule part...just checking in case I'm not missing something on the physics. A lot of wisdom on here. Managed to get one heck of a post by Bearhunter!

Regards
Ron

That is correct, bullet depth is less than half the bullet diameter. The bullet is a rimmed cartridge, 218 Bee. All I have is Winchester brass. The rim thickness averages .055 but my books give me a spec of .065 thickness. I don't know of any one but Winchester making 218 brass and the idea of reforming 32/20 brass is daunting. When I use a cartridge length of 1.880 I get a group of about 3/4" but if I use a cartridge length of 1.995 and jam the bullet into the rifling, I will get 3 rounds into a 1/4" and the other 2 about an 1" or 1 1/2" lower. I believe with the 1.880 rounds I am not getting proper headspace. If I can get this brass to start headspacing on the shoulder, maybe I can make it work. If not, I will have to learn to neck down brass.

 

[Ganderite]

RonR If I had a 7-08 and was loading it for hunting, here is what I would do.

I have had a bullet come out of a case and dump powder in the action before. Several times. Each time the rifle was out of action until I could clean it out. I took it out of stock, washed it under hot water tap, then sprayed with bake cleaner, then re-lubed. Can't do that in the field, when you need the rifle for the first or second shot.

So, given that experience, I would rank reliability ahead of accuracy. So how important is 20 though over 40 thou? have you tested both for accuracy and decided it just has to be 20 thou?

I like the one caliber seating depth idea. But I would not hesitate to go shallower.

But, because of my bad experiences with bullets popping loose, I would do two things. I would use a Lee factory Crimper to add a little crimp. And I would increase neck tension. T do that, I would re-size my decapped brass with the expander button removed. This would give max neck tension.

 

[p-17]

RonR If I had a 7-08 and was loading it for hunting, here is what I would do.

I have had a bullet come out of a case and dump powder in the action before. Several times. Each time the rifle was out of action until I could clean it out. I took it out of stock, washed it under hot water tap, then sprayed with bake cleaner, then re-lubed. Can't do that in the field, when you need the rifle for the first or second shot.

So, given that experience, I would rank reliability ahead of accuracy. So how important is 20 though over 40 thou? have you tested both for accuracy and decided it just has to be 20 thou?

I like the one caliber seating depth idea. But I would not hesitate to go shallower.

But, because of my bad experiences with bullets popping loose, I would do two things. I would use a Lee factory Crimper to add a little crimp. And I would increase neck tension. T do that, I would re-size my decapped brass with the expander button removed. This would give max neck tension.

I agree completely with Ganderite. For a HUNTING application and a hunting rifle, I would not worry about any of this extreme accuracy/benchrest stuff. I would simply find an optimum charge weight and seating depth, using 10-20 thou jump as the starting point and seating deeper until about 100 thou jump. Somewhere in there you will find a load that gives you close to the maximum accuracy potential of the load and rifle, and that is what you should use.

This is assuming that your seating depth node gives you enough support for the bullet. Some of the super modern boattail designs can be a pain because they have a short bearing surface, and it can be a challenge to get enough of it held by the neck and maintain an appropriate OAL. This is why tried and true hunting designs are often better for hunting rifles, especially flat base designs. But the Barnes Triple Shock has a very long bearing surface and it also likes a bit of jump, so it is a very practical choice for building safe, functional and accurate hunting loads. In any case, I always do as Ganderite mentions and size my necks down a little tighter, just to give the maximum amount of hold on the bullet.

I've experienced what Ganderite talks about (opening action and spilling powder into the mechanism because of seating too deep). This happened during an international match, and I lost because my rifle was gummed up. Imagine if this happens in a hunting situation, or when facing down an angry bear?

I have started using the Dan Newberry process and find it to be simple, systematic and useful. The normal practice is that you play with seating depth AFTER you have found the optimum charge weight.

I applaud you for pursuing accuracy to the highest degree. However, if this is something that really interests you, then I would get or build an accurate range rifle, something with a heavy barrel, tight custom chamber, trued action, etc. With such a rifle, the fancy accuracy reloading techniques can make a difference and you won't generally need to rely upon it to stop a charging bear, so you can experiment with things like long seating depth, minimal sizing, blown-out taper, etc.

For a hunting rifle, you want to keep it simple, consistent, reliable and functional under all conditions. This often means compromising a bit on peak accuracy and velocity, but most people get a hunting rifle for HUNTING, not shooting tiny groups on paper.

 

[Gunneegoogoo]

Don't overthink it Ron. If you're crashing through the woods looking for moose, or in the desert looking for cowardly extremists, make sure the bullet is good and firm in the neck either with more contact area, or a tighter neck tension. If you're at the bench shotting singles, trying to shoot 0.145" groups (Dave, that's amazing!!!), then as long as the bullet stays in place, you're golden.

-J.

 

[Ganderite]

Could you have gunsmith set the barrel back one thread and re-chamber?

Or see how it likes 160 gr round nose bullets? That would be my first experiment.

 

[RonR]

You are just dipping your toes into the holy grail of extreme accuracy. You will have to be the judge of when and where you are happy. ??

Thanks for that. You understand where I am at exactly.

If you follow the paths of many here, it will mean going onto purpose built rifles that really have no other purpose than punching holes in paper at measured distances with extremely refined handloads and equipment. Can you say lots of money and time??

I am foreshadowing that...

Thanks for your post!

Ron