I have heard many people say that 1 caliber length of the bullet shank needs to be in the case neck for proper tension.

I was told by a wildcat designer that 9/10 of a caliber length of the bullet shank needs to be in the case neck for proper tension.

Today I had a call with Barnes and the said .67 of a caliber length of the bullet shank needs to be in the case neck for proper tension.

What have you all heard or do you practice any of these "rules"?

BTW, I know it has to fit in the magazine and the chamber and I know about distance from the lands for accuracy. I am simply asking this as an isolated question related to minimum amount of bullet shank in the neck.

Not trying to be funny , Mike, but I'm not sure what PROPER Neck TENSION is. Length of bullet insertion is only one determining factor, however( brass hardness , bullet jacket malleability, surfaces roughness and probably a few more ).
When designing my wildcats the shortest necks are 1 Caliber long and the longest were 1.75 calibers long. Didn't do this so much for retention but for concentricity . roger

I start with one caliber deep.

Mike,
I loaded some 5.56 with Berger 80.5's that engaged about .150". I got lower than expected velocities. Since my match was canceled by Irene I have a chance to do a little more work with it. If it's any help I was told to take the base of the shank above the boat tail to the base of the neck. The neck is .205 ish so you can't get a full caliber of grip.

Interestingly enough, .149 is 67% of caliber for 5.56.

"proper neck tension" is probably the wrong phrase...how about consistent pressure, good burn, proper launch into the bore or whatever else you like...

Bottle neck Cartridges.-The base of the bullet (full diameter) when at the neck shoulder junction is best. But COL should be within SAAMI measurements. They do list maximum & minimum COL. Barns wants the bullet to be .050" off the lands to start. Berger has said its OK to jump there VLD bullets to the lands & may be better than a jam. I know the correct COL when i see it.

I designed my first couple wildcats with 1 caliber. As I necked those up I ended up with shorter necks. I never had an issue. If it holds the bullet firmly I live with it.

I think the most definitive answer is "it depends".
A target cartridge that is loaded and then carefully put in a case and gently loaded one by one can get by with a lot less bullet in the neck than can a hunting cartridge that is banged around in a magazine and then racked roughly into battery.
The one calibre rule has been around for as long as I can remember --300Savage and 300WM being notable exceptions-- but I have personally had exceptions that worked very well. I think as long as you get enough bullet in the neck to hold it steady, you're good to go. This would be another vote for using flat based bullets.

The only time I have run into this is with a M700 I have in -06 that has a long throat and long mag and am using light bullets. In order to seat the bullets close to the lands I have run loads with about 1/2 cal contact with no issues. They still stayed straight, gave sub MOA accuracy and never had one fall out

my first question is whether it will fit into the magazine or not

Congrats to Ramrod, wasbeeman, and Blacktailer...see rule No 1

quote:

Congrats to Ramrod, wasbeeman, and Blacktailer...see rule No 1

Excuse me for wasting my time answering. Yes I had always heard "1 CALIBER". So I built my first wildcats using that rule. As I built others with shorter necks I had no issue. So Now I only worry about having enough tension to hold the bullet. So that is the only rule I now follow.

Go any place you want for dinner.

Paul,

You missed understood my post. My post was a compliment. The rules are obviously sarcastic and you first answer was a reasonable answer (as was BT's and wasbeeman's).

You basically said - hey I started with 1, I have used less, and now I really don't worry about it as long as it holds firmly; i.e., 2/3, 3/4 probably are all fine.

i pretty much ignore the "one caliber" alledged rule...

one caliber of .223 is how much surface area?

and 1/2 caliber of .510 is how much?

i do know the square cubed law..

if you can crimp on the groove, the neck length is pretty much irrelevent.

i'll be at my desktop pc tomorrow evening, i think, which has my quickload installed

quote:

Paul,

You missed understood my post.

You are correct I guess I missed it completely.

Guess my skin was also overly thin tonight.

Sorry.

FWIW...I tested neck length "grip" in a 30-06 once...had no trouble with the bullet staying put to slightly less than 1/2 cal...~0.130". Bullet didn't move with recoil or banging against the magazine.

Only tested one round on the bottom of the stack through 10 firings. No difference in the groups, velocity, etc. I only fired 100 in 10 shoot groups, trimmed 0.025 each time, used 5 cases plus one for the control round. Used R-P brass

I think it depends on the caliber also. I seat some of my 17 to 22 cals fairly close to 1/2 cal depending on where the best accuracy is...some of my benchresters in the "olden days" were seated that way and had only the neck spring back to hold the bullet.

My large calibers get whatever the length of the case neck is.

I agree with the "it depends" scenario...it depends on the application and use.

Tell me Jeffe...what is the "square cube law"? That's a new one for me.... Hahahahahahah...

Luck

The only time I worry about neck tension is when I have to pull a bullet, and dont size the case again. Usually I use such loads for practice, loaded one at a time. Another obvious time is on heavy recoil cartridges, and the only one that it's an issue with is my 458, and I use a lee crimp on that one. The 458 is the only cartridge that I load and crimp. Many of my seating dies for the others don't even have the ability to crimp. I've been using Forster dies a lot.

I think neck tension for practically any normal cartridge is a non-issue, except for the situation such as really soft annealing of the necks, or reamed too thin in the neck, of there is something wrong with the die expander button. I've seen the latter on Lee dies more than once.

I've not yet been able to apply the same "rule" to the variety of cartridges and combos that I load, regarding the amount of the bullet that's in the neck and beyond. I do sorta look at the possibility of seating with the base of the bullet even with the bottom of the neck, but it seldom works out to be the best.

More often than not, I seat to the cannelure, and have not been able to prove with any particular rifle, except one, that a different seating depth gives better accuracy. Maybe I havent experimented enough, because I'm still sure it can make a difference. I have proven to myself that a deeply seated bullet in some rifles shoots much more accurately that a bullet seated out nearer the lands. That was on more than one CIP chamber and throat.

In some rifles it just wont work to seat the bullets out, so whatever is below the base of the neck just has to be. The obvious cartridge is a 300WM, and my 338, 30-06, 308 and others simply will not allow it because of magazine length and lands engagment, but they shoot so accurately with the deeply seated bullets (normal seating and OAL) that nothing could be measurably gained by seating differently.

I tried seating the bullets out in 6.5x55, 7x57, 8x57, 9.3x57, 9.3x62, and others with CIP throats, and magazines with plenty of space. The only cartridge that showed accuracy improvment that appeared to be real was the 9.3x57, so I load the bullets even with the base of the neck for that one, partially to give max case capacity for the powder. All the others shoot so accurately with normal seating depth, that I just don't worry about it.

On the wildcat that I'm working with, I had the reamer made so that there is little room in front of the bullet when seated to a cannelure. In the selection of bullets that I may want to use there were none without a cannelure. I loaded some dummy rounds with the bullets seated to the crimp groove, and let the reamer maker take some measurments and cut the reamer accordingly. The cartridge is a belted mag, so when the chamber is cut, it turns out like the reamer maker planed it. That strategy worked out well one time, and I've yet to test the second one that I had done the same way. I already know the seating depth when I get the rifle back - no surprises. Sure, there is slight variation from brand to brand of bullets in the length of the ogive, and thus the distance to the lands, but it hasn't yet proven to be an issue in accuracy, or in any other way.

KB

Minimum seating depth is what ever is needed to keep the bullets from falling out.

The "one caliber deep" thing applied to black powder cartridges. A lot of smokeless cartridge necks are shorter than one caliber.

We tend to make something out of nothing these days..I normally start with one caliber depth on a hunting rifle as ammo can take a beating on Safari etc. and I have seen too many bullets stick in the lands and create a problem when loaded rounds were extracted spilling powder in the action and so fourth..

But in reality bullets have to be seated to fin into the magazines of todays guns unless your a custom rifle person, in which case you know your chamber specs and magazine length so you go from there. I used to do this, but from a hunting standpoint, its really an exercise in futility unless you just enjoy the game, in which case knock your lights out!

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Originally posted by 243winxb:
Bottle neck Cartridges.-The base of the bullet (full diameter) when at the neck shoulder junction is best. ]

For most situations that is what I shoot for anymore. For me, the K.I.S.S. rule applies here.. With very few exceptions the tests Ive conducted reguarding seating depth have produced little to no gains in accuracy. I think manufacturing standards are much closer today and not as many "deep throated" bbls as there used to be may have some bearing. The two things I do NOT want to do are, a) rob myself of case capacity, or B) not seat it in deeply enough..

I think about 3/4 of the caliber is adequate for most applications though.