neck tension

[BoydAllen]

I think that the best way to test for that would be to load up some identical loads, with some loaded a day before they were shot, and the rest a month before. Then they could be shot alternately on two targets, over a chronograph, with flags. Some time back, I read a post that indicated that ammo might actually become more uniform with some delay between loading and shooting. The down side to this would be the problem of trying to anticipate conditions so as to be in tune.

 

[nmkid]

LH
Negatory on the stainless pins - I use corncob in a vibrator bowl. The difference in measurements may be the fact that I don't use the sizing plug. To me it makes no sense to squeeze the brass way down then swell it back out. If you check a case out of the die without the sizing plug, I'll bet our numbers will be closer.
GSTAY
No, I don't have a chrono so I really don't know, but it stands to reason that if the "group" dropped an inch it must be due to lower MV. The question is, why would a looser fit on the bullet cause this? It looks as though the reverse would be true.
tommyt

I just recently had an interesting, costly experience by removing the stem from my die. Maybe not the same thing but, I was resizing 6.5-284 to 6-284. I, "thought" I had read that this would help in the resizing. The result...Disaster! The necks got so scrunched(?) that I needed extreme force to use the expander mandrel. It took a long time but I was able to run them all (100) through. I had necks that were visibly longer on one side. I loaded up some dummy cases and I could see the bullets wobbling on the concentricity gauge. Looong story short...Lapua cases ruined by removing the stem! Never again.

 

[DocDoc]

Boyd, a possible solution is to load and seat long. Then reseat to the desired CTO the day before the shoot.

 

[BoydAllen]

Yes that would, and does work. What I was addressing was the idea that if one loaded ones ammo over the course of a couple of days, and then aged it for a month, that there is the possibility that bullet pull might become more uniform within that lot of ammo. I am going from slim anecdotal information here, which is why I suggested a test.

 

[Brians356]

I just recently had an interesting, costly experience by removing the stem from my die.... I was resizing 6.5-284 to 6-284. I, "thought" I had read that this would help in the resizing. The result...Disaster! The necks got so scrunched(?) that I needed extreme force to use the expander mandrel. It took a long time but I was able to run them all (100) through. I had necks that were visibly longer on one side. I loaded up some dummy cases and I could see the bullets wobbling on the concentricity gauge. Looong story short...Lapua cases ruined by removing the stem! Never again.

That's curious, or maybe I missed something (wouldn't be the first time).

So you're saying using the die's expander button works fine, but expanding later using an expander mandrel doesn't?

How long (minutes, hours, days ...) after sizing did you apply the expander mandrel?

Were they brand new Lapua cases?

How consistent were the neck walls in thickness? (I know it's Lapua, but as Reagan said "Trust, but verify.")

How thick were the neck walls before and after "scrunching"?

 

[fguffey]

So you're saying using the die's expander button works fine, but expanding later using an expander mandrel doesn't?

In the perfect world the expander plug does not touch the neck when the ram is raised. The neck is sized when the ram is at the top. The sizer pkug is pulled through the neck when the ram is lowered. There was a time when the sizer plug was not designed to neck a case up. RCBS has a cut-off date meaning dies made after a certain date could be used to neck a case up when forming.

F. Guffey

 

[Dusty Stevens]

What about the bullets sticking more over time? I know ive pulled bullets loaded for say a year and theyre stuck big time

 

['Freak]

LH
Negatory on the stainless pins - I use corncob in a vibrator bowl. The difference in measurements may be the fact that I don't use the sizing plug. To me it makes no sense to squeeze the brass way down then swell it back out. If you check a case out of the die without the sizing plug, I'll bet our numbers will be closer.
GSTAY
No, I don't have a chrono so I really don't know, but it stands to reason that if the "group" dropped an inch it must be due to lower MV. The question is, why would a looser fit on the bullet cause this? It looks as though the reverse would be true.
tommyt

I just recently had an interesting, costly experience by removing the stem from my die. Maybe not the same thing but, I was resizing 6.5-284 to 6-284. I, "thought" I had read that this would help in the resizing. The result...Disaster! The necks got so scrunched(?) that I needed extreme force to use the expander mandrel. It took a long time but I was able to run them all (100) through. I had necks that were visibly longer on one side. I loaded up some dummy cases and I could see the bullets wobbling on the concentricity gauge. Looong story short...Lapua cases ruined by removing the stem! Never again.

How much a fixed diameter sizing die acting on the outside diameter of the neck is going to reduce the inside diameter of the neck is dependent on the neck’s wall thickness. If by whatever means the case neck wall thickness is always going to be the same then the size die could be honed to increase slightly its ID so that by acting on the neck’s OD the die will squish down the neck’s ID so that it’s only a thousandth or so less than the outside diameter of the die’s expander ball or the OD of a separate expander mandrel.

'Freak

 

[fguffey]

What about the bullets sticking more over time? I know ive pulled bullets loaded for say a year and theyre stuck big time

What about? When the neck's ability to hold the bullet is measured in tensions, 'I do not know'. In the last year I have pulled down 450+ magnum rounds without a stuck bullet. Even if I wanted to measure neck tension I would be out of luck, I do not have a gage that measures in tension.

I can measure bullet hold in pounds, I am the only fan of getting all the bullet hold I can get, I can measure bullet hold in pounds when seating a bullet and I can measure bullet hold in in pounds when pulling a bullet.

And now there is a tool designed to measure bullet hold in pounds when seating, and there is no chart for converting pounds to tensions.

F. Guffey

 

[fguffey]

The 450 rounds of magnum ammo I pulled down was loaded in 1970 and 1972. I have pulled down thousands of rounds of surplus ammo without a stuck bullet.

F. Guffey

 

[Lenard]

I have not followed all the pages on this "neck tension" post, but here is what I have found.

When I am doing load work ups, I always load extras in each powder amount. Then I pull the bullets on those loads that do not work out. What I discovered was that some bullets were much harder to remove, with lots of tension. Thus I started turning the necks on the 223 and now cannot feel a discernable difference when pulling them. Something else that I found helped, was to anneal each batch of brass after 2 firings.

It also made a huge difference in accuracy, with a big improvement.

 

[dmoran]

And now there is a tool designed to measure bullet hold in pounds when seating, and there is no chart for converting pounds to tensions.

F. Guffey

You can measure neck tension with many different units of measure, and in many different ways.
It is a derivative of measured force and stretch, that can be measured in pounds, grams, pressure, joules, inches, hertz, etc., etc.
Or it can be descriptively referred to and not measured at all, and simply used in reference to tension as a description, like so many do here and other forums for describing the amount a bullet is being held.

No different then your own measuring and referencing to it as "bullet hold", others are simply referring to the same thing using the word "neck tension" instead. Lots of different ways of measuring, and lots of words to chose from as the description.
D

 

[fguffey]

You can measure neck tension with many different units

Dmroan, thank you for that. I can't, I can measure interference fit, I can measure crush fit and that is outside of reloading. I have tension gages, all of my tension gages are calibrated in pounds with no equivalent to tensions.

F. Guffey

 

[Fotheringill]

I am a bit confused. I have read and seen "the" You Tube video.

Please advise on the question.

1. Measure the neck diameter of a fire formed case after neck sizing, non bushing RCBS.
2. I do not yet turn cases.
3. Seat a bullet.
4. Measure neck diameter from same place.

Q- Should the difference be divided by 2 before subtracting one measurement from the other?

 

[fguffey]

Should the difference be divided by 2 before subtracting one measurement from the other?

Should the difference be divided by 2 before subtracting one measurement from the other?


I would divide the difference by two to determine case neck thickness. There is no formula for determining neck tension. I know, sounds cool.


F. Guffey

 

[lightman]

It looks like the OP dissapeared during all of the fallout. Tom, if you check back in on this thread, I have a few suggestions. Put the bushing die back in its box and put it away for now. Put the expander back in your full length die and don't tighten the jam nut on it. Put this batch of brass aside for the moment and start over with another batch. Resize a few cases with your fl die and leave the expander loose (floating) and load and test them. Forget about neck tension for now. I'm not a fan of using bushing dies if you don't have a tight chamber and if you don't neck turn. So shooters do have success with them, this is just my opinion. Bushing dies can cause problems if you try to size too far with them. Your .007 is too far in my opinion. Leaving out the expander is causing damage to your bullet and/or case necks because the bullet fit is too tight. Someone else suggested using an expander die die and leaving the expander ball out of your fl die. Anyway, Good Luck with this project!

 

[savagedasher]

It looks like the OP dissapeared during all of the fallout. Tom, if you check back in on this thread, I have a few suggestions. Put the bushing die back in its box and put it away for now. Put the expander back in your full length die and don't tighten the jam nut on it. Put this batch of brass aside for the moment and start over with another batch. Resize a few cases with your fl die and leave the expander loose (floating) and load and test them. Forget about neck tension for now. I'm not a fan of using bushing dies if you don't have a tight chamber and if you don't neck turn. So shooters do have success with them, this is just my opinion. Bushing dies can cause problems if you try to size too far with them. Your .007 is too far in my opinion. Leaving out the expander is causing damage to your bullet and/or case necks because the bullet fit is too tight. Someone else suggested using an expander die die and leaving the expander ball out of your fl die. Anyway, Good Luck with this project!

My thoughts no matter what bushing size you use the expander ball is what going to give the final result . Not only does it determined the inside size it can change the head space.
Larry

 

[Kurt Blasser]

Newbie to competitive long range shooting and now newbie to reloading. I'm currently shooting a new Savage 12 F/TR in .223 and reloading the Federal Gold Match ammunition I have shot once. My conundrum is neck sizing the brass to adequately hold the bullet. I am using Redding competition dies. Neck sizing the cases according to directions, .001 to .002 down from the measured case neck size in the loaded round has left me with a goodly portion of the bullets able to slide through the case neck. I need some guidance as to how far to downsize the neck and have adequate bullet neck tension, without overtightening. One test I have read about is to insert bullet into prepped case and then push it against the bench and see if the oal changes. I have had to size way down to get anywhere near that spec, and then with a bullet impact hammer it will take 5-6 good whacks to dislodge the bullet. This seems to me to be too tight. Any advice and guidance welcome.

 

[RonAKA]

Newbie to competitive long range shooting and now newbie to reloading. I'm currently shooting a new Savage 12 F/TR in .223 and reloading the Federal Gold Match ammunition I have shot once. My conundrum is neck sizing the brass to adequately hold the bullet. I am using Redding competition dies. Neck sizing the cases according to directions, .001 to .002 down from the measured case neck size in the loaded round has left me with a goodly portion of the bullets able to slide through the case neck. I need some guidance as to how far to downsize the neck and have adequate bullet neck tension, without overtightening. One test I have read about is to insert bullet into prepped case and then push it against the bench and see if the oal changes. I have had to size way down to get anywhere near that spec, and then with a bullet impact hammer it will take 5-6 good whacks to dislodge the bullet. This seems to me to be too tight. Any advice and guidance welcome.

The rule of thumb that I have seen is to size until the neck is 0.002" smaller before you put the bullet in. In other words there is a 0.002" interference fit. Again another rule of thumb, but if you measure the OD of a loaded round -- say the factory ones, you want a bushing size that is 0.003" smaller than that - for that specific brass. The idea is that the brass will spring back 0.001" when it comes out of the bushing, to leave you with the 0.002" to be stretched to hold the bullet. This method however depends on the brass in the neck being a uniform thickness. If you change brands or lots of brass, you may have to measure again and change bushings to suit.

Keep in mind that 0.002" is not a lot of fit. Factory loads may have double that. You can't go beating on them with a hammer or they will move. In fact in some loads where the bullet is not seated far into the neck, I can pull the bullet out with my fingers.

 

[dkhunt14]

Newbie to competitive long range shooting and now newbie to reloading. I'm currently shooting a new Savage 12 F/TR in .223 and reloading the Federal Gold Match ammunition I have shot once. My conundrum is neck sizing the brass to adequately hold the bullet. I am using Redding competition dies. Neck sizing the cases according to directions, .001 to .002 down from the measured case neck size in the loaded round has left me with a goodly portion of the bullets able to slide through the case neck. I need some guidance as to how far to downsize the neck and have adequate bullet neck tension, without overtightening. One test I have read about is to insert bullet into prepped case and then push it against the bench and see if the oal changes. I have had to size way down to get anywhere near that spec, and then with a bullet impact hammer it will take 5-6 good whacks to dislodge the bullet. This seems to me to be too tight. Any advice and guidance welcome.

There is no set amount. If your going down .002 and the bullets are slipping that easy something is wrong. Either your measurement of a loaded round is off. The brass is off in thickness. Your brass is too hard and springing back too much after sizing or your bushings are not sized right. I have sized down as much as .008 and had good and sometimes better accuracy. Some guns can be tuned by more hold on bullet. Most of my guns like more tension. Matt