The ultimate solution to neck tension

[Brians356]

Sinclair makes a die along with mandrels for various calibers. Does the same thing from what I see. Can someone tell me the difference?

The Sinclair Gen-II type allows the mandrel to float a bit, using a rubber O-ring. Here the mandrel is rigid with the die body.
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[Martin52]

....What assures that the case is also coaxial?
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I like Joe R's/Porter Precision's development for expanding case necks using a mandrel. The lack of coaxial alignment and resultant run out has stopped my past attempts to go this way even with a custom mandrel, hence I am re-visiting the bushing/expander ball scenario again. However, the Porter solution, perhaps with a rubber O ring could be the way to go. Interested to hear the answer to the question what assures the case is also coaxial though.

Martin

 

[BoydAllen]

FYI, in the past I have compared the runout of cases expanded for turning from .220 Russian size to 6mm. My RCBS press has die threads that are less tight than my Harrell's combo press, and I am sure that they are not as precisely aligned. The brass expanded with the Harrell press is, on average, straighter after being expanded. The worst results, that IMO were unacceptable, were the result of using a Forster B2 press that is designed to let dies float. It is my opinion that unlike sizing or pulling an expander back through a sized neck, floating is not desirable when inserting a expander mandrel down from the top. As an aside I have been told by bullet makers that the Lee Cast Iron Classic press has very good alignment, as well as the Redding O presses. Generally, the RCBS presses have required some work to bring them up to bullet making squareness and alignment. Back in the late 90s a prominent 1,000 yard shooter and organizer told me that his last sizing step was expanding with a mandrel, and that he had a set that were in half thousandth graduations. I have a PMA Tool expander die and mandrels that are very high quality. In that brand there is an option of carbide expanders. I have a couple of those, of different shapes for 6MM. The die secures mandrels with a large diameter set screw that is coaxial with the die. I think that this is a much better setup than those that use a set screw that comes in from the side.

 

[Joe R]

Sinclair makes a die along with mandrels for various calibers. Does the same thing from what I see. Can someone tell me the difference?

ranger3,
One of the difference is that the Sinclair expander die mandrels come in only one size, for my 308 the expander mandrel is .30685. My Hornady Neck Turning mandrel is .30495 so there is more play then Sinclair claims. Additionally, the steel used is not very hard because it starts changing after running it through a few hundred cases.

Having the mandrel hardened further is a bit of a problem because it is expensive and the heat process will slightly change the mandrel, straightness and size. I have gotten custom mandrels made for the Sinclair die using both D2/tool steel and carbide steel. The problem with that approach is that they are expensive, $60 each, and even grinding shops have difficulty achieving .0001 precision, so it takes 2-3 tries to get one just right.

To make matters even worse when I experiment with neck turning thickness of .014 to .010 (for my 308) that effects the amount of spring back from the expander mandrel, again changing the seating pressure as measured by the hydro press.

As you can see, I really need a bit of a library of mandrels ( https://www.amazon.com/s/?ie=UTF8&keywords=vermont+gage+pins&tag=accuratescom-20 ). By using the P3 (Porter Precision Products) die I can buy individual pin gauges to .0001 precision for only a few dollars and just grind a bevel on it.

Another added benefit of the P3 die is that it holds the mandrels consistently straight resulting in very little runout.

As you can see this has been an interesting journey towards precision ammo . Now the real challenge is learning to read the wind, but that's another story .

Kindest regards,

Joe

 

[Joe R]

I see. In the photo it's not clear that the collet is tightened on the mandrel. So the mandrel is coaxial with the die. What assures that the case is also coaxial?
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Hi Brian,
I know you like to ask lots of questions and I like that because it makes me think (a dangerous thing, I know). The way the collet holds the mandrel coaxial/straight is quite simple and ingenious. Because of its shape, as I tighten the collet cap/cover, the conical shape and smoothness of the collet seems to find the center of the die effortlessly. That's really cool isn't it. Simplicity is the ultimate sophistication.

Kindest regards,
Joe

 

[Frankr]

I hate to be MR Obvious but hence the reloading die with a expander ball. I read a article once where a very successful shooter said all his long range ammo he slightly turned his necks for uniformity and used a expander ball die. I thought about it and decided to try the difference between the use of just the FL bushing die and a FL bushing die with the expander ball in place. I think using the expander ball works well. I guess it depends what your accuracy requirments.
Maybe joe R's method is better than the old reloading die expander ball but I have found the old expander ball works very well.

here is a 3 shot group at 200 yards from a Norma 6XC brass unturned loaded on a redding FL S bushing die with the expander ball. It is not a BR rifle just A #4 sporter barrel on a hunting rifle. I find it to shoot quite well using this set up. now if I turned necks,anneal, used joe R method to expand my necks could I get it to shoot better. I am quite sure it might be a little better.I guess my point is expanding the neck after sized has been around since reloading die's I guess and It works well.

 

[Webster]

Well, ... a mandrel would control the inside diameter of a case neck much more precisely than any bushing ever can. It could also transfer neck thickness variances to the outside of the neck where it doesn't interfere with neck tension and bullet release. That's good isn't it?


Joe

View attachment 989647 View attachment 989648

I don’t understand this theory that high spots on the inside of a case neck get pushed to the outside by a mandrel. If there is a high spot 0.002” above the surrounding area a mandrel would push not only the high location outward but an area around the high spot. When you remove the mandrel it would return to its original shape since you are in the elastic region of deformation (spring back). The same thing with neck wall thickness variation.

 

[dkhunt14]

I don’t understand this theory that high spots on the inside of a case neck get pushed to the outside by a mandrel. If there is a high spot 0.002” above the surrounding area a mandrel would push not only the high location outward but an area around the high spot. When you remove the mandrel it would return to its original shape since you are in the elastic region of deformation (spring back). The same thing with neck wall thickness variation.

If this was the case you couldn't expand and turn brass. I measure pretty carefully at 12 places after turning and can hold .0001. Matt

 

[ab_bentley]

@Joe R

What's this doing for your ES spread? If the neck tension is the same, your powder measuring technique should become a bigger diving factor.

Adam

 

[Frankr]

I am going to ask how many of you have loaded rifle ammo on a regular FL die with a expander ball ?
I have been loading on those kind of die's since I was 16 years old.. And I can tell you I have had some real good shooting rifles and ammo of them regular die RCBS,Forster,Hornady,Redding to name a few. when I got into accuracy reloading we went to neck/bushing dies with tuned neck and then back to FL bushing dies with no expander ball. the expander ball was considered bad for accuracy but you know I have seen some real good shooting ammo of a regular FL die with a expander ball. The method Joe R is describing is kind of a more precise way to expand the neck more accurately but different sized expander balls have been made and most die makers will make you one to your spec or size. I have found FL sizing with a bushing die no X-ball and FL sizing with a bushing die with a expander ball both have their place but I do think using the expander ball does make accurate ammo and more consistent neck tension most of the time. So I am sure joe's method would work well.

 

[Webster]

If this was the case you couldn't expand and turn brass. I measure pretty carefully at 12 places after turning and can hold .0001. Matt

After further thinking about this your correct. If the mandrel expands the case enough there has to be some permanent expansion. My K&M expander gives a permanent increase in neck diameter. If never measured the before and after diameter. There should be some spring back. How big does the expander mandrel diameter have to be larger than the neck i.d. to get a permanent set?
Explain to me why there are other factors that determine the wall thickness besides the space between the cutter and the mandrel. How can the cut be larger or smaller than the space? This is something I never understood.

 

[jlow]

Jlow,
As I understand it, annealing is like a "restart" button on a computer, it takes you back to the beginning. As Donovan Moran once taught me, if you anneal once, you should anneal every time, and I do. My friend Ben Steinsholt took this one step further and he anneals before using the mandrel, and before resizing. I think that was very clever of him don't you?

Joe

After further thinking about this your correct. If the mandrel expands the case enough there has to be some permanent expansion. My K&M expander gives a permanent increase in neck diameter. If never measured the before and after diameter. There should be some spring back. How big does the expander mandrel diameter have to be larger than the neck i.d. to get a permanent set?
Explain to me why there are other factors that determine the wall thickness besides the space between the cutter and the mandrel. How can the cut be larger or smaller than the space? This is something I never understood.

I think a big part of that depends on how work harden/annealed level the brass is.

 

[Coolhand]

I bought a range of gauges in .0005 increments that helps identify the variance of internal neck dims of new Lapua .308 cases. The cases are sorted in lots and then run into a Lee collet die. Some time back during an afternoon beer and BS session with one of my shooting mates we tossed about the idea of making a die which will hold a pin gauge to make a mandrel but we couldn't come up with a suitable solution to hold the pin gauge.
After reading this post I soon realized what idiots we were, as sitting on the bench in my mates machine shop is a box of ER collets for his Turret Mill ! Thanks Joe !

regards
Mike

ranger3,
One of the difference is that the Sinclair expander die mandrels come in only one size, for my 308 the expander mandrel is .30685. My Hornady Neck Turning mandrel is .30495 so there is more play then Sinclair claims. Additionally, the steel used is not very hard because it starts changing after running it through a few hundred cases.

Having the mandrel hardened further is a bit of a problem because it is expensive and the heat process will slightly change the mandrel, straightness and size. I have gotten custom mandrels made for the Sinclair die using both D2/tool steel and carbide steel. The problem with that approach is that they are expensive, $60 each, and even grinding shops have difficulty achieving .0001 precision, so it takes 2-3 tries to get one just right.

To make matters even worse when I experiment with neck turning thickness of .014 to .010 (for my 308) that effects the amount of spring back from the expander mandrel, again changing the seating pressure as measured by the hydro press.

As you can see, I really need a bit of a library of mandrels ( https://www.amazon.com/s/?ie=UTF8&keywords=vermont+gage+pins&tag=accuratescom-20 ). By using the P3 (Porter Precision Products) die I can buy individual pin gauges to .0001 precision for only a few dollars and just grind a bevel on it.

Another added benefit of the P3 die is that it holds the mandrels consistently straight resulting in very little runout.

As you can see this has been an interesting journey towards precision ammo . Now the real challenge is learning to read the wind, but that's another story .

Kindest regards,

Joe

Joe you have solved my problem, I have a drawing here for a mandrel assembly much like yours. A buddy and I were having beer and BS session when we mulled over the idea of using specific pin gauges to use as sorting gauges for new .308 Lapua cases.
I have been using pin gauges for years to check the ID of new cases but doing by hand. I have one pin loctited into an old case for a handle which I use starting comparator, sort of like a go-no go internal neck sorting thingy. It works ok but your idea is wizard. If you didn't want to expand the necks you can still use it as a comparator. What I found was that even doing it by hand you can measure and feel minor differences in neck ID. So now with your die you can also get a feel of the resistance of the neck over the pin gauge, much like bullet seating.
The photo's of your die reinforced what a pair of idiots we are as not 10ft away from us under his bench is a set of ER Collets for his Turret Mill !! Duh !!

BTW . if you want to get reaaaal anal you can use XX Class pin gauges that are 0.00002" they are usually provided with a test certificate which testifies their tolerances BUT they go for around $30.00 each depending on diameter. Another gauge that I have considered using is a plug gauge ring that can be used as an outside neck diameter comparator BUT they don't come cheap, i.e a .3080" plug gauge is around $120.00.



regards
Mike.

 

[SG4247]

You guys make this way too hard.

Hornady bullet puller with the cam over handle that pulls the collet in. My collet is for a .270 Remington and fits all my .241" (6mm) and .261"(6.5mm) pin gauges in that range.

Bought the Hornady cam lock collet bullet puller #050095 with collet for like $35.00.

 

[Joe R]

@Joe R

What's this doing for your ES spread? If the neck tension is the same, your powder measuring technique should become a bigger diving factor.

Adam

Adam,
EriK Cortina once said that Holy Trinity of precision handloads are powder, seating depth and neck tension.

Powder regards to selection of powder and its measurement. This is pretty straight forward and can be solved by buying a good laboratory quality scale.
Seating depth is also straight forward, many of us experiment in .003 increments until we find what does best on target.
The toughest nut to crack is the neck tension. This one is challenging because there are so many parts to it. Here's an article titled Neck Tension 101 it will help.

Joe

 

[Joe R]

I bought a range of gauges in .0005 increments that helps identify the variance of internal neck dims of new Lapua .308 cases. The cases are sorted in lots and then run into a Lee collet die. Some time back during an afternoon beer and BS session with one of my shooting mates we tossed about the idea of making a die which will hold a pin gauge to make a mandrel but we couldn't come up with a suitable solution to hold the pin gauge.
After reading this post I soon realized what idiots we were, as sitting on the bench in my mates machine shop is a box of ER collets for his Turret Mill ! Thanks Joe !

regards
Mike


Joe you have solved my problem, I have a drawing here for a mandrel assembly much like yours. A buddy and I were having beer and BS session when we mulled over the idea of using specific pin gauges to use as sorting gauges for new .308 Lapua cases.
I have been using pin gauges for years to check the ID of new cases but doing by hand. I have one pin loctited into an old case for a handle which I use starting comparator, sort of like a go-no go internal neck sorting thingy. It works ok but your idea is wizard. If you didn't want to expand the necks you can still use it as a comparator. What I found was that even doing it by hand you can measure and feel minor differences in neck ID. So now with your die you can also get a feel of the resistance of the neck over the pin gauge, much like bullet seating.
The photo's of your die reinforced what a pair of idiots we are as not 10ft away from us under his bench is a set of ER Collets for his Turret Mill !! Duh !!

BTW . if you want to get reaaaal anal you can use XX Class pin gauges that are 0.00002" they are usually provided with a test certificate which testifies their tolerances BUT they go for around $30.00 each depending on diameter. Another gauge that I have considered using is a plug gauge ring that can be used as an outside neck diameter comparator BUT they don't come cheap, i.e a .3080" plug gauge is around $120.00.



regards
Mike.

Mike,
I don't know you, but I'm certain that you're no idiot. Actually I'm willing to bet you're a lot smarter then your average Joe. As I stated here, I'm not the one that solved this problem, it was Kenny Porter. I just got him thinking about the issue I wanted solved and presented a couple of ways (Hornady collet and Lee Universal decapping die) to tackle it. Kenny being a master tool and die maker was the one that saw where I was coming from and made the leap to precision tools he uses. The credit belongs to Kenny not me. I just happened to help him focus on my problem. But I do share in your excitement.

Another gauge that I have considered using is a plug gauge ring that can be used as an outside neck diameter comparator BUT they don't come cheap, i.e a .3080" plug gauge is around $120.00.

WOW, I had been thinking about finding a way to measure circumferences with precision but I have never heard of a plug gauge ring. I suspected that a professional had already solved it, but didn't know where to start. See, you've already repaid me.

What a great forum where we can all share and help each other out.

Kindest regards,

Joe

 

[ireload2]

You guys might want to consult an industry that specializes in bushings and other items that have holes produced in production quantities to tolerances of millionths. Grinders and hones can easily work to have those tolerances and have been for probably 75 years. Fifty millionths is .000050 or a half a tenth.
You can buy pins in .0001 increments from Deltronics. Just have a lot of ink in your pen when you write the check.
http://www.deltronic.com/literature/Deltronic-Gage-Guide-2014.pdf
Any bushing maker with an air gauge (look up Federal air gauge) can hone very close tolerance inside diameters.
http://www.threadcheck.com/content/mahr-federal-air-gages.asp
Sunnen hones are used to do the honing and have been around since the 1920s.
http://www.sunnen.com/about-us
The limits of precision are what you are willing to commit to afford greater precision and whether you can even tell if it makes any difference.

 

[ab_bentley]

You guys might want to consult an industry that specializes in bushings and other items that have holes produced in production quantities to tolerances of millionths. Grinders and hones can easily work to have those tolerances and have been for probably 75 years. Fifty millionths is .000050 or a half a tenth.
You can buy pins in .0001 increments from Deltronics. Just have a lot of ink in your pen when you write the check.
http://www.deltronic.com/literature/Deltronic-Gage-Guide-2014.pdf
Any bushing maker with an air gauge (look up Federal air gauge) can hone very close tolerance inside diameters.
http://www.threadcheck.com/content/mahr-federal-air-gages.asp
Sunnen hones are used to do the honing and have been around since the 1920s.
http://www.sunnen.com/about-us
The limits of precision are what you are willing to commit to afford greater precision and whether you can even tell if it makes any difference.

With all of these .00000s out there, it must be stated that those are in controlled climate facilities where contact is with robotics not human touch. The simple act of touching or warming the pin will change the diameter. So while you're seeing the fourth zero, it's really only true to the 3rd and probably the 2nd in all reality. Especially after running a few necks over the mandrel.

Adam

 

[Brians356]

Hi Brian,
The way the collet holds the mandrel coaxial/straight is quite simple and ingenious. Because of its shape, as I tighten the collet cap/cover, the conical shape and smoothness of the collet seems to find the center of the die effortlessly.

What centers the case on the mandrel+collet+die body? Does the case try to self-center on the mandrel, like with a Sinclair expander die?
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[savagedasher]

What centers the case on the mandrel+collet+die body? Does the case self-center on the mandrel, like with a Sinclair expander die?
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I have a question ? If I took a pin that was
242 . 0000 when I inserted in the neck of a case would the neck be the same size as where the shoulder is . Larry