lee collet sizer adjust y neck tension again

  • Last Post 20 April 2015
Ken Campbell Iowa posted this 31 October 2012

a few fs issues ago john alexander discussed using the lee collet neck sizer...and adjusting it for inside diameter ....by raising and lowering it in a press.   GOTCH HIM ! ...well, partially ... maybe ...

1)  let us dream for a minute that squeezing the outside of the case neck to a given diameter.....either with the lee collet, or the exquisite redding s type bushing dies .... will produce the desired inside diameter .... 

FATIGUE CITY!  even john confesses that this requires neck thickness machining to a high (  low?  ... thirty  years a machinist and i still can't get that straight ... ) ... tolerance.   lots of very drugant work  ... i had a buddy who neck turned all his thousands of rounds of p.dog ammo.   ( side note:   yep his 22-250 shot 1/4 groups. )

2)  if one were to use the collet die correctly ....one would save a lot of hassle ...by not turning necks....and would also get consistant ENOUGH neck sizing.   the correct way ....is to mash the brass against the mandrel firmly....this makes the inside diameter the same .....   and the adjustment is accomplished by using different diameters of mandrel rods.

a good starting diameter for castered bullets is 0.002 under bullet diameter.  springback will be about 0.002 so this will give about a slide fit.

you are now probably wondering just where you are going to get an assortment of mandrel diameters ....    hey, i am just the messenger ....( heh heh ) ...but if i had my machine shop wired ...i would turn them out between centers on my hand lathe...so maybe mr. lathesmith would do the same if asked ...he advertizes  here ...   i have used as material both stressproof ... and fatigueproof ...both slightly harder than coldrolled ...for expanding rods ...lasted for 30 years so far ... fatigueproof is available in small quantity from brownells.  it also makes a great bushing for refacing your bolt after shooting old cases and pitting up your perfectly good rifle bolt (g ).

while we are close to the subject ....   i should mention that neck tension is not nearly as important to accuracy as is commonly reported ...it is BULLET CENTERING WHEN CHAMBERED  that is important.

neck tension...and crimping  ...  is important ...to keeping the bullet in the case ... in revolvers....and tube magazines ...etc.  but accuracy wise, no big difference ..that is because when fired, the brass neck is blown away from the massive bullet first thing... and leaves that putty-like lead bullet just hanging in mid-air... geeze no wonder i have to move those bean cans closer ...

speaking of fatigue, i b ken

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John Alexander posted this 31 October 2012

I agree with Ken that squeezing the case neck down against the mandrel should produce an inside diameter that it consistent enough without turning the necks to consistent thickness. This is also the way Lee apparently intended for the collet die to be used as well as an advantage of the collet die compared to the s type bushing dies which do require uniform neck thickness.

My reason for choosing to turn the necks instead of making extra mandrels is because for my needs I believe it takes less time to neck turn a batch of cases than make several mandrels. If I had Ken's equipment and skill instead of my toy lathe and little skill I might have reached the opposite conclusion.

My method also doesn't require changing mandrels when you decide to try a different neck diameter. Once turned my cases last well over a hundred reloads while using the collet die, so turning isn't something that has to be done often. Judging from past experience, the batch of 200 223 cases that I neck turned several years ago should be good for 20,000 to 30,000 reloads.

Of course another way to avoid neck turning is to buy Lapua cases which have uniform enough neck thickness without turning.

I also agree with Ken that neck tension isn't usually as important as often thought. My concern with neck tension is to have enough even though the bullet may be seated only just past the gas check and not having so much that seating the bullet causing the nose to upset (get fatter.) I often use pretty soft bullets.


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RicinYakima posted this 31 October 2012

John and Ken,

The reason I don't use the Lee squeeze die is that the one I bought was not in alignement with the the die body, nor the press ram. It was a real pain to use as it made the neck crooked with the case body. The second mandrel I special ordered from Lee was even worse.

However, I am in 100% agreement that neck turning's benefit is from making the bullet lie on the centerline of the bore. Bullets never strighten their angularity once the primer is activated!

For me, Sam Wilson's system still is the best even though you have to rework everything for cast bullets and it is slow in rounds per hour loaded.


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Ken Campbell Iowa posted this 01 November 2012

re:  misaligned lee collet dies....     as forrest gump pointed out .....” stuff happens “.   never trust anything made by man ...if made by god ...well,  take my wife ... (g) ...just kidding   ...

here is something i did that a person could consider:

first, i have several lee collet dies...then i use a hornady new dimension seater die ...then i have a lee factory  crimper if needed....   most of these work correctly.

but i also bot from harbor freight ... a collet closing fixture for 5c collets....the fixture is lever actuated, nicely weighted, and i just drop a plain mandrel in the case, stick the neck into the collet, and turn the lever tight , clamping the collet closed against the mandrel...  these fixtures are also available as air actuated in case you might want to do lots of cases ...

these collets are available in most any dia up to 1 inch ...and also in soft steel...or brass ..or nylon ...and right now, cheap on ebay, from mfg. ruined by obamacare etc.  ( not kidding ) ...

this makes the cases self-centering, and this assembly can be used at the shooting bench to load in the field..   also doubles as a handy pin vise...to hold a bore brush, primer pocket cleaner,  chamfer tool, etc.

just some trivia...  ken

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RicinYakima posted this 01 November 2012

The collet closing fixture sounds interesting. The concept should work, it just hasn't for me.

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linoww posted this 01 November 2012

I may be lucky but my 222 and 6mm Collet sets load good concentric ammo.


"if it was easy we'd let women do it" don't tell my wife I said that!

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joeb33050 posted this 01 November 2012

I'm having trouble understanding this. Is the following true? All other things equal, squeeze a case neck in a collet against a mandrel and the ID of the neck is determined ONLY by the mandrel diameter? If case neck hardness varies, spring back varies and neck ID varies as hardness and mandrel diameter? or All other things equal, squozed neck ID won't vary with neck thickness? Spring hard necks spring right back to where they started? Dead soft necks squeeze to mandrel diameter and stay there? Necks with varying thickness squeeze to mandrel diameter, then spring back according to hardness? How does neck thickness vary squozen neck ID? joe b.

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RicinYakima posted this 01 November 2012

joeb33050 wrote: I'm having trouble understanding this. Is the following true? (Yes, no and maybe, we don't know.)

All other things equal, squeeze a case neck in a collet against a mandrel and the ID of the neck is determined ONLY by the mandrel diameter?

(At the instant of compression, yes, after that no.)

If case neck hardness varies, spring back varies and neck ID varies as hardness


and mandrel diameter

(Yes, greater for 45 caliber than 22 caliber, as a percentage.)? or All other things equal, squozed neck ID won't vary with neck thickness?

(Not unless you squozed it enought to compress the mandrel within the normal limits of brass case neck thickness.)

Spring hard necks spring right back to where they started? ( Define how “hard” is hard and “right back".)

Dead soft necks squeeze to mandrel diameter and stay there? (Engineering books say “dead soft” has no spring back.)

Necks with varying thickness squeeze to mandrel diameter, then spring back according to hardness? (Yes)

How does neck thickness vary squozen neck ID? (Thickness, most unlikely within the range of case necks, 0.010” to 0.025". Even my little Redding press will generate over 14,000 psi with my 200 pounds of body weight on the handle. However, you could adjust the die to not compress fully against the mandrel.)

joe b.


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tturner53 posted this 01 November 2012

I use the Lee collet dies a lot. If anything, they are infinitely adjustable. On a side note, I've found a bit of grease on the outside of the collet fingers where they rub into the die makes them go smoother.

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joeb33050 posted this 01 November 2012

I guess I'm missing the boat. I don't/didn't turn 308 case necks, and the bullet seating force ?=? neck I.D./tension seems the same. And I have no idea how or why to adjust anything. I suppose I could turn the die out until the collet squoze less, then measure something. Yet there is a small height difference between squozen and not squoze at all. Another machine that I can't figure out. But it seems to work! joe b.

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tturner53 posted this 02 November 2012

The adjustments possible with the Lee collet die are up/down when screwing the die into the press, and the amount of pressure applied to the handle. The pressure/feely thing is a high art form and requires great finesse, but adjusting the depth of the die is simple. Due to the springy backy nature of the brass it is hard to get the neck ID the same as the mandrel OD. For me this a positive feature, I usually just want to barely size the necks. I just finished sizing/decapping a batch of 7.65x53 Argie brass using a Lee .303 Brit. collet die. The mandrel is .309, my neck IDs are now .311. It's the finesse.

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Ken Campbell Iowa posted this 02 November 2012

hi joe:

regarding rules for man made devices :  here is a cinnamon for your consideration:

have you ever noticed that all deer don't cross at the deer crossing sign ?

same thing for brass spring-back.

hope this helps.. ( g )


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John Alexander posted this 02 November 2012

I do a lot of sizing with the collet die and do a lot of measuring of the outside diameter of the neck as I size (I know the neck thickness because I turned the cases and can also measure thickness) so I know the ID I am getting. I seldom find that the ID is varying more than ).001” for a batch of cases.

I don't depend on “feel” at all. I start with the die backed out so it's not sizing and turn it down a little at a time between running the ram to it uppermost position with a case in place. When this turning the die down a small fraction of a turn gets to the place where it produces the neck OD I want to try -- I stop.

I don't give a fig what the spring back is because the final OD/ID is what I am interested in. I never (unless I have made a special mandrel which is seldom) force the brass down on to the mandrel. Cases are then sized by running the ram all the way up each time.

Like most reloading dies the collet die is made for jacketed bullets and squeezing the brass down onto is usually more than needed for cast bullets.

The batches of cases I use have have the same neck thickness and have about the same number of reloads and apparently have about the same amount of work hardening (spring back.) If you were sizing a bunch of cases where some had been sized 100 times and others were new, the difference in work hardening/spring back would probably cause varying OD/ID. However, this would be true of conventional sizing dies or s type sizing dies as well. But then one who works with such a mixed bunch of cases probably doesn't have as much interest in accuracy as in making a lot of noise so that shouldn't be a problem.

This procedure above works fine for me and saves time over the lubricating, sizing down, sizing up, cleaning cases, then belling the mouth (conventional sizing dies plus the M die.) It also produces ammunition that is accurate and the cases last a very long time.

I would be interested in hearing how others do it.


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robroy posted this 06 December 2012

John A: I have to agree wholeheartedly with the concept of working case necks to a minimal degree.  Squeezing to a small diameter, then immediately stretching the brass back to a standard diameter, that isn't right for cast and then stretching to the correct diameter, and putting a flare on the mouth, and then squeezing the flare back to spec, after ever so slightly stretching the neck by putting a bullet in it, just seems like too much work... on the brass and in terms of too many operations.  I think bringing the case neck to the appropriate size in one operation makes much more sense.  I've never tried bushing sizers.  I have and use several collet dies.  I like them allot.

Several years ago I read, on Varmint Al's site, of his method for loading his .17 Remington (I think).  When he was done fire forming, neck trimming sizing with a bushing die, and perhaps some steps I don't remember he claimed he could push his bullets into the case necks by hand.  This sounds allot like the slip fit that Ken C is talking about.   This is what I'm going to try for in my 22 Hornet.

I don't know if all the case prep is necessary for bughole accuracy.  Maybe I can shoot well enough to find, out one step at a time.

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Bob 11B50 posted this 19 April 2015

I have two of the Lee FCD dies one in 30-06 and the other is in 223 Rem.  I have used either yet other than to make up dummy rounds. I have not been able to dis-assemble the die nor have I been able to locate a mandrel in it.  Am I missing something here?   Bob 11B50

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onondaga posted this 19 April 2015

http://castbulletassoc.org/view_user.php?id=857>Bob 11B50

Yes, you are missing something, here it is Bob:

Your die identification nomenclature is incorrect. FCD is the abbrevation for Factory Crimp Die, FCDs do not have a mandrel, they are a crimping die. Don't ever expect to find a mandrel in an FCD.

This post is about neck tension with Lee Collet Neck Sizing Dies.

The only recommendation for adjusting Neck tension tighter with Lee Collet Neck Sizing dies is the mandrel abrasion method Lee instructions for the die discuss or the option of custom undersize mandrels that Lee offers for these dies. There is a little leeway with press operating lever force and case rotation per Lee instructions but that is only a tiny amount and less than about .0005", count those decimals- 1/2 of 1 thousandth of an inch. The operating lever force and case rotation tip will not work with a press that cams over that has been adjusted to cam over, That tip only works with a hard dead stop.

Custom oversize mandrels for Lee Collet Neck Sizing dies are also available for these dies to decrease neck tension.

You will not need custom sizes unless your chamber is not standard, your bullet diameter is not standard or your brass is not standard or has been incorrectly turned. Unfortunately, there is a list of hooey from people that don't understand what I have just said. There are also the occasional odd birds that think they have a good micrometer and that they are using it correctly, but they don't and they aren't.


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John Alexander posted this 19 April 2015

      Bob 11B50.

  I agree with the first four paragraphs of Gary's post.  Lee recommends using their Collet dies in the conventional “correct” way. Which involves the collet pressing the case neck down on the mandrel. They recommend a least 25 pounds of pressure on the press handle.  Unfortunately, like most reloading dies the collet dies are built for jacketed bullets, and this procedure will usually produce inside neck diameters that are smaller than optimum for cast bullets.  This too tight neck may distort the soft lead bullet during seating and ruin accuracy.  Lee's “correct” solution for this is to sell larger diameter mandrels.  This is a good solution but you will need a different mandrel for every inside diameter you may want to try.     There is an easier method that works well and has both advantages and disadvantages compared to the “correct” method. To achieve an inside diameter more suitable for cast bullets imply back off the collet die so the case neck isn't pressed down on the mandrel. This method has several advantages.  Nothing more to buy. You can vary the inside diameter and thus the seating force and neck tension as needed to do what works best for your bullet, alloy, and rifle by simply adjusting the die up and down.  It will work equally well with any press including those that cam over and those with a dead stop. It is also less work.  Instead of 25+ pounds force on the lever, two or three pounds will usually do it.  See my posts above (#2 and #13) for more explanation.     The theoretical disadvantage of this “non-correct” method is that the OD of the necks will be fairly uniform but the ID, which is what counts, will vary if the thickness of brass in the neck is non uniform.  If mixed lots and brands of brass are used together this might be a problem.  Otherwise this will seldom make any difference at the target.  It may be an issue if you are CONSISTENTLY shooting 5 or 10 shot groups of less than an inch.  If your groups average two to three inches, as with most CB shooting, you have other more important things to think about.  However, for best ID consistency a shooter should buy match quality brass that has uniform neck thickness or necks should be turned to a uniform thickness. If you do either, this method will produce extremely consistent inside neck diameters.     This non- correct use of the collet dies seems to disturb some shooters because Lee hasn't sprinkled holy water on it.  But it works and works well if it's limitations are understood.  Some competitive shooters have been using collet dies this way for many years, going to matches, shooting competitively in front of witnesses, and sometimes even winning.     John  

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onondaga posted this 19 April 2015

http://castbulletassoc.org/view_user.php?id=6375>John Alexander

You have some great points there and they will work, but with less than optimal consistency for a match shooter with nonstandard chamber, bullet size or brass lot. Lee recommends the custom mandrels for the specific reason that up/down die adjustment and changes in operating lever force are less consistent than full operating force and a correct mandrel size for a custom fitting job for a serious match shooter with special needs.

They are not making big bucks on custom mandrels, they are losing money to satisfy a tiny volume of customers with a specific need . It is a cheap service done on an “as ordered” basis. Check the price for the custom mandrels at these links below. They are cheap in price.




I am talking $5 or $10 for a custom part here. This is hardly worth complaining about when you are tagging these on to a larger order to absorb the shipping cost or you don't live down the street from Lee and can't walk over there to save the shipping cost.

Custom Collet Neck Sizing Die sets for unlisted calibers to your specification are also available from Lee, those aren't cheap. The adorable and brilliant Stephanie Lee can help you with those at 1-262-673-3075.


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John Alexander posted this 19 April 2015

Gary wrote: You have some great points there and they will work. Lee recommends the custom mandrels for the specific reason that up/down die adjustment and changes in operating lever force are less consistent than full operating force and a correct mandrel size for a custom fitting job for a serious match shooter. Gary,  I am a match shooter of sorts.  If you try the method I mentioned and don't get consistent ODs and IDs (when using turned necks and brass that has been reloaded the same number of times) you are doing something wrong.  I have used this method for years with brass that has been turned to a uniform neck thickness.  I measure the OD of the sized cases early and often.  I measure hundreds of sized cases in a match season.  I seldom see a measurement that is over .0002 from the target diameter and then only by an additional 2 or 3/10,000". When using the mandrel for some jacketed loads I get  no better consistency.   

I am using a Lee press with a dead stop (my cam over type press works just as well) and it only takes light pressure to reach the stop -- no judgment of force on lever involved. I have used this method over the last 15 years for five different match rifles with different chambers using different bullet diameters. It always produces very consistent diameters. 

I certainly didn't mean to imply that Lee recommends different sized mandrels to make money. Like you, I understand that it is good customer service.  I have reloading equipment from Lyman, RCBS, C&H, Hollywood, Redding and others but practically all I have bought in the last 20 years has been Lee and not because of the fair price although that helps.

Lee Precision has been a generous supporter of the CBA and in my opinion has done more to encourage cast bullet shooting than any other reloading equipment company. John   

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onondaga posted this 19 April 2015

http://castbulletassoc.org/view_user.php?id=6375>John Alexander

We are good John! For a moment I thought you were taking a dig at Lee.

I think those custom parts are so inexpensive that it is silly and I was attempting to be humorous.

Friend Gary

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LWesthoff posted this 19 April 2015

In Fouling Shot 179 (Jan. - Feb. 2006) Bob Sears posted the following:

"Collet sizing offers many advantages. Lee collet dies size with no need to lubricate case necks or the necessity of cleaning the lube off afterward. More important, they avoid passing the neck over an expander which can stretch the case as well as pull the neck off center. Neck expanding tends to worsen any eccentricity between the inside and outside diameters. Collet sizing over a mandrel tends to make it better."

Sears then goes on to suggest shortening the collet fingers by “about .03", below the end of the trimmed case. He puts a fired case in the collet to support the fingers while the end is turned off. He points out that cases sized in the shortened collet need no chamfering at the mouth in order to seat the bullet, and the unsized mouth helps center the front of the case in the chamber. “Military and other rifles having loose chambers” he says, “stand to benefit most from the centering guidance of unsized case mouths."

I've tried it, and it works like a charm!


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