Lee Collet dies and neck tension

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Got my Lee Challenger Breech-lock press in yesterday, along with a set of Lee Collet (neck sizing) dies to load my 7x57 Mauser. After setting it up and re-reading the instructions, I was getting literally NO neck tension on my bullets with my test (unprimed, no powder) cases. My Hornady SST's would barely stay put, and my Sierras often fell right through.

So reading the directions, it said you could turn down the pin to gain more neck tension. I did that by chucking it in my drill, laying it on my vise and using a file to remove some material, then steel wooling it to smooth it up. Seems to have worked ( maybe a little too well ) but the two issues I need help with are:

1) Inconsistent neck tension. Most bullets I can feel the bullet seating with plenty of neck tension, but every so often I get one or two that again has very little tension.

2) Did I overdo it ? The cases with a lot of neck tension are really, really holding the bullet. As in, the bullet is sizing the neck when I press it in. Can you overdo the neck tension, or will the issue resolve itself when you press the bullet home?

I was concerned about this at first, but then thought about factory ammo -esp. with factory crimps - and those have a LOT of neck tension, do they not?

I am building hunting ammo that will likely get knocked around, so I want plenty of neck tension, but I also want it to be consistent and esp. not dangerous.

Thanks for any and all advice you can give.
 
I would double check the die adjustment before turning the mandrel down. "Hunting ammo" Why not just full length size the cases. No worry about fit in the field, plenty of neck tension, most likely more accurate than needed......
 
Thanks guys. I just use a neck sizing die in my .308, and have had great luck that way. It's a hunting rifle too, but I didn't see any reason to full-length size my brass since this is the only gun it's going to run through. I wanted the best accuracy I could get since I'm already struggling to get this gun to shoot under 2" and I didn't want to mess with case lube. So that's why the Collet die.

I will tinker with the adjustments some more. I can always get another mandrel from Lee for a few bucks, so I figured if I screwed it up, no big deal. Would just cost me a few days and dollars.

With the collet die, how do you know what depth is correct? I followed the directions and it said to seat it where the press made contact, then screw it in 1 turn. I guess I can experiment with the depth a little. I can see where too deep will get into the shoulder, but is there an issue with too shallow (i.e. only sizing 1/2-3/4 of the neck length)?
 
If the rifle/load is struggling to shoot 2 MOA, then neck sizing vs FL sizing is definitely not an issue. Sooner or later you are going to have a neck sized round not fit. Check them all before you go into the field. Or simply FL size, it isn't going to hurt you accuracy wise.

Adjust the die down a bit until it sizes the neck well, or gets to hard to pull the handle all the way down. It should size the neck OK if you get it screwed down enough. If it gets too hard before it sizes enough, the mandrel is too big or the collet is cut wrong. It takes a fair amount of pressure. The dies work well, but I wouldn't use it for hunting ammo.
 
Screw the collet die down 2 full turns after it contacts the shell holder. Size by putting a minimum of 25 pounds pressure on the lever. (Lee instructions)
Collet die pressure exertion

Posted by on 19 October 2011 02:29 PM

All of the sizing in the Collet die takes place at the very end of the stroke, when the ram/shell holder appears to bottom out against the base of the die. If you lean into the handle at this point, you will force the collet up into the die body, and cause the collet to squeeze the case neck down against the mandrel (the very end of which pops out the spent primer). About 25 lbs. of force is sufficient to resize most cases. If you are sitting in front of your press, just leaning your upper body weight into the lever is about right.

A good way to determine how much is necessary is to start the case into the die and feel the die remove the primer. Start using pressure and work up to what you think is about 25 lbs. Remove the case from the die and attempt to place the intended bullet in the case neck. If there is little or no resistance, repeat the process with slightly more pressure. When you have reached a point where there are vertical striation marks on the outside of the case neck or the intended bullet does not fit easily into the case neck, the correct amount of pressure has been achieved.
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1) Inconsistent neck tension. Most bullets I can feel the bullet seating with plenty of neck tension, but every so often I get one or two that again has very little tension.
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The collet die requires serious muscle on the press handle. If you use the same technique you use for regular dies, you won't exert enough pressure to collapse the collet.
2) Did I overdo it ? The cases with a lot of neck tension are really, really holding the bullet. As in, the bullet is sizing the neck when I press it in. Can you overdo the neck tension, or will the issue resolve itself when you press the bullet home?
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You probably overdid it. By reducing the diameter of the sizing shaft, you made it too small, so when you put pressure on the handle, you size the neck too much. The bulge you're seeing is proof of this.

I would order a new sizing shaft from Lee, and pay attention to how much pressure I put on the handle from now on.
 
Thanks Vern. I just didn't realize how much pressure you needed to put on the handle to get the neck to size.

I will order a new mandrel.
 
I measure the bullet. Personally I like .002 smaller than the bullet. If the collet is larger than that I polish it down to .002 below the bullet diameter. I do that with Lee full length sizing dies too. I've only had one .35 Rem FL stem that had to be polished down.
 
As Walkalong and a couple fellow members said, it's all in the pounds of pressure you put on the handle. When Lee advises "a firm 25 pounds" on the handle that is exactly what works.

You used a file on the mandrel expander plug? I love ya, you lunk. But a file on an expander plug is like using dynamite to move the furniture in your house. If you get inconsistent case neck tension with that expander, and you haven't figured out how to get consistent 25# on the handle, I'm not surprised that the outcome is inconsistent.

If you really want an undersize expander, buy one from Lee. They have instructions in the Instructions on how to order it. Cheap. Easy. Perfect.


OK. Now what do you do. If the brass that comes out of your collet die fits the chamber (no bullet just brass) you're probably on the right track, even with the monkey filed expander mandrel. Just use consistent 25# on the handle and see how it works. Eventually the brass will expand a little too much and will require full length sizing as Walkalong and others advise. Until then, use the Collet die as instructed.

But now you have a modified mandrel. What do you do? Go ahead and try the 25# on the handle and see if that gets more consistent case neck tension. When I first used the collet die, I got a 25# weight and used it as a gauge. I know it sounds dumb and elementary, but it works.
 
You used a file on the mandrel expander plug? I love ya, you lunk.
Click to expand...

Hey! I resemble that remark. :D

Yea, I get a bit carried away sometimes. I was trying to polish it down with fine grit sandpaper and steel wool, and nothing was happening. I don't have all day, I figured, so I got the mill bastard file out and something happened. LOL.

The brass that comes out does fit the chamber fine. I fired some rounds made with the manhandled, bullet-neck expander variable tension cases and they shot fine. Better groups than I got with the factory ammo in fact.

But I finally see what Lee and you guys are talking about with the consistent 25# of pressure on the handle. I wish there was some good way to measure that, but I'm sure I'll get the hang of it eventually.

I've loaded 100's of rounds of .308 with a Lee Loader (whack a mole) and never had to worry about being so precise. Maybe they made that with guys like me in mind, so we could get the hammer out and still not screw up. :D
 
" But I finally see what Lee and you guys are talking about with the consistent 25# of pressure on the handle. I wish there was some good way to measure that, but I'm sure I'll get the hang of it eventually."

Maybe this?
 
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Brilliant. I'm not surprised someone created this. I had that in my mind actually and was trying to figure out how to adapt my torque wrench to my press just this morning. I don't think it would be that hard to do. Sure would be nice to know when you hit the magic number though.
 
If your press is capable of camming over, run your die down to where it wont do that. If you take your time, you can feel the collet squeezing the neck to the mandrel, or at least I can feel it on my Rock Chucker. A consistent pull on the press handle is the key, as others have stated. I took a very little bit of material off my mandrel-Lee used to recommend no more than .001" by using a drill and 0000 steel wool. I get good and consistent neck tension now.

After 3 firings, I use the full length sizing die to just bump the shoulder back a little bit-maybe .002 in order to make sure the round feeds without effort.
 
Problem is the Challenger press. It's aluminum and has a LOT of flex. For the problems you state, I don't care for the collet neck size die.
I had a Challenger press. Gave it to my younger brother. He only occasionally reloads, with standard dies. It works for him.
BTW, I've broken TWO Lee "Reloader Special" JR presses. They are lite duty presses. I still have one that is dedicated to bullet sizing duty.

Get a "Classic" cast iron press, or RCBS Rock Chucker.
 
That's always the advice people want to hear right after investing in a new tool. LOL.

Thanks, but I think I'll make my Challenger press work for me. I ordered a new undersized mandrel from Lee and it should be here in a few days. I'm sure that will fix the problem. Until then, I've made and shot plenty of rounds with my badly mangled super-undersized mandrel, sizing the throats with the bullets and they still shoot better than any factory ammo I've run through that gun.
 
Put me in the been there done that camp. The Challenger is okay for pistol stuff, but I agree that it will eventually fail. In fact, mine blew up using a Lee collet neck die.
 
I had a Challenge press when I first started loading. It worked just fine and loaded a lot of ammo with it. Not a lot of rifle but some 556. I sold it (wish I didn't) as it was light weight and made a good traveling press mounted to a 3/4 piece of plywood. Could mount it anywhere.

The Classic is much heavier and has more leverage

I am sure my Wife has been at it longer than yours. Check before attacking things with files, Dremels and Hammers:D
 
I am sure my Wife has been at it longer than yours. Check before attacking things with files, Dremels and Hammers
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Probably so. Just 28 years with mine. ;)

And what fun would life be without files, Dremels and hammers? None at all, ha, ha.
 
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