Trouble with Lee Collet Neck Sizing Die - Bumping Down Shoulder

[Ruger 15151]

Hi guys

I have been loading .308 for a while. I use the Redding Competition Bullet Seating Die and the Redding FL S-Type Sizing Die (with changeable bushings) to size the neck and push the shoulder back .002. However, I am on a mission to reduce my case run-out. Fired cases need the necks sized down about .011 to get proper neck tension, Redding says that sizing that much all in one step will cause the run-out. They say to do it in at least 2 steps using a neck bushing that sizes the first .006 and then a second that sizes the remaining .005. I still get more neck run-out than I would like.

I do not turn the necks so I know I will get some run-out as a result of varying case thickness. However, I should have the same run out on a sized case as I do on a fired case unless the die is introducing more runout. I have tried o-rings under the die body which cuts the runout in half.

I have read on several benchrest and long range precision shooting forums that many are using the LEE Collet Neck Sizing dies to initially size their necks down before running them through a S-Type Bushing die to get their final neck tension.

So.... I purchased a Lee Collet Neck Sizing Die in .308. It will size the necks to within .001-.002 of what I need which is exactly what I want. I'll run them through a FL sizing die to finalize the neck tension and bump the shoulders back.

PROBLEM.... The collet die is also bumping the shoulder about .004. I have adjusted it (as per several suggestions) so that it touches the shell holder and then is turned in 2 full turns so there is not cam-over on my T-7. The directions say that it will take 25 lbs of pressure to form the neck. However, I have put much less than that, just lightly sizing the neck a few thousands and it begins pushing the shoulder back.

Many swear by these dies to reduce run out but no one mentions that it also bumps the shoulders in the process. Lee technical support says that it should not be bumping the shoulders either but could not find any issues with me die setup.

For those of you that are familiar with these dies, any ideas as to what I am doing wrong?

 

[Rule3]

Watch this video. Much like the collet crimp die if the "petals) get to tight they will jam, stick and mess things up.

 

[243winxb]

https://support.leeprecision.net/en/knowledgebase

 

[243winxb]

You can partial neck size with the Lee Collet Die by getting a washer of the thickness you want and hole large enough to loosely fit over your case. Place the case in the shellholder, put the washer down over it, and resize. Whatever thickness of washer you use will leave that portion of the bottom of the neck unsized.

The unsized part of the neck will form to the chamber, centering the round in the chamber. Better accuracy.

 

[Ruger 15151]

Thanks for all the suggestions.

However, the collet is not stuck closed. The shell is moving into the die. I start about a turn above the shell plate and turn it down until I can start felling it size the neck. I have tried turning the die in a 1/16 of a turn and then measuring the neck so I know exactly where it start sizing. I also measure the shoulder with a comparator. As soon as the neck starts to size more than about .002, the shoulder also starts to move.

I am not putting much pressure on the press at all. I could see if someone is really leaning on the arm that it might force the neck toward the shoulder. However, I am not applying nearly enough pressure to collapse the case.

I borrowed a friends die and it does exactly the same thing.

I wish I could find an answer.

 

[243winxb]

Lee-
If you are using the Collet die in an RCBS Rockchucker press, or a similar design that toggles over center at the top of the (ram) stroke, this applies far greater force than is necessary to resize just the neck of the case, and can damage the die or collapse the case. To correct this situation, adjust the die two full turns into the press after the die contacts the shell holder with the ram at the top of its stroke, rather than one as in the instructions. This will stop the press before it gets to the toggle over point. With a press without having an over center feature, apply about 25 lbs. of pressure to the handle once it bottoms out to resize the case. On most presses, this translates to over 600 lbs of pressure on the ram.

I guess- A smaller mandrel may be needed, so that less pressure is applied to the handle?

 

[Ruger 15151]

Thanks for the replies. I was really scratching my head on this one. However, I think I found out what the issue was.

I prefer using a Sinclair comparator and inserts. However, I tried measuring the cases with my neighbor's Hornady comparator and it showed that the shoulders were not getting bumped. I decided to use a black marker on the shoulders and spun them in the comparators to see where they were touching the shoulder. It turns out that the Hornady locates on the middle of the shoulder and the Sinclair right at the junction of the shoulder and neck. The collet neck sizing die was effecting that small area only but when measuring with the Sinclair gauges, it showed the cases were shorter which could only mean that the shoulders were being bumped...right?? Or at least that was what I was thinking. However, since the Hornady contacts the shell in the middle of the shoulder, it showed that the shoulder was not actually moving.

When I thought about it, I realized that if the collect is sizing the entire length of the neck including the base where it transitions to the shoulder, its going to move that area slightly as well. Since the Sinclair gauge touches the case right in that area, it had me thinking the shoulders were getting bumped.

Had I measures the case with the Hornady instead of the more expensive Sinclair with fancy honed stainless steel inserts in the first place, I could have saved myself a lot of headache.

 

[tcoz]

https://support.leeprecision.net/en/knowledgebase

View attachment 903822

This is exactly the problem that I experienced due to my having run the die without a case being inserted. I ended up buying a new die.