Neck Sizing and Shoulder Bumping

libertyman777

libertyman777

Are you gonna eat that....
Full Member
Minuteman
Nov 26, 2007
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Heflin, Alabama
#1
I have a set of Lee Collet Neck sizing dies and Redding Full Length dies for .308. I've been reading about this shoulder bumping deal and I believe I understand what's going on, but I have some questions.

I understand why the shoulder must be bumped back and I believe I can set up my FL die to do it. I also understand the reasoning on removing the expander ball and decapping assembly from the FL sizer so that the shoulder can be bumped without disturbing the neck.

If I understand correctly, the order of operation is to:

1) Realize the proper shoulder setback with the expander/decapper removed, run the fired cases through the die to set the shoulder back.

2) Then run these cases through the Lee Collet die to resize the neck and remove the spent primer.

3) Trim to length, chamfer, clean primer pockets, etc.

4) Check the cases to make sure they will chamber.

Is this correct?

Paul
 
#2
Re: Neck Sizing and Shoulder Bumping

You got 1 and 2 wrong.

1. When you run your case through a standard FL sizing die with the decaper/expanding assembly removed, you are not only bumping the shoulder back, but also sizing the neck.

2. You will not be able to run this case through a Lee collet neck die because the FL die reduced the neck by such a degree that it will no longer fit over the Lee decapping rod.

If you had a Type "S" bushing FL die, then you could remove the decapper assembly as well as the bushing so that the die shoulder bumps only.
 
#3
Re: Neck Sizing and Shoulder Bumping

I use the Lee collet to neck size and when the shoulder needs bumping I use a Redding body die. Both can be had for around $40 bucks. You can't beat the price. Lock Stock and Barrel sells most all dies seperately so you don't need to buy a set and only use one die. My Forster micro seater,body die and collet die was just about $100 bucks.
 
#4
Re: Neck Sizing and Shoulder Bumping

Then I guess I understood nothing. I could have sworn I read that all that was needed was to take out the expander assembly in a full length die set and I would be good to go. But what you said is correct. I checked the neck and it had been resized and the case stretched. What should I do with these cases, reinstall the expander and size them all again. I did run then through the collet die but I don't guess it did any good.

I think I've found what confused me. I can use the FL die to bump the shoulder back but as you said (and I discovered) that it works the neck. But if I remove the expander then I should use another method to adress neck concentricity i.e. neck turning. Is this correct?
 
#6
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: libertyman777</div><div class="ubbcode-body">Then I guess I understood nothing. I could have sworn I read that all that was needed was to take out the expander assembly in a full length die set and I would be good to go. But what you said is correct. I checked the neck and it had been resized and the case stretched. What should I do with these cases, reinstall the expander and size them all again. I did run then through the collet die but I don't guess it did any good. </div></div>

So they fit over the mandrel? If so, then you are good to go, albeit with more neck tension than the collet die would produce alone. My FL die sizes the neck so much it won't fit over the mandrel anymore.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: libertyman777</div><div class="ubbcode-body">

I think I've found what confused me. I can use the FL die to bump the shoulder back but as you said (and I discovered) that it works the neck. But if I remove the expander then I should use another method to adress neck concentricity i.e. neck turning. Is this correct? </div></div>

Sinclair makes vey nice neck expanding dies that expand the neck just enough to fit on the mandrel of their neck turning tool.

As it stands, you could reinstall the expander in the die and run the brass through again. Or you can load as is with the additional neck tension, or buy a Sinclair expander die or another expaner like a Lyman "M".
 
#7
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 918v</div><div class="ubbcode-body">You got 1 and 2 wrong.

1. When you run your case through a standard FL sizing die with the decaper/expanding assembly removed, you are not only bumping the shoulder back, but also sizing the neck.

2. You will not be able to run this case through a Lee collet neck die because the FL die reduced the neck by such a degree that it will no longer fit over the Lee decapping rod.

If you had a Type "S" bushing FL die, then you could remove the decapper assembly as well as the bushing so that the die shoulder bumps only. </div></div>

Is it ok to size the neck before setting the body back?
 
#8
Re: Neck Sizing and Shoulder Bumping

On my Dillon 550, I've run it several ways.

Station 1 = Lee Collet neck die
Station 2 = Redding body die
Station 3 = Redding or Forster micrometer seating die

or

Station 1 = Universal decap die
Station 2 = Lee Collet neck die with decap pin broke off
Station 3 = Redding body die
Station 4 = Redding or Forster micrometer seating die
 
#9
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock63</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 918v</div><div class="ubbcode-body">You got 1 and 2 wrong.

1. When you run your case through a standard FL sizing die with the decaper/expanding assembly removed, you are not only bumping the shoulder back, but also sizing the neck.

2. You will not be able to run this case through a Lee collet neck die because the FL die reduced the neck by such a degree that it will no longer fit over the Lee decapping rod.

If you had a Type "S" bushing FL die, then you could remove the decapper assembly as well as the bushing so that the die shoulder bumps only. </div></div>

Is it ok to size the neck before setting the body back? </div></div>

I've sized the neck first, then the body and body first, then the neck. It did not make a difference in terms of bullet runout.
 
#11
Re: Neck Sizing and Shoulder Bumping

It depends on the brand of brass ans neck thickness varies between brands. Or you can just get a Lee Collet Neck Die and not have to worry about bushings.
 
#12
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PSYOPS</div><div class="ubbcode-body">Help SH dudes!!

What size Redding bushing for .308?? There seems to be dozens.

Thanks. </div></div>

Just measure the outside diameter of your loaded cartridge (preferably several) about midway down your neck and deduct.002 from that number for your bushing size. Lets say that your measurement is .339 youll want a .337 bushing. Now depending on how much neck tension you want I would recommend several sizes of bushings so you can play with the neck tensions. I currently have 3 sizes for my Redding Neck die. They are .337, .336, .335 for my .308 cartridges. Keep in mind that not all your loaded ammunition will have the same diameter. All depends on the brass, bullets and if you neck turn your brass.... so take several measurements with your calipers. I hope his helps.
 
#14
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bdh308</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PSYOPS</div><div class="ubbcode-body">Help SH dudes!!

What size Redding bushing for .308?? There seems to be dozens.

Thanks. </div></div>

Just measure the outside diameter of your loaded cartridge (preferably several) about midway down your neck and deduct.002 from that number for your bushing size. Lets say that your measurement is .339 youll want a .337 bushing. Now depending on how much neck tension you want I would recommend several sizes of bushings so you can play with the neck tensions. I currently have 3 sizes for my Redding Neck die. They are .337, .336, .335 for my .308 cartridges. Keep in mind that not all your loaded ammunition will have the same diameter. All depends on the brass, bullets and if you neck turn your brass.... so take several measurements with your calipers. I hope his helps.</div></div>

Thank you, that helps a ton!
 
#15
Re: Neck Sizing and Shoulder Bumping

Are you loading for a gas or bolt gun?

Not to hi-jack but I was wondering how often it's required to bump the shoulder back? I just started reloading and have been using a lee collet neck die for my 1X+ fired brass. The results have been good with Federal brass however the Win I had laying around was too stiff and would not retain the neck tension. With more Federal then Win brass I decided not to turn down or order another mandrel from the die.

Is full length/partial full length (as some call is) required after several firings? Only when the bolt becomes tough?
Thanks
 
#16
Re: Neck Sizing and Shoulder Bumping

You are using the die incorrectly. I have no problem with Winchester brass.

Try screwing the die a few turns past the cam-over point and then feel the press compress the collet around the neck and squeeze it against the mandrel. Don't force it, but feel the sizing action.
 
#17
Re: Neck Sizing and Shoulder Bumping

I respectfully disagree.
I'm using a cam over style press and don't feel adding the human element of feeling the sizing action is consistent or correct. Screwing it in further will not give the brass more neck tension. It can only squeeze the neck until it hits the mandrel, adding more pressure only increases the chance of damaging the die. There is a reason people end up stripping the threads and blowing the cap out of the ass end of the die. It is a common practice to have several sizes of mandrels depending on brass, or so I have read. I'm no expert by any means but read endless pages of discussion about the dies before purchasing.

I think the lack of neck tension I get from Federal to Win brass is due to a variation of case thickness or spring back.
 
#18
Re: Neck Sizing and Shoulder Bumping

It does not increase the chance of damaging the die because you are positioning the die where the press does not have the same amount of leverage as it does at the cam over point. You are in fact lessening the chance of damage because by reducing leverage, you increase sensitivity or feedback you feel through the lever. Once you feel the collet pressing the neck against the mandrel, there is no need to pull the lever down further. You are not adding more pressure at all. You are adding less.

If you know why you are getting inconsistent results due to variance in neck thickness, why don't you adjust the die for the brand of brass you are sizing?
 
#19
Re: Neck Sizing and Shoulder Bumping

Are you still using the die to de-cap as well?

True, the damage is caused by shell holder contact while camming over with the die set too deep.

I'd rather set the press to cam over w/ light pressure and reduce the dia. of the mandrel as opposed to having to feel anything. But I have more Fed brass that retains NT than Win so FL sizing a few cases here and there is fine by me.
 
#20
Re: Neck Sizing and Shoulder Bumping

I think you'll find that there is a difference in neck wall thickness between Federal and Winchester (or Black Hills) with the Fed being thicker. So that the collet has to be adjusted closer to the mandrel to obtain the neck tension you desire.
 
#21
Re: Neck Sizing and Shoulder Bumping

Right, but my method does not require any adjustment. You do all the adjusting by feel as you pull the handle down, thus neck thickness is no longer relevant.
 
#22
Re: Neck Sizing and Shoulder Bumping

I don't see how this die is adjustable. The mandrel can be modified.
leecolletx350.jpg


Tips for lee collet dies
 
#23
Re: Neck Sizing and Shoulder Bumping

You adjust the die by screwing it closer or further away from the shell holder depending on neck thickness. That way when the press cams over, the collet compresses more or less depending on its relationship to the shellholder.
 
#24
Re: Neck Sizing and Shoulder Bumping

I like to use the Forster FL sizing die. I adjust the die out until I have bumped the shoulder .002 on a once fired case. I also take the expander ball out of the die. After I have bumped the shoulder back I run the case through the Sinclair neck sizing mandrel. This gives me uniform neck size(for proper tension). Also the neck mandrel drastically reduces bullet runout. IMO the expander ball is the root cause of bad runout.

This takes two steps. But by doing this I have the best of several worlds. I bump the shoulder a bit for better chamber fit. I get good neck tension with the Sinclair neck mandrel. I work the brass less while still achieveing a semi-FL sizing. And I reduce bullet runout by removing the expander ball.

This is an easy way to properly size your case for an accurate round that is very functional in most rifles. This works fine in my AR's also.

If you decide you still want to use the expander ball then I also like the Forster die. This die allows for substantial expander ball adjustment. The Forster dies and the Redding dies are very similar. I just like the Forster a bit better--only because they are slightly less price for basically the same die. And IMO unless you are turning your necks a collet die is of little use. Tom.
 
#25
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CumminsTruck97</div><div class="ubbcode-body">I don't see how this die is adjustable. The mandrel can be modified.
leecolletx350.jpg


Tips for lee collet dies </div></div>

It is also adjustable by putting a washer around the case to be sized. The brass is then partial neck resized.
 
#26
Re: Neck Sizing and Shoulder Bumping

Have you ever spun a case chucked in a power drill? Have you ever spun a case inside the shell holder while in the press. Are all cases spinning perfectly straight as you spin them? Or are the necks wobbling?

The case itself is the root cause of runout, not the expander ball.
 
#27
Re: Neck Sizing and Shoulder Bumping

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 918v</div><div class="ubbcode-body">Have you ever spun a case chucked in a power drill? Have you ever spun a case inside the shell holder while in the press. Are all cases spinning perfectly straight as you spin them? Or are the necks wobbling?

The case itself is the root cause of runout, not the expander ball. </div></div>

Of course the case causes runout. That is common sense. However how the neck is oriented to the case is basically the definition of run out. And yes the expander ball has alot to die with runout problems. The reason why is that when the expander ball is pulled back through the neck, the neck and shoulder is unsupported. And the expander ball can and will pull the neck off center from the casing.

I have no need to spin a case in a drill. I spin them in a Sinclair concentricity gauge with a dial indicator. Try my method one time, you will be suprised the difference you will achieve. Tom.
 
#28
Re: Neck Sizing and Shoulder Bumping

What I'm getting at is when the case neck is off center in relation to the base that sits flat in the shell holder, your Sinclair expander mandrel will not straighten it.
 
#29
Re: Neck Sizing and Shoulder Bumping

I have spent lots of time and money trying to find a way to straighten case necks.

The best way is to just fire them again. If the chamber was cut with a single reamer, it is concentric. If it is sized small enough to reach plastic deformation, the firing will get it concentric again.

With a bushing die, it is hard keeping a case concentric if it has neck thickness run out or if the change in diameter is large.
 
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