Shoulder bump

[muleman69]

Will small base dies as well as body dies bump shoulders back ? If so what is the proper way to set them up?

 

[Bart B.]

Set full length small base dies up the same way.

Body dies usually don't have shoulders that touch case shoulders but typically move shoulders forward a bit as they squeeze body diameters down.

 

[LA50SHOOTER]

Set full length small base dies up the same way.

Body dies usually don't have shoulders that touch case shoulders but typically move shoulders forward a bit as they squeeze body diameters down.

A Redding Body Die act's the same as a Full-Length Sizer without doing Anything to the neck.
I like them for certain reloading scenarios where I want to Full-Length Size the body and "bump" the shoulder and address the neck with a separate neck sizer die & then a mandrel.

Body Dies (From Redding) can "bump" the shoulder the same as a Full Length Sizer die.

- Ron -

 

[ClassCat]

This Case was resized and shoulder bumped with a Redding 6MM PPC SBR. Part # 77211. Look at how close to the web the resize is. I get about 25-30 accurate firings before accuracy falls off. I can Shoulder bump .0005 and still catch the web. I use a regular #12 Shell plate holder that is basically stock. Don't bother with the shell plate holder kit, try the standard for your caliber first.

 

[dmoran]

Set full length small base dies up the same way.

Body dies usually don't have shoulders that touch case shoulders but typically move shoulders forward a bit as they squeeze body diameters down.

Never seen a "body die" that didn't have a shoulder, and never had one that didn't have the same ability as a Full Length die to sizing the body and shoulder. Other then not having the neck portion, they are chambered the same as full length sizing dies.

 

[BoydAllen]

I will respectfully disagree with the poster who wrote that body dies are not for bumping. They are. If you do not believe me, call Redding. They are essentially what you would have if you pulled the bushing out of a bushing type FL die.

In order to properly set up a FL, or body die you will need some measuring tools, a dial or digital caliper (I prefer dial) and something like what Hornady calls their headspace gauge which is not really a headspace gauge but a comparitor used to set dies.

One mistake that is commonly made is to set a die to bump the shoulder of a once fired case. In most cases those cases are not at their maximum head to shoulder dimension and for that reason you can simply set the die to duplicate the fired dimension. Of course primers should be removed or reseated out of the way before fired cases are measured.
If you are working with a tight case or you discover that setting the die to the same head to shoulder dimension as fired does not give easy chambering, speaking only for non semiautomatic rifles, you should limit your shoulder bump to no more than .002. If that amount of bump does not give you the bolt close that you desire then you need a different die, and that is why they make small base dies.

 

[MagnumManiac]

All replies haven’t addressed one issue...that is a small base die MAY NOT be required.

Many buy SB dies cause they ASSUME tight chambering is from the expansion line not being sized, this may be the cause in some cases, but if you HAVEN’T MEASURED, then how would you know?

I have found people using SB dies that don’t have tight chambers, what they have is a failure to MEASURE and recognise the true issue that when you size a case, even if only moving the shoulder .002”, that the body elongates into the shoulder. Without MEASUREMENTS before and after the event, they assume the tightness is the case body at the web.

Measure EVERYTHING before buying SB dies, you may find you are wasting your money unnecessarily.

Cheers.

 

[Bart B.]

I will respectfully disagree with the poster who wrote that body dies are not for bumping.

Good. Yup, my error

I keep forgetting modern body dies can bump case shoulders back. Decades ago when they were first used, only belted cases used them to size fired case bodies all the way back to the belt; not stopping several thousandths short like standard full length dies have done since day one.

 

[BoydAllen]

Good. Yup, my error

I keep forgetting modern body dies can bump case shoulders back. Decades ago when they were first used, only belted cases used them to size fired case bodies all the way back to the belt; not stopping several thousandths short like standard full length dies have done since day one.

Funny thing, a couple of years back a friend who is handy was having some trouble with sizing a .300 WM and I told him to buy a used FL die on Ebay and cut it off below the shoulder to produce what you described. It allowed him to size all the way to the belt and that solved his problem. Have a good one.
Boyd

 

[Bart B.]

Funny thing, a couple of years back a friend who is handy was having some trouble with sizing a .300 WM and I told him to buy a used FL die on Ebay and cut it off below the shoulder to produce what you described. It allowed him to size all the way to the belt and that solved his problem. Have a good one.
Boyd

That's how they were first made. Fired belted cases were resized back to virtual new dimensions with that body after full length sizing in regular dies and then shot as accurate as new ones.

 

[ireload2]

You cannot size all the way to the belt unless you cut some material off the bottom of the die. Belted case dies stop against the shell holder just like any other dies do.

Funny thing, a couple of years back a friend who is handy was having some trouble with sizing a .300 WM and I told him to buy a used FL die on Ebay and cut it off below the shoulder to produce what you described. It allowed him to size all the way to the belt and that solved his problem. Have a good one.
Boyd

 

[Dusty Stevens]

You cannot size all the way to the belt unless you cut some material off the bottom of the die. Belted case dies stop against the shell holder just like any other dies do.

I dont think id go that far. Some may but most never hit the shell holder.

 

[Dusty Stevens]

A proper small base die looks like a pistol die- no shoulder at all inside just an open top.

 

[BoydAllen]

A proper small base die looks like a pistol die- no shoulder at all inside just an open top.

I think that you are thinking of what is commonly called a ring die. If you buy a small base FL die from Redding it will be like any other FL die but the base ID will be a little smaller.

 

[MagnumManiac]

You cannot size all the way to the belt unless you cut some material off the bottom of the die. Belted case dies stop against the shell holder just like any other dies do.

You can’t size the belt anyway, in most cases the belt is adjacent to the solid web section, this doesn’t enter the die anyway because of the cutout in the die bottom.

After deliberately sticking a belted case (300WM) in a FL die, I sectioned it and could see that the expansion line IS being sized, the belt....no chance, it just doesn’t enter the die far enough. In fact if you measure the cutout in the die bottom for the belt to enter partially, it doesn’t even touch the case.
The belt doesn’t expand like the expansion line and doesn’t need sizing.

Cheers.

 

[ireload2]

You cannot push the top of the belt into the die far enough to size all the way to the belt unless you cut material off the bottom of the die. The belt clearance bore is deeper than the belt.

I dont think id go that far. Some may but most never hit the shell holder.

 

[ireload2]

No one said anything about sizing the belt. The way conventional dies are designed you cannot size the case body down to the front of the belt. There is always a gap due to the belt recess depth and the small lead into the die body.

You can’t size the belt anyway, in most cases the belt is adjacent to the solid web section, this doesn’t enter the die anyway because of the cutout in the die bottom.

After deliberately sticking a belted case (300WM) in a FL die, I sectioned it and could see that the expansion line IS being sized, the belt....no chance, it just doesn’t enter the die far enough. In fact if you measure the cutout in the die bottom for the belt to enter partially, it doesn’t even touch the case.
The belt doesn’t expand like the expansion line and doesn’t need sizing.

Cheers.

 

[muleman69]

All replies haven’t addressed one issue...that is a small base die MAY NOT be required.

Many buy SB dies cause they ASSUME tight chambering is from the expansion line not being sized, this may be the cause in some cases, but if you HAVEN’T MEASURED, then how would you know?

I have found people using SB dies that don’t have tight chambers, what they have is a failure to MEASURE and recognise the true issue that when you size a case, even if only moving the shoulder .002”, that the body elongates into the shoulder. Without MEASUREMENTS before and after the event, they assume the tightness is the case body at the web.

Measure EVERYTHING before buying SB dies, you may find you are wasting your money unnecessarily.

Cheers.

So if body elongates into shoulder what is the next step? Would you set dies to bump shoulder again? At what point will it stop growing?

 

[Bart B.]

You cannot size all the way to the belt unless you cut some material off the bottom of the die. Belted case dies stop against the shell holder just like any other dies do.

Agree. That's why we cut the die off above the belt relief then squared them up.

Larry Willis' collet die does the same thing.

An interesting thing about that belt is with new cases having a bit of shoulder clearance when stopped against the chamber belt ridge is they are well centered in the chamber when fired. Belts are quite square with the case axis. The reason new belted cases shot bullets so accurate.

 

[Bart B.]

So if body elongates into shoulder what is the next step? Would you set dies to bump shoulder again? At what point will it stop growing?

When a fired case headspace to shoulder equals that of the chamber is the time to bump the shoulder back when sizing body diameters down. It won't grow past that point unless you use a body die and want to use a cheater bar to close the bolt on such cases.

All of which is why I think a standard FL die followed by a squared bottom body die is best for belted cases. FL size 'em to .001" less than chamber headspace to shoulder then use the body die set to size the case body to .001" to .002" short of its belt. The case shoulder then centers case neck and bullet in the chamber when fired.