Term: Bumping the shoulder

[JWFilips]

Hi Folks,
I guess after loading all these years I should know what this means, however I have only ever done; Full length sizing, Partial neck sizing ( in FL die) and Neck Sizing ( in Neck sizing dies).

I guess I'm really not sure what the term "Slightly bumping back the neck" means or how it is achieved and why it is necessary?
Is it a method for not over working the brass?

I usually fl size..... then once fire formed......I then neck size for 6 to 8 times......

After that many firings I anneal the necks and FL resize again, and continue the above process

 

[Rick]

On brass that starts to get hard to chamber using either the NK or FL die set to slightly move the shoulder back (bumping the shoulder). Slightly is a key word because you can easily cause excessive head space with brass that head spaces on the shoulder.

 

[Brad]

Hornady now makes the Stoney Point headspace tool. It uses a bushing in your calipers to measure to the datum line on the case. You can then size a case and measure. This lets you adjust the die to bump the shoulder back the desired amount. With some practice you can easily get .001-.002 repeatable.
Best tool I know of for this kind of stuff. Why geusss when we can know?

 

[JWFilips]

Doesn't FL sizing put the shoulder back to normal spec?

 

[Rick]

Not if you have the die set to size just the neck and stop short of touching the shoulder. Thus the term "Bump the shoulder".

 

[Kevin Stenberg]

Just guessing. FL sizing sizes to specks, not your gun chamber. Unless sizer is set for the chamber.

 

[Eutectic]

Brad's idea is the way to go. I've done a similar technique for years using a piece of handgun brass that touches shoulder at about the datum line. I mic the overall length of this setup and can easily set shoulder back .001" or .002" or more if needed.

Bumping the shoulder the other way is the tricky one! Here I start with a blind shell holder (no primer hole) I set the full length die out what I want. I seat a case with fired primer still in without the expander rod in the die. I measure the neck I.D. with the case in the die as described. I machine a little 'punch' from drill rod to a light press fit into neck. Eye dropper the case full of water. Insert your punch and tap a couple times with a small hammer. Wa-lah! The shoulder moves forward! I have even used this method to form .30 Gibbs from '06.... Cases that headspace tight enough to use them with full loads without fireforming. I've used just the full length die as well on the vise anvil. Here you will need to machine a donut shim the thickness required to place the 'new' shoulder where you want it inside the die. Seat the case into the die using a soft hammer tapping the top of the die down against the donut shim. This is fast and convenient with no stress hammering against your press ram. Shoulder can move forward too much if you tap too much so it may need to be positioned back to exact by Brad's method above. This method is probably better for major forming or movement as the .30 Gibbs mentioned above.

Pete

 

[waco]

I'll agree with Brad here. I have the Hornady tool with the bushings used on a set of calipers. Very easy to use. Very consistent. Very repeatable.
This comes in really handy with very expensive brass that you don't want to work harden any more than necessary.

 

[358156 hp]

Ingenious Pete. I used the same idea in the past to decap berdan brass. I never considered using it to blow a shoulder forward.

 

[JWFilips]

Ok So I think I'm understanding.....If a full length die is adjusted to size most of the neck....Then adjusting it down slightly more it starts touching the shoulder ( moving the shoulder back).
And this happens before the head of the case is reduced ? Correct?
So it is somewhere between sizing 90 % of the neck and full case sizing

 

[waco]

Jim. I have a Redding bump die for my .338 Lapua Mag. This die does not touch the neck at all. It will only set the shoulder back as desired.
I have not tried to manipulate FL size dies for this job.
Walter

 

[waco]

I guess they call it a body die.

 

[JWFilips]

Wow....I have been reloading since 1980 & I'm learning new stuff! This is a great place!

 

[smokeywolf]

I have occasionally screwed up and moved the shoulder back too far on '06 cases for a model '95. Usually then just relegate those cases to the '03. I'm definitely going to try Pete's method for bumping the shoulder forward.

 

[Brad]

Smokey, you could easily make a tool to replicate the Hornady tool. Pretty simple design really. Just a matter of using the right bushing for the datum line diameter.
Thumb screw holds it to caliper jaw, set screw holds bushing in place. Deprime case without sizing to eliminate primer from giving error. Then measure, size, repeat until shoulder is moved the amount you want.

When I shot high power I used this for a .002 bump with each sizing. I also used an O ring under the lock ring. Get die set right and make a small paint line on lock ring and press. Snug to match lines up and it is repeatable time after time.

 

[USSR]

The term is typically used when someone is neck sizing rifle brass. Eventually, the brass becomes hard to chamber due to the shoulder moving forward. Redding handles this with their body dies, which resizes everything except the case neck. Other manufacturers push the case shoulder back without resizing the rest of the case body. When I was shooting in 1,000 yard F Class Competition, I full length resized my brass in 2 separate and distinct operations: first I resized the body and bumped the shoulder back; and then I neck sized using bushing dies to get the exact amount of neck tension that I desired. Hope that helps.

Don

 

[JSH]

A slippery slope.
I have had body dies that would bump the shoulder and not touch the the neck. On the other hand I have had body dies that would only size the base of the case and would not touch the shoulder, thus needing a "bump" die.

Some folks load a generic type of load somthing they can shoot in mutiple guns. FL sizing should be done here for trouble free shooting.

If you are going to bump shoulders, that brass should be used in a specific gun for best results.

May be preaching to the choir, but thought I would make sure all were aware of this. Buddy of mine bumped the shoulder on a large bunch of brass he loaded. It would work in some guns and not in others.
I may over analyze things, but my generic ammo is FL sized. That is not always a given either. I learned that the hard way when I started in with the AR's again. I have been told by numerous people that the chambers are generous. Well mine falls on the small end of things. I had to go with a small base sizer to get it to function.

 

[USSR]

I have had body dies that would bump the shoulder and not touch the the neck. On the other hand I have had body dies that would only size the base of the case and would not touch the shoulder, thus needing a "bump" die.

??? Body dies are designed to bump the shoulder and not touch the neck. If a body die does not bump the shoulder, it is either defective or not screwed in far enough in the press.

Don

 

[Tony]

Redding males a competition shell holder set. 5 shell holders come in a plastic storage box. Each shell holder is incrementally thicker: + .002", + .004". +.006", + .008", + .010". Once you determine how long your chamber is you can use the appropriate shell holder and screw the F/L die all the way down. I have these sets for the .222/.223 Remington family, the .30-06 and the H&H family of cartridges. That will cover a lot of cartridges. If the datum line of your ammo matches your chamber you do not, practically speaking, have excess headspace and your brass will not stretch nearly as much. The comp. shell holders work GREAT with the Redding Type S Competition Bushing F/L sizing dies.

 

[Intheshop]

Be aware of work hardened brass,it's ability or "willingness" to be sized/formed comes into play.Proper annealing isn't just for reducing split necks.....it's also a requirement when holding really tight tolerances on your case work.

Eutectic,thanks for the brain jog.....old trick for certain mechanic'n procedures.Clutch pilot bearing removal is done "hydraulically" quite often,amongst others.