Shoulder Bump-De-prime first?

[BucksnDucks]

I have a new 280 AI that I plan to fire form brass and shoulder bump with FL sizer. I've been reading past posts and watching a few videos. My past reloading I just full length sized, removing the primer at same time. I'm now looking for more precision.
It seems most are suggesting to de cap with a universal die then start the shoulder bump process. Can someone explain why to de-prime first as opposed to punching the primer with FL die as would normally be done with a FL RCBS die with adjustable decap pin. My apologies if I don't see the forest through the trees, just wondering why the extra step.

 

[Brian in Montana]

I've got similar questions. I've always just rammed brass through a full-length resizer, de-capping in the process. I always hear about a shoulder bump, but I'm not entirely sure I even understand exactly what it is.

So help me out here, correct me if I'm wrong, but I think it refers to how far into the resizing die the casing travels - as in, is the shoulder pressed all the way up into the die, stopping because it can go no further, or just "bumped", which if done correctly would leave a couple thousandths of an inch in the firing chamber. ??

 

[marksjeep]

When you first set up your sizing die (assuming standard FL sizer), it's good practice to use headspace gage/calipers or something similar to measure the brass and set up the die, such that the resizing is sufficient for your chamber, but not excessive. When doing this initial setup, the brass should be decapped first, as any primer protrusion will skew the measurements.

Once the die is set up, I don't know if it makes that big of a difference to do those steps separately. I personally decap and resize in the same step. "Bumping" the shoulder is just pushing the shoulder back a few thousandths. Again, enough to function reliably in your chamber, but perhaps not pushed back enough to work in every chamber.

 

[BucksnDucks]

When doing this initial setup, the brass should be decapped first, as any primer protrusion will skew the measurements.

Ok, thanks. I suspected it was as simple as that. I appreciate it.

 

[BucksnDucks]

I've got similar questions. I've always just rammed brass through a full-length resizer, de-capping in the process. I always hear about a shoulder bump, but I'm not entirely sure I even understand exactly what it is.

So help me out here, correct me if I'm wrong, but I think it refers to how far into the resizing die the casing travels - as in, is the shoulder pressed all the way up into the die, stopping because it can go no further, or just "bumped", which if done correctly would leave a couple thousandths of an inch in the firing chamber. ??

There seemed to be an overload of information and some debate about this on the net the last couple years. Some of the easiest to follow videos I saw were from a bench rest shooter, Eric Cortina (I think I got name right) and a guy from Long Range shooters. Seemed to make a lot of sense to me. All about getting more precise brass for a particular rifle, than producing a one size fits all rifles cartridge. Should be easy to find on Youtube. If not I can go back and find a link if you're interested.

 

[cahunter805]

I usually set my die up to bump the shoulder .002 as measured with a Hornady headspace gauge. They use the same body as their comparator for measuring off the Ogive also.
Most instructions that come with reloading dies are very generic and are to ensure that the caae will chamber in most any chamber. They usually are greatly over sizing the brass.
I recommend backing off your FL die about 1 turn and then slowly adjusting it down until you achieve the desired shoulder bump for your rifle.

 

[BucksnDucks]

Cahunter,
After you find the sweet spot and lock down the die, do you still de prime separately or just punch the primers at the same time?

 

[cahunter805]

Cahunter,
After you find the sweet spot and lock down the die, do you still de prime separately or just punch the primers at the same time?

I don’t deprime separately. I don’t understand the reasoning for that to be honest especially if you are using a FL die. I just adjust the die until I get the bump Im after and then set the decapping pin to de prime after that.
If you are after more precision in your handloads I’d recommend switching to a quality die set like a Redding FL bushing die and seater. I’ve found the normal RCBS dies to usually produce a bit of runout.

 

[WapitiBob]

If you are using gage pins to set neck tension you will decap separately.

 

[Don Fischer]

What's actually happening when when the shoulder is being bumped is min FL sizing. Rife chambers are mostly between SAMMI min spec and max spec. By bumping, I call it partial FL sizing you are actually FL sizing only enough to make the case fit that particular chamber. Some time guy's run into problems with excessive headspace and usually by partial sizing you can adjust for the oversize chamber, With belted case's you'll now and then have a chamber that after two or three firing's will develop a bright ring around the head in front of the belt. The head space is usually fine but the chamber is sloppy. The fix is partial sizing. Only size the case back enough to make the body of the case fit the chamber. Then the shoulder f the case stops the case from pulling on the head which causes the problem in the first place.

I don't have the tools to measure thing's so I first neck size with an FL die. Set the die so the shoulder doesn't get moved at all. Take's a couple time's doing that and then the case will no longer fit the chamber, to big. At that point I start turning the FL die into the press each time getting a bit closer to the shoulder after each pass, try to chamber the round. If your close you'll be able to feel the shoulder rub when you close the bolt. run the case through again until you no longer feel the case rub. Each time the bolt won't close easily, turn the die in about a quarter turn and size again till you can no longer feel the case rub. At that point I lock the ring on the die and dedicate the die to that particular rifle.

The bump being refered to happens each time the shoulder get's moved back just a bit. When the shoulder is moved the entire case is actually moved just a bit at the same time. You actually FL size the case to fit your action.

I have two 243's right now and each has it's own set of dies. Both set's FL size the case to fit a rifle. and one chamber is slightly larger than the other. Because of that, the case's partical sized for the bit larger chamber will not chamber in the other rifle but the chamber closer to spec, smaller, will let the case's chamber in both rifles. Neither rifle has excessive head space it's just that the difference between min spec and max spec chamber is enough to not allow a case sized to max to chamber in the min chamber. For FL sizing according to direction's with die sets, the die is turned down all the way to the shell holder with the ram up. I think it's RCBS that then say's to lower the ram and turn the die down just a bit more. I forget why but it's in the directions, it's called over camming. When you do that you will return the case to min spec and it will chamber in all chamber's for that cartridge!

One other thing I do is I use only one bullet in any rifle and I set the bullet seating die to seat the bullet just short of the lands. Like that you could well run into a rifle set for max cartridge length or min cartridge length and one round may well push the bullet into the lands raising chamber pressure. Look in your reloading manual and everyone I've had give the same OLL, Overall Loaded Length for the same cartridge. Every thing about measurement's in the manuals take in to account that the loaded round must fire in every rifle for that cartridge, result's are min measurement to fit all.

I think whoever came up with the term "bump the shoulder" simply used a term to describe moving the shoulder just enough to have the case fit the individual chamber. Keep in mind you don't have to, "bump the shoulder" or partical size, simply size to sammi min specs and the round will fit your rifle and every other rifle in that cartridge and fire properly. Even in the belted cartridge with a sloppy chamber, sammi min spec's work for a few rounds without separating the head! Remember, bumping the shoulder and partial sizing are the same thing. You will find some guy's like to partial size and still feel the shoulder rub a bit in the chamber closing the bolt. Most guy's size so the shoulder doesn't rub, easier closing the bolt with a hunting rifle.

One more thing, I always de-prime first trip through the die. Set the de-capping rod properly and you will eject the primer every time. Doesn't matter if your FL sizing or neck sizing with an FL die.

 

[WapitiBob]

Smoke the case shoulder and you'll know right when it touches.

 

[AlaskaHunter]

I deprime as the first step using the Lee Universal Decapping die, then clean cases to keep my dies clean.
I full length resize with a .002" shoulder bump without the decapper/expander stem in the sizing die.

The reason I remove the decapper/expander stem because I then use an expander mandrel for
better concentricity of the neck internal dimension compared to the conventional die expander stem.
Also expander mandrels push down, as opposed to pulling up with an expander ball or stem so less force on case shoulder...

 

[WapitiBob]

The problem with using a full length sizer to compress the necks, at least in my case, is the sizer compresses the neck .012” under bullet dia. At that, it’s no wonder necks work harden. I’m going to try a fl neck bushing die to compress the necks just under desired dia then use the expander to finish size. That should keep the id where it needs to be and neck thickness variants will be to the outside.

 

[schmalts]

Anyone use the Lee collet neck sizer on fire formed brass? I did that on a .243 and had great results.

 

[cowboy]

Look into getting a Redding Competition shell holder set (follow instructions it comes with), remove your firing pin from bolt for a better feel, and get rid of your expander ball in your die if you have a bushing die and you'll notice much more consistency in your reloads plus you'll be working your brass much much less

 

[Don Fischer]

I just got my first Lee collet die a year or so ago, for 243 also. Seem's to me to work fine but necessary to really push down hard on the press handle to get the neck where it need's to be. Otherwise you put a bullet in the neck and it just falls through. Something I really like about the collet die is the necks no longer stretch being pulled over the expander. Think I got another for my 30-06 with same thing. Never though about that when I first got them. In fact not eeven sure why I got them in the first place anymore.

 

[MT_Chad]

There seemed to be an overload of information and some debate about this on the net the last couple years. Some of the easiest to follow videos I saw were from a bench rest shooter, Eric Cortina (I think I got name right) and a guy from Long Range shooters. Seemed to make a lot of sense to me. All about getting more precise brass for a particular rifle, than producing a one size fits all rifles cartridge. Should be easy to find on Youtube. If not I can go back and find a link if you're interested.

Eric Cortina's videos are very good, I have learned a lot from his videos.

 

[MT_Chad]

Like @AlaskaHunter , I de-cap first as well to keep my dies clean. I don't find it to be that much more work and decapping dies are cheap.
Here is my process:
Decap
sonic clean
resize
tumble
final brass prep

I am far from an expert reloader and I don't do huge quantities, mostly just hunting and some target practice, but this process works well for me.

 

[cahunter805]

Curious for those of you using a decapping die. What do you mean “keep your dies clean”?
I use Redding sizing wax and clean my die after use. Never had a problem with a dirty die.

 

[cahunter805]

Look into getting a Redding Competition shell holder set (follow instructions it comes with), remove your firing pin from bolt for a better feel, and get rid of your expander ball in your die if you have a bushing die and you'll notice much more consistency in your reloads plus you'll be working your brass much much less

The Redding Bushing dies come with a smooth insert that you can switch out the expander ball for. Works great. I only use the expander for initially running new brass to straighten necks. After firing the smooth insert is all I use.