Shoulder bumping question

[22BRGUY]

Have been reloading for quite awhile. I like to shoulder bump about 1 or 2 thou. After I set my FL die to bump the exact amount I choose, and then bump sometimes 5 or 6 cases. Suddenly the die set at the exact same place, same brass out of same rifle might either not bump quite enough or start bumping too much. After resetting the die again and bumping 5 or 6 more, again I may need to put it back to it's original setting or change it in another direction. Any of you experience this or have any suggestions on the cause?

Thanks all

 

[ridgeway]

How fast do you run the brass in and out of your die?

 

[22BRGUY]

Run it in and out very slowly and at the top of the stroke I always wait about 5 secs "dwell time" and then turn the case 90 degrees and do it again for straightness. Thanks for the question.

 

[SS427]

I'm having a similar problem sizing Lapua Fireball bass formed into .20 VarTarg. It doesn't seem to make sense.

 

[SET]

A lot has to do with how many times the brass has been fired. Some pieces of brass fired multiple times may achieve more "memory" quicker than others. I believe that's why many people anneal their brass more frequently now a days.
You might also feel a difference between pieces of brass when neck sizing and seating bullets. Some bullets seat with less force than others.

 

[BCoates]

If you are using a spray lube, I have seen the amount of shoulder bump vary because of different amounts of lube. Also, differences in case hardness and thickness can cause varying shoulder bump.

What ridgeway is alluding to is if you run the brass in and out of the die without pausing at the top of the stroke you can get varying shoulder setback. Best practice is to run the case up into the die allowing the press to cam over (if it has that capability) and then pause for a 5 count before retracting the case from the die.

 

[Erik Cortina]

What kind of press are you using?

 

[jonbearman]

I am with Chuck on the pause when sizing but it seems you might need to anneal to normalize the brass to its original state so the spring back is more predictable. I just annealed several thousand cases including some .223 I got from a member here and the shoulder set back is easily under a thousandth's as I size them. I only sized a few hundred but when I got to reload them the seating pressure was way nicer. No tough ones basically.

 

[Dave T]

I also switched from spray lub to RCBS lub with the lub pad and I seem to get a more consistent sizing and shoulder bump, what say you all?
Dave T

 

[artbosco]

Have been reloading for quite awhile. I like to shoulder bump about 1 or 2 thou. After I set my FL die to bump the exact amount I choose, and then bump sometimes 5 or 6 cases. Suddenly the die set at the exact same place, same brass out of same rifle might either not bump quite enough or start bumping too much. After resetting the die again and bumping 5 or 6 more, again I may need to put it back to it's original setting or change it in another direction. Any of you experience this or have any suggestions on the cause?

Thanks all

Some brass cases are softer than others. Leave the die set. Segregate the cases by the bumped amount. The excessive I use for foulers.

 

[ridgeway]

I also switched from spray lub to RCBS lub with the lub pad and I seem to get a more consistent sizing and shoulder bump, what say you all?
Dave T

Did you ever try Imperial sizing wax? Excellent stuff and one tin will last a LONG time.

 

[CatShooter]

Have been reloading for quite awhile. I like to shoulder bump about 1 or 2 thou. After I set my FL die to bump the exact amount I choose, and then bump sometimes 5 or 6 cases. Suddenly the die set at the exact same place, same brass out of same rifle might either not bump quite enough or start bumping too much. After resetting the die again and bumping 5 or 6 more, again I may need to put it back to it's original setting or change it in another direction. Any of you experience this or have any suggestions on the cause?

Thanks all

Are you using a true "Bump" die, or a FL or body die adjusted to nudge the shoulder??

 

[22BRGUY]

Using a Redding FL type S without bushing Cat on an older Pacific (now Hornady) 007 Erik

 

[BoydAllen]

Assuming that the amount of lube on each case is pretty much the same, and the dwell time at the top of the ram's travel is also, what you are seeing are differences in annealing and/or work hardening. To minimize these sorts of problems, I try to use my brass in batches that all have the same number of firings and FL sizing (more or less). Beyond that, if you can manage it so that your press toggles at the top of the sizing stroke, by use of Redding Competition shell holders, or a modified standard shell holder, that will make your results more uniform. The ultimate solution, if uniform use and number of sizing does not achieve your goal (or you are dealing with cases that are of mixed usage), is to anneal...carefully, and uniformly, after researching the subject thoroughly, and disregarding all of the old advice about glowing necks in darkened rooms. Ken Light would be a good name to Google for information.

 

[22BRGUY]

Thanks much Boyd. These cases are Lapua 6brs used for either 22brs or 6 dashers. Both seem to exhibit this oddity. I do pay close attention to keeping case batches separate form each other as to number of firings, reloads etc. even numbering each case to keep track of it's performance or lack thereof in comparison to the rest of the batch. All helpful info and food for thought and experiment guys and Thanks all again.

 

[Erik Cortina]

If I understand correctly, you are using a turret press? It so, is there any noticeable flex when you size brass?

Also, try not sizing the brass twice. Size a few pieces of brass without rotating them in the die and see if they are more consistent.

Last thing I would try is to replace lock ring on the die with a different one, preferably one with a clamp style locking ring rather than one that uses a set screw against die threads.

 

[22BRGUY]

Thanks Erik...the press is an older pretty heavy single stage but looking for "press flex" is a good thought. Also, I think I do have a couple Lee type lock rings...that makes sense also over the "tighten into threads" type.

 

[Syncrowave]

A lot has to do with how many times the brass has been fired. Some pieces of brass fired multiple times may achieve more "memory" quicker than others.

+1

If you have cases that have been fired more times mixed with cases that have been fired fewer times, the ones that have been fired more times will have been work-hardened more and will have more springback.

 

[TimP]

I had similar issues until I started annealing my brass. Now I can achieve a total of .0005 variance in length... Watch your die as well. I use a Harrells press and my die setting will loosen as I am running the press. I check the die tightness after each cycle.

 

[Barlow]

One trick I do is when I get a long one (.001-.003 or so) I cut a little paper shim and slide it under the case head on top of the shell holder and size it again to get it deeper without adjusting the die. I may get a feeler gauge set and cut them to fit. Works for shoulders and bullet seating, and I'm surprised at how accurate it is when you get the feel for it. Barlow