problem bumping shoulder back

[dmax1800]

I'm having a problem that I haven't had before and I have loaded only about 1200 rifle rounds. I'm trying to bump the shoulder back 2 thou with a FL sizing die. I can only get it bumped back 1 thou. The cartridge is 300 win mag, RCBS FL sizing die, Lee press, RCBS shell holder. Normally I can bump the shoulder back as much as I want to : 2 to 5 thou. I've tried resetting the die until it just touches the shell holder with the ram all the way up and then rotating the die 1/16 to 1/8 turns at a time after sizing a cartridge. Still will only bump the shoulder back 1 thou. I've gone 3/8 of a turn and the ram won't hardly cam over, but still only 1 thou of shoulder bump. I've tried several different cartridges and still only 1 thou.
Maybe I'm doing something dumb, but I don't know what it is.
HELP!
Thanks.

 

[supercrossbmx69]

Your either going to have to shave down the bottom of your sizing die or shave a little off the top of your shell holder.

 

[Mikecr]

Try going the opposite way & backing off on the die. Too much body sizing can push shoulders forward.

 

[theEMP]

Did this problem just start or has it been like this all along? I have also noticed that with my RCBS die it has a hard time doing a good bump. So I'll be following this thread.

 

[dragman]

Redding makes a shell holder set that gives you the different heights to bump the shoulder more or less. I would try them before cutting on die or shell holder.

 

[dmax1800]

Did this problem just start or has it been like this all along? I have also noticed that with my RCBS die it has a hard time doing a good bump. So I'll be following this thread.

This just started last night for the first time. I have never had this problem before. Before I could bump the shoulder 2 to 4 thou without going past 1/4 turn after the die touched the shell holder. I have since tried 2 other shell holders; another RCBS and a Lee shell holder. All 3 did exactly the same. I measured the distance from where the cartridge base sits to the top of the rim. All 3 measured EXACTLY the same. I thoroughly cleaned all 3 and no effect. I tried a different press, a Hornady, and it did the same. So I've tried different shell holders and a different press.
Now what???

 

[Mikecr]

Now what???

Did you try backing off on your adjustment?

Just a theory;
Take the die down to just kissing the shell holder, then back it off 3/4 of a turn. Lube a case, size it, dry it, feel the chambering of it with the firing pin/spring removed. If you feel resistance adjust down no more than 1/8 of a turn & repeat this cycle until you're just clear of chambering resistance.
Don't tighten the die until sneaking up on a good bump, then back it off a smidge and tighten locked ring with a wrench.
Trial & error(measure)

With careful comparison measurement(depending on shoulder angle), this should put you 1-2thou of head space, which is plenty.
Some FL dies adjusted to shell holder as a 'standard', would set back shoulders enough for ammo to fit in ANY SAAMI chamber. But this could be too much for your chamber(excessive), and shorten case life.
While you had 4thou it was too much IMO. So adjusting downward from there seems counter productive.

 

[SidecarFlip]

Additionally, it's easy to remove a couple thousands from the base of the die even manually by carefully grinding the base preferrably on a flat abrasive belt, or for a couple bucks, take the die body to any machine shop and have them chuck it a collet on a surface grinder and grind a couple thousands off.

Whatever way you do it, be sure to clean the body carefully with brake cleaner and blow out with compressed air before using to get the swarf and grit out.

I have a ultra precision surface grinder and I believe I've wacked off at least 0.001 on all my dies with the exception of my Whidden's because John Whidden has already done that to his.

As an aside, you can also grind the engagement face of any shellholder a couple thousands, problem is, fixturing the shellholder and keeping it square and parallel. The only way I know to do that is on a surface grinder because the shellholder is case hardened and do it must be ground. A couple thousands won't compromise the hardened surface. Typical cased steel is hardened 0.015.

 

[kraky2]

I hate camming over the press...I have several shaved shellholders that allow me full accurate control of head space.
Shave about .010" off one and don't look back!

 

[dmax1800]

Did you try backing off on your adjustment?

Just a theory;
Take the die down to just kissing the shell holder, then back it off 3/4 of a turn. Lube a case, size it, dry it, feel the chambering of it with the firing pin/spring removed. If you feel resistance adjust down no more than 1/8 of a turn & repeat this cycle until you're just clear of chambering resistance.
Don't tighten the die until sneaking up on a good bump, then back it off a smidge and tighten locked ring with a wrench.
Trial & error(measure)

I tried as you suggested, but measured with a head space gauge each time. I also removed the expander stem to eliminate the possibility that it was pulling the shoulder back out. I started at 3/4 turn off kissing and sized, measured and turned 1/8 turn until I was 1/4 turn past kissing. I found that right at kissing I could get 2 thou of shoulder bump. But when I put the expander stem back in, it reverted back to getting only 1 thou. I have already polished the expander ball and it is still shiny, smooth and no crud.

I also tried a 270 win RCBS FL die on fire formed brass with 1/4 past kissing. It wouldn't bump the shoulder at all. I tried a 22-250 RCBS die on fire formed brass at 1/4 turn past kissing and got 5 thou of bump.

So 2 FL dies don't bump the shoulder and 1 does on the same press.
I think I will try annealing a few of the 300 brass to see if they have hardened and spring back too much. Beyond that, I'm stumped.

Thanks for all the replies and keep them coming. I'm dependent on you guys for some help.

 

[dmax1800]

I think I have found the problem. lightbulb I annealed 3 cases, immediately quenched them in water, dried them off, lubed them, measured from the base to the datum, resized them and then measured them again. Even with the die just touching the shell holder with the ram all the way up, I got 4 to 5 thou of shoulder bump.

It has been probably 5 months since they were last annealed. Some of the brass were reloaded 3 months ago and didn't have a problem. Apparently they hardened in that short time. I would never have guessed that they would harden in that period of time.

Guess I'll have to anneal them before trying to resize them.

Should I wait a few days after annealing them before resizing them?

 

[Mikecr]

Glad you figured it out.
Hopefully you're not excessively sizing to cause work hardening.
Have you needed much trimming with these?
What's the cartridge?

 

[dmax1800]

Mike,
I don't think they were work hardened, just age hardened since the last annealing.
I just trimmed about 3 to 5 thou off of some to get them all within about 5 thou of each other. I'll let the short ones grow. So no, I didn't have to trim much.
Its a 300 win mag, so with a short case mouth already, I don't want to trim any more than I absolutely have to in order to keep them fairly close.

 

[Mikecr]

Never heard of age hardening, but it sounds like something did harden them(my belief is cycles of excess sizing).
Anyway, if you have to anneal shoulders to get them to take a bump, you have a problem to find & fix.