Body Sizing Variation...Why??

[Reload10]

Hoping someone can help me out. I have been using a batch of LC11 308 cases sorted by 1 grain extreme spread by weight. Did every prep step to them but neck turned.

I sized in a RCBS FL die initially when purchased, and now I use a Redding Body Die and a Lee collet die.

I've noticed that every now and then I'll get a case that doesn't have the shoulder pushed back as far as others. IE I strive for 1.622"-1.624", and every now and then I'll get one at 1.628"-1.630". I know I'm being as consistent as possible with lube and press arm pressure.

Is this enough variation to worry about? If it is, what steps should I take to try and reduce headspace variation? I've been doing a lot of practice at 600 yards and want to reduce as much variation as possible.

Thanks for the input!

 

[243winxb]

Is the shell holder contacting the botton of the body die at the top of the stroke?

If not, try these. https://www.midwayusa.com/product/525874/redding-competition-shellholder-set-1-308-winchester-30-06-springfield-45-acp

 

[bigedp51]

If your Lake City cases are once fired military brass they were fired in a longer and fatter chamber. So now you are dealing with brass spring back after sizing, meaning the cases are trying to spring back to their fired size.

Try sizing the cases and pausing at the top of the ram stroke for 4-5 seconds, this reduces brass spring back.

Right now I'm sizing once fired Lake City 7.62 cases using a small base .308 die that reduces the body diameter to SAAMI minimum diameter. The small base dies also sets the shoulder back .002 to .003 more than a standard die.

And as linked above you can use the Redding competition shell holder to control shoulder bump.
​

 

[dok7mm]

Inconsistent shoulder bump is an indicator of work hardening. Sounds like you may need to anneal, to get back to uniform resizing. I am assuming your die setting, lube, etc. are correct.

 

[Reload10]

Is the shell holder contacting the botton of the body die at the top of the stroke?

If not, try these. https://www.midwayusa.com/product/525874/redding-competition-shellholder-set-1-308-winchester-30-06-springfield-45-acp

Thank You. It is not, I can top out the ram with a piece of paper on the shell holder, and it pulls out with little resistance. Might have to pick those shell holders up, would be able to use them for 3 of my cartridges.

If your Lake City cases are once fired military brass they were fired in a longer and fatter chamber. So now you are dealing with brass spring back after sizing, meaning the cases are trying to spring back to their fired size.

Try sizing the cases and pausing at the top of the ram stroke for 4-5 seconds, this reduces brass spring back.

Right now I'm sizing once fired Lake City 7.62 cases using a small base .308 die that reduces the body diameter to SAAMI minimum diameter. The small base dies also sets the shoulder back .002 to .003 more than a standard die.

And as linked above you can use the Redding competition shell holder to control shoulder bump.
​

Thanks! Didn't think of that...I might as well anneal them all after firing (this will be 3x fired).

Inconsistent shoulder bump is an indicator of work hardening. Sounds like you may need to anneal, to get back to uniform resizing. I am assuming your die setting, lube, etc. are correct.

Thank you. I'll anneal and re-evaluate. Die setting is correct, and I first use a spray lube on the lot of cases, then I use sizing wax on my gloves and rub the cases before going on the press. They size very effortlessly.

 

[Lonewolf74]

Does the die need to touch or bottom out on the shell holder to be set correctly or be the most consistent? I have a dillon 550 and my sizing die is set to where it bumps the shoulder back .003 and it seems to work good but I do sometimes see a .003 variance from case to case. But even setting it up to factory specs the die still wouldn't touch the shell holder, I think it's stated to not set the die that way for the dillon.

 

[bigedp51]

Depending if you have any flex in your press and brass spring back your shoulder location can vary. I buy a lot of once fired Lake City brass fired in a variety of chambers so I make sure the die makes hard contact with the shell holder.

This is where having Redding competition shell holders to control shoulder bump are nice to have. I also pause 4 seconds at the top of the ram stroke then rotate the case 180 and size a second time and this greatly reduces brass spring back. Meaning more constant shoulder location and cartridge case headspace length.

Right now I'm sizing Lake City 7.62 machine gun brass and the above method works well for more uniform shoulder location. Also your cases might be telling you they need annealed.

 

[Pdvdh]

Depending if you have any flex in your press and brass spring back your shoulder location can vary. I buy a lot of once fired Lake City brass fired in a variety of chambers so I make sure the die makes hard contact with the shell holder.

This is where having Redding competition shell holders to control shoulder bump are nice to have. I also pause 4 seconds at the top of the ram stroke then rotate the case 180 and size a second time and this greatly reduces brass spring back. Meaning more constant shoulder location and cartridge case headspace length.

Right now I'm sizing Lake City 7.62 machine gun brass and the above method works well for more uniform shoulder location. Also your cases might be telling you they need annealed.

10-4. Agree with your explanations of the source(s) (causes) of the problem, and the corrective measures. I use them myself.

Any case that imposes additional force on the press handle, rotate 180* and size again. I can generally identify a casing that ends up under-sized by the additional force required on my RCBS Rockchucker press. I check headspace on those cases, one by one, after resizing them. If still too long, I set them aside for an additional sizing step through my resizing die. There are a number of means and methods to obtain additional shoulder setback with your resizing die. Some have already been identified. Some require more fussing and time than others.

 

[bigedp51]

"Some" reloaders use feeler gauges between the die and shell holder to adjust shoulder bump. "BUT" this leaves a air space between the die and shell holder and any flex in the press can effect shoulder bump.

My Rockchucker press is 44 years old and a little worn, so by using Redding competition shell holders my dies always make hard contact with the shell holder and the press cams over. And all I need to do to adjust shoulder bump is change shell holders and never touch the die. And any slop in the press is removed and the press has no effect shoulder bump.

 

[Reload10]

Update:

After annealing, then sizing the brass and holding the ram at the top of the stroke for ~3 seconds, the headspace is very consistent.

Thanks for the help!