strange problem when sizing

[rebs]

I am resizing 223 brass with an RCBS sizing die. Out of 40 brass sized I get 37 that are sized right and 3 that the shoulder is bumped back .004 too much and they won't fire because the case moves forward in the chamber causing a light primer strike. What would cause 3 out of 40 cases to be bumped back too much? The press is a Hornady LNL progressive press.

 

[jepp2]

3 that the shoulder is bumped back .0004

0.0004 or 0.004? How are you measuring case head to datum? What did they measure before sizing? How much short of bolt contact are you sizing to?

I've never seen 0.004" shorter cause failure to fire. FP protrusion is normally about 0.050" What do the primers look like after the strike?

 

[K22]

Do you mean .004?

What brand of brass?

Was the brass virgin to start and did you fire form before bumping the shoulder?

You said 47 are sized right - what does that mean dimensionally?

Bolt rifle or semi?

You may not need to bump the shoulder at this point, but more info needed to make an intelligent suggestion.

 

[joshb]

You obviously have a math problem!

 

[rebs]

Do you mean .004?

What brand of brass?

Was the brass virgin to start and did you fire form before bumping the shoulder?

You said 47 are sized right - what does that mean dimensionally?

Bolt rifle or semi?

You may not need to bump the shoulder at this point, but more info needed to make an intelligent suggestion.

yes I meant .004 yes it was virgin LC 18. I did not fire form. 37 pieces are 1.460 and 3 pieces are .453 bolt rifle

 

[markm87]

Even a .004" over-squeeze should still fire. It might give a case separation though. I'd be more concerned with the rifle perhaps.

 

[rebs]

0.0004 or 0.004? How are you measuring case head to datum? What did they measure before sizing? How much short of bolt contact are you sizing to?

I've never seen 0.004" shorter cause failure to fire. FP protrusion is normally about 0.050" What do the primers look like after the strike?

I am measuring case head to shoulder. The primers look like a light strike.

 

[rebs]

Even a .004" over-squeeze should still fire. It might give a case separation though. I'd be more concerned with the rifle perhaps.

the ones that did not fire are about .007

 

[Pawnee Bill]

Why are you FL sizing virgin brass?

 

[Eagle Six]

Reviewing what I think you have said....

Out of 50, 47 are normal (.003" shoulder bump) and fire fine. Out of the 50, 3 did not fire, perhaps caused by a lite firing pin due that the shoulder bump is .007".......is that all correct?

Can you post some photos, head, should, neck comparison of one fired and one misfired?

 

[rebs]

Reviewing what I think you have said....

Out of 50, 47 are normal (.003" shoulder bump) and fire fine. Out of the 50, 3 did not fire, perhaps caused by a lite firing pin due that the shoulder bump is .007".......is that all correct?

Can you post some photos, head, should, neck comparison of one fired and one misfired?

yes that is correct.

 

[rebs]

Why are you FL sizing virgin brass?

to set the neck tension, I thought it was necessary.
Is it not necessary to FL size virgin brass?

 

[Eagle Six]

A couple more questions...

Where are you getting virgin LC18 brass from? Is this virgin or once fired?

Do you have any of this brass that you have not sized yet? If so, what do they measure?

How to you know it was your sizing that pushed the shoulder to .007"?

 

[gdbleb]

Are you loading "progressively" or single stage mode on the LnL press? Reason is the flex is different so if you are progressive the initial cases and/or the ending cases may have different shoulder setback.
I had this when trying it on a Dillon 550 and it has been written about here.

What do the "good" cases measure after firing? That should determine your setback going forward.

 

[rebs]

A couple more questions...

Where are you getting virgin LC18 brass from? Is this virgin or once fired?

Do you have any of this brass that you have not sized yet? If so, what do they measure?

How to you know it was your sizing that pushed the shoulder to .007"?

I got it from Graf's a few years ago. I don't know that is what I am trying to figure out, maybe some of the virgin cases came with the shoulder bumped too far back

 

[rebs]

Are you loading "progressively" or single stage mode on the LnL press? Reason is the flex is different so if you are progressive the initial cases and/or the ending cases may have different shoulder setback.
I had this when trying it on a Dillon 550 and it has been written about here.

What do the "good" cases measure after firing? That should determine your setback going forward.

The cases that fired are setback 1.460

 

[Webster]

I am resizing 223 brass with an RCBS sizing die. Out of 40 brass sized I get 47 that are sized right and 3 that the shoulder is bumped back .004 too much and they won't fire because the case moves forward in the chamber causing a light primer strike. What would cause 3 out of 40 cases to be bumped back too much? The press is a Hornady LNL progressive press.

Are you seating the primers to the bottom of the pocket? The only time I had a misfire was when seating to a certain depth and not the bottom of the pocket. New loaded factory brass probably has a very large space between the case and chamber shoulder and it still fires.

 

[Pawnee Bill]

to set the neck tension, I thought it was necessary.

On virgin brass, most of us just run them through a mandrel to ensure the necks are straight, then load & shoot. Full length & set the shoulder after fire forming.

 

[chromatica]

Are you pulling an expander ball through the case necks? If so, this action can pull the shoulder out of true.

 

[Coyotefurharvester]

I have a bulk box of new '09' lake city most run 1.4565 with my Hornady comparator. I set my die to size 1.460 most of a batch of mixed HS brass(hornady one shot lube) will run 1.4585-1.460, occasionally one will be pushed back to 1.457. I have not had any separation issues, I don't load to max data charge weight. I FL size without expander/decap rod. With my die set, I use the brass in 2 AR, 2 bolt guns. Mostly hunting rds, and prairie dog loads. I have not seen 0.007 variations. Run a batch setup to target size without the expander, see if more consistent.