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case stretch in full length sizing die

My 308 Lapua brass stretches from fired length of 2.005 to 2.010 when run through my Redding FLS bushing die. The die touches the shell holder plus about 1/8 turn. Any less and the shoulder is not set back. The set back is around 0.001.

Just curious whether anyone using a similar die is getting the same amount of stretch, if not, then my paricular die might be a tad too long in the body.

My Redding neck die does not produce any stretch but tends to stay on the shelf for reloads used for 600yds + as I get 4 thou run out with it. Giving the bushing a slight amount of movement does not have any impact. Run out with the FLS die is <2 thou.

The brass is fired in a Barnard action with Krieger barrel. Fired cases are 0.340 diameter so the step down of 5 thou with a 0.335 bushing should be OK.

Appreciate any comments.
Martin
 
Well yes, your brass will "stretch" after a trip through the FL die.
Imagine your piece of brass as a sausage shaped bit of clay which you
roll between your hands, the sausage gets longer AND thinner ( I stole this
analogy from Glenn Zediker's book , Loading for Competition)
The FL squeezes your case evenly all round a thou. or so, the brass has to got
somewhere, inwards and lengthways. That's why brass should be trimmed to length
after FL sizing as all the cases should be the same. As your neck die is only sizing
a small portion of the cases overall length and stretch is almost immeasurable.
Hope this helps, I too Lapua shoot 308W brass but in a Predator action through a Lilja barrel.

cu, Chris
 
Thanks Chris,
Good analogy with the sausage. I do get pretty low run out with the FLS. Neck sizing is quicker, but at the cost of increased run out.
Martin
 
Martin in Aus. said:
Thanks Chris,
Good analogy with the sausage. I do get pretty low run out with the FLS. Neck sizing is quicker, but at the cost of increased run out.
Martin

Are you neck sizing with a bushing die or standard neck die? The advantage of a bushing die is that you work the brass less, and potentially minimize any runout effect.
 
Martin in Aus. said:
My 308 Lapua brass stretches from fired length of 2.005 to 2.010 when run through my Redding FLS bushing die. The die touches the shell holder plus about 1/8 turn. Any less and the shoulder is not set back. The set back is around 0.001. Appreciate any comments. Martin

Questions:

Did you remove the standard size "button" on the decapping rod?

Are you using just the decapping pin retainer?

If the button is still attached to the decapping rod, do you think it's possible ... that the "button" is defeating the purpose of the bushing(s) by running it up inside a neck (on the upstroke) that's been sized to the bushings dimensions (on the downstroke) ... and also stretching the neck by .005" (2.005" to 2.010")?

Something to think about ... if it hasn't been removed.

Try sizing without it and see what happens.

In Benchrest, most of us throw that darn thing (button) away. And, I can't think of a CUSTOM FL bushing die that's made with one.
 
yep, using the Redding FL with bush only I get the same issue...I can't remember the exact extra length but it would be close to .005...interestingly enough when I re-trim some of them the mouth is clearly longer on one side.
 
The neck die is a Redding bushing die and the complete decapping rod has been removed. The cases have almost zero run out when straight out of the chamber and the case necks are .340 diameter.

I have resized quite a few cases comparing the results from the Redding FLS die with the Redding NS die. The bushings are the same size 0.335 in each die. The run out is <2 thou FLS and around 4 thou when neck sized. With the neck die I have adjusted the locking screw to allow the bushing to float to allow the case neck to centre itself but there's no difference to run out whether the whole neck is sized or just half. The FLS die always produces cases with less run out.

Martin
 
Martin in Aus. said:
The run out is <2 thou FLS and around 4 thou when neck sized. The FLS die always produces cases with less run out. Martin

Suggestion: ONLY F/L SIZE ... and trim your brass when required.

In Brenchrest, that's what the majority of us do. If a person continuously neck sizes, eventually, you're going to have to F/L size or your case won't fit your chamber. So F/L size each and every time. Improved run-out right? You already proved that.

Set your die to push things down and in by .001" and you won't overwork your brass. A person only needs TWO dies: one to F/L size with bushing capability, and a bullet Seater. Keep life simple.
 
Martin,

the Forster Bushing-Bump die is a very good compromise for Target Rifle / F-Class type applications and cartridges like .223 Rem and .308 Win that have a fair degree of case taper. This die is a bushing neck-sizer that also adjusts the shoulder position as per a full-length die with the amount depending on how you set it up in the press. Unlike an FL die, it doesn't reduce the case-body diameter at all.

In my experience with these dies in both of the above cartridges (.308W in a Barnard P; .223R in a Savage PT action), I get virtually nil case-length growth only needing one trim if any over the life of the case (10 firings in .308W and 5 in .223R); chambering is easy and headspace tightly controlled with the shoulder 'bump' facility (set up to move the shoulder back 0.001" from that of the longest fired cases) despite using fairly stiff loads.

You still need an FL or body die to reduce the case body diameter if you start to experience difficult chambering or extraction, but I've never had to do this over two seasons of using these dies in .308W and one with .223R.

Laurie,
York, England
 
Laurie,

I held off purchasing a Forster bushing bump die being uncertain as to the advantage over their neck die (which I also have). It sounds like you're achieving more reloads per case with the Forster BB die before having to trim. You seem to be securing long intervals between full length sizing also.

What run out are you achieving ?

Thanks
Martin
 
A person only needs TWO dies: one to F/L size with bushing capability, and a bullet Seater. Keep life simple.
[/quote]

Good comments - but do you think 3 dies might be the minimum ? If you neck turn, the FLS bushing die does not allow you to get to the neck/shoulder junction to cut deep enough to prevent a dough nut (but not too deep as to weaken the case). I have an RCBS standard FLS die just for resizing new brass before it is neck turned. After that I use a bushing die for reloads of fired cases.

Martin
 
Martin in Aus. said:
A person only needs TWO dies: one to F/L size with bushing capability, and a bullet Seater. Keep life simple.
Good comments - but do you think 3 dies might be the minimum? If you neck turn, the FLS bushing die does not allow you to get to the neck/shoulder junction to cut deep enough to prevent a dough nut (but not too deep as to weaken the case). I have an RCBS standard FLS die just for resizing new brass before it is neck turned. After that I use a bushing die for reloads of fired cases. Martin

Again, TWO are all you need, here's why.

If I have to push a shoulder back on newly turned, unfired brass, to get it to seat in the chamber, I simply remove the bushing from the F/L bushing die!

Then, I push the shoulder back.

I replace the bushing before I F/L size reloads of fired cases.

ONE F/L die with bushing capability. Remove the bushing or leave it in place depending on what you're trying to do. One Seater die. Two in all.
 

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