Sizing Cases

antelopedundee

antelopedundee

internet bum
When sizing cases [neck or FL] do you run the case into the die and quickly pull it out or do you let it linger in the die with the idea that the longer it lingers the less likely the brass is to try to spring back to it's pre-size dimension?
 
I do it at a moderate speed, because I'm verging on elderly and I MOVE at a moderate speed.

AND, because my loads don't shoot as well with bloody hunks of my fingertips inside.

I don't believe the brass knows from "dwell."
 
There are several variables that come into play when FL sizing. To the degree that your brass has some spring back, dwell matters, as does the amount of lube. Of course the type of lube is a factor in that some times do not have the heavy lube potential that others do. If you rotate strictly within a given set of brass, and use the same amount of lube, and the same stroke, your results will be more consistent, but even if you do those things, depending on the brass, you can see more runout in bump than you may want. Careful annealing can solve this problem, and looking at bump consistency can aid in evaluating annealing dwell time. These are easy experiments to do. I did them a long time ago. Dwell time also applies to expanding for turning, with the additional observation that there is some snap back after expanding that is time related. I first noticed this when my cordless screwdriver battery quit, leaving me with some cases that were expanded that I got back to a day or two later. They ended up being tighter on the turning mandrel than the ones that were turned immediately after expanding. This was no big deal since I had left the lube in the cases (the ones that I waited to turn) only requiring running them over the expander again.
 
Boyd Allen said:
There are several variables that come into play when FL sizing. To the degree that your brass has some spring back, dwell matters, as does the amount of lube. Of course the type of lube is a factor in that some times do not have the heavy lube potential that others do. If you rotate strictly within a given set of brass, and use the same amount of lube, and the same stroke, your results will be more consistent, but even if you do those things, depending on the brass, you can see more runout in bump than you may want. Careful annealing can solve this problem, and looking at bump consistency can aid in evaluating annealing dwell time. These are easy experiments to do. I did them a long time ago. Dwell time also applies to expanding for turning, with the additional observation that there is some snap back after expanding that is time related. I first noticed this when my cordless screwdriver battery quit, leaving me with some cases that were expanded that I got back to a day or two later. They ended up being tighter on the turning mandrel than the ones that were turned immediately after expanding. This was no big deal since I had left the lube in the cases (the ones that I waited to turn) only requiring running them over the expander again.
Click to expand...

Does starting neck thickness have any bearing on the situation? Last year I acquired a quantity of PPU brass in .270 and .25-06. I used the .270 cases to make into 6.5-06 cases to avoid any identity issues which might arise from simply necking up the .25-06 case. I also purchased a box of the Nosler .25-06 premium cases. This year I acquired some Norma .25-06 cases and a 20 pack of the Quality Cartridge 6.5-06 cases. Deciding that I would neck turn everything, I purchased 2 of the Sinclair NT-1000 cutters and carbide mandrels for .25 and .26 caliber. Tried to set both cutters to leave the necks at about .012 thickness.

The QC cases turned pretty nicely after expanding with the .263 mandrel. Worked smoothly with most of the neck being cleaned up.

I set half of the Norma cases aside to convert to 6.5-06. These turned with some difficulty in both .25 and .26 size while leaving brass stains on the mandrel. There was for the most part 100% removal of brass. Got similar results with a few of the nosler cases.

There was no problem with tight fit for the PPU cases. Thing is the amount of clean up was pretty variable with almost no removal except at the neck-shoulder junction to not quite 100%. Probly got enough brass to last till I croak, but if I ever get more Norma I'd probly not waste time turning it.
 
This happens to me. And it is the reason I now have a dedicated press for each chambering/die setup.

If I'm shooting a single chambering for days I will often have the die settings honed to such perfection that clearances are nearly .0000 but my bolt is still falling closed. I can literally shoot the same 5 cases for days, 20-40-100times while experimenting and then, if I leave them loaded up and set the project aside for a month......

The same loaded rounds offer complete refusal :)

ie they won't even let the bolt close.
 
I heard about this several years ago, tried to get into a Rhythm of allowing each case to dwell in the die for about 5 seconds.

As with most new ideas, I used my Rail Gun to see if there was any worth to it. Load 5, letting the case dwell in the die, 5 with just the usual up and down in a second.

I could’t Tell the difference. Maybe it’s something, like a lot of things that are a necessity at longer ranges but don’t seem to matter in 100/200 yard Benchrest.
 
Jackie,
Did you compare the bump that you got, with the same die setting, and cases that had been shot a similar number of times, no dwell to dwell? I am not saying that one would be more accurate, just the amount of bump on a springy case would vary, with the longer dwell causing slightly more bump.
 
Boyd Allen said:
Jackie,
Did you compare the bump that you got, with the same die setting, and cases that had been shot a similar number of times, no dwell to dwell? I am not saying that one would be more accurate, just the amount of bump on a springy case would vary, with the longer dwell causing slightly more bump.
Click to expand...

Boyd, I have always been pretty aggressive with sizing, hitting the shoulder so I have about .002 bump. I have also modified my Dies through the years to where it hits the case body pretty aggresivly as well.

With my 30 BR, I will pre load for a match with 90 cases, starting with a box with many fired as many as 20 times. After sizing, I cycle each case through the Rifle, discarding any that do no feel right. As you stated, the culprit is usually the shoulder, it does not want to stay "bumped" so to speak.

If, during a match, I feel a round go in tighter than the others, it gets dumped on the sighter.

So I am segregating cases as I go. Some just seem to last longer than others.

As I said before, a lot of the things we do in short range do not carry over in long range. Velocity spread is the big one. I have shot 10 shot groups in the teens with a velocity spread on 25+ fps. That much spread would be useless in a 600 yard+ rig, where ES and SD seem to be the most important criteria in load development.
 
alinwa said:
This happens to me. And it is the reason I now have a dedicated press for each chambering/die setup.

If I'm shooting a single chambering for days I will often have the die settings honed to such perfection that clearances are nearly .0000 but my bolt is still falling closed. I can literally shoot the same 5 cases for days, 20-40-100times while experimenting and then, if I leave them loaded up and set the project aside for a month......

The same loaded rounds offer complete refusal :)

ie they won't even let the bolt close.
Click to expand...

Can you pull the bullets out by hand for the ones the bolt won't close on?
 
But Jackie...

jackie schmidt said:
I heard about this several years ago, tried to get into a Rhythm of allowing each case to dwell in the die for about 5 seconds.

As with most new ideas, I used my Rail Gun to see if there was any worth to it. Load 5, letting the case dwell in the die, 5 with just the usual up and down in a second.

I could’t Tell the difference. Maybe it’s something, like a lot of things that are a necessity at longer ranges but don’t seem to matter in 100/200 yard Benchrest.
Click to expand...

You're forgetting the super precision of your RCBS Partner presses!
 
antelopedundee said:
Can you pull the bullets out by hand for the ones the bolt won't close on?
Click to expand...

No.

But I shoot fitted necks with VLD's. I can't pull the bullet on a just-fired case.

For PPC's I run enough clearance that bullets are just a light slip-fit in a just-fired round, and I size them down several thou upon reloading (for 133) but no, no matter what the necks don't relax enough to be noticeable. To me.
 
You must log in or register to reply here.
Back
Top