Question on setting up full length resizing die .308 Win.

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Hello, first time ever on this type of site, so be easy on me.

I am not new to reloading handgun ammo., but am new to rifle reloading, so here goes.
I have a .308 Win. Savage model 10, 24 inch barrel, 1 in 10 twist. As of this post I have only fired factory loaded ammunition and I am using the once fired brass to set up my press, Dillon RL550 B. I have also purchased 500 rounds of once fired LC LR brass, obviously fired in a different rifle.

I measured the brass fired in my rifle using Hornady case comparator tool on a dial caliper. They measure 3.727, relative measure given anvil and case comparator attached to caliper. From my reading I'm looking to size brass to 3.726 or there abouts? Please correct me if I'm wrong. I took great pains to adjust just so the length was right on the money. Tested brass in rifle chamber, works perfectly, no binding.

My problem lies with the LC LR brass. Most of those cases measure approx. 3.735, remember the attachments on caliper, measurements are relative to difference from start to finish. If I run them through the die as adjusted for the brass once fired in my rifle they only measure 3.729. Without changing the die adjustment if I run them through a second time they measure approximately 3.726 +. Being that running them through twice got me where I wanted to be I tried running the brass through the die twice in rapid secession, and the measurements were closer to the measurements after only putting them through once. I then took three pieces of brass and measured them after they went through the die each time, the longer time lag seemed to make a difference in the final measurement.

I want to do things right, but I wouldn't mind skipping a step if it's not detrimental to the process. I "ASSUME" the problem lies with the starting size difference between the one fired brass fire formed in my rifle vs. the longer case size of my purchased once fired brass. That being said would I be better off resetting the die so the desired size is reached with one cycle of the press for the LC LR brass? Then resetting the die after the brass has been fired formed to my rifle? Or should I leave it adjusted where it is and run in through twice?

I did note that unlubricated brass does not change dimensions the same as lubricated brass. This happened accidentally after dropping a lubricated brass, which had been through the sizing die once, on the floor and wiping it clean, then forgetting to reapply lube to that one case. No matter how many times I put it through the die dimensions didn't seem to change much. I then lubed the case and the correct length was obtained.

Please help me with some words of wisdom, or encouragement.

Thank you for your posts on this site, I read many before starting, but quickly ran into an unforeseen problem.
 
I'm confused. what you are measuring?

308 win. Case trim to length is 2.005" and COAL is 2.800" about.

I've been reloading 308 for a few years for shooting 1000 yards.

I full length size all my brass and check for cracks and measure length and have never had a problem.

Still wonder what your measuring.
 
I'd be full length sizing that brass not fired in your gun for sure, all the all to the shell holder. Then trim to length, champher & debur. After that check and see how the empty case fits in your chamber.

The next important step is to figure out how long you want the COL. I use a measure of sorts with each type of bullet, to get distance to the 'lands'.
 
I think what he is asking is why does it take two times of FL resizing to get te LC brass to size to the length he wants. If this is the question, then here is one answer. Each different case will have more or less spring back. Being that LC is thicker than most other companies it would make since that it would take either readjusting your die or sizing twice to get your results.
 
I think what he is asking is why does it take two times of FL resizing to get te LC brass to size to the length he wants. QUOTE]


That's what I think but his numbers are way off to be 308win Case length.

He is massuring with his bumb gague comparator. I bet he got his terms mixed up. It's not the case length, he is just just trying to set up his die to bump his case.
 
I think what he is asking is why does it take two times of FL resizing to get te LC brass to size to the length he wants. QUOTE]


That's what I think but his numbers are way off to be 308win Case length.

He is attaching some sort of comparator to his calipers, and measurements he is providing include the length of that comparator.
 
Sorry if I confused anyone.

I have attached a Hornady lock n load cartridge headspace gauge bushing to one side of my caliper and a Hornady anvil base to the other side. With both tools attached zero the caliper ends up at an inconvenient measurement, to convert quickly, and I was in a rush to get to work. I did zero the caliper but I was solely using the difference in the two measurement as the comparison. For instance bumping the case back .001, which I believe is correct?

Was mostly looking for answer to sizing the LC LR brass.
 
Firearrow is correct! Is running the brass through the die twice harmful to the brass?

If only the headspace gauge was attached it would be a matter of subtracting 2" from total measurement to obtain the actual headspace measurement, but at the last minute I attached the anvil and I was unsure at the time of the post how much length that added, so I just used the total measure for comparison.

I'm taking baby steps, but plan on taking all necessary measurements before loading the first bullet. Then comes the testing phase and tweaking to obtain the best results.

Don't want to make 500 mistakes!
 
No, don't make 500 'mistakes', if any just 10 or so.

If properly lubed, I see no problem with running a case more than once through a sizing die. When I have done it, I usually spin the case. That's just to give it different orientation in the die.
 
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