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head space 223 rem. fired vs full length sized

I'm using a Lee full length sizing die, and a hornady caliper and hornady head space gauge, and the correct #330 insert. I'm shooting a Stag AR-15 with standard 20" barrel. When I measure the difference between fired brass and full length sized brass, there is a difference of 13 thousands. Is that an extreme number, or is that normal ?
 
That's way too much bump.

.002-.003 is plenty.

I try for no more than .001" on my bolt guns.
 
After reading a little about head space, it sounds like I have a safety problem with the brass I have full length size to have excessive headspace. The problem is I've sized about 400 brass at this length. Is it going to be dangerous for me to shoot this brass one time to get it back to a length where I can size it with the correct headspace ? Most of this brass is once fired brass, but there are about 75 of them that I have fired twice.
 
Personally, I would dispose of the brass. You may encounter misfires due the firing pin not dimpling the primer enough to cause ignition. I typically bump the shoulder .003 to .005 for my gas guns when reloading fired brass. I have found that the RCBS Precision Mic is the most accurate gauge when checking headspace for gas guns.
 
I can't say whether or not this will apply to your AR, but I just experimented with a Garand to test the headspace. I removed the front gas plug and single shot some rounds to get a headspace measurement, then semi-auto fired some rounds. I did this because the measurements for fired semi-auto where all over the place--how was I supposed to set the die if I wanted to resize close to actual headspace?

The single shot headspace measurements were within .001-.002 of each other, and the semi-auto rounds were from .005-.012 longer than the single shot--so maybe the brass hadn't stopped expanding when extraction started in semi-auto, but obviously not consistantly.

I have also on occasion picked up a box of factory ammo to check headspace and point of impact to compare to reloads. Are your reloads hot(ter)?

Is it possible to disconnect the gas system while still having a locked bolt for single fire in an AR? You might try this IF POSSIBLE to see if you can get a better ideas of what the measurements are. The bolt MUST be locked when fired.
 
My fired brass headspace measurements are within .001 of each other, so I don't have a problem knowing what to use as a fired measurement. Last night I got to adjust my die so it set the shoulder back .002 from the fired brass. I haven't tried it yet today, but I wonder if I take the brass that I have full length size to the excessive headspace and full length resize them with the die set at the proper headspace, will it move the shoulder forward a little ? I'm hoping that I don't have to throw away all that brass that I've spent hours prepping. As far as disconnecting the gas system, I don't have the knowledge or the tools to do that.
 
Junk the brass. It's not worth piercing a primer or separating a case head to save a few bucks.

You probably won't be able to bump the shoulder back by resizing again.
 
I'd junk the brass, and here is why....


When my dad passed 10 years ago, all his reloading gear came to me, including a couple thousand pieces of Lake City .223 brass. When I finally got around to using the brass, I did not check the bump, and all were sized too short, as you described. I learned this because I put together a quick 100 of a good known and safe load for this rifle.

Immediately, when I was rezeroing the rifle, I noticed really crazy pressure signs...super flat primers, as well as light hits that would not ignite. Shot 4 would not chamber, because 30 percent of shot 3's separated case was lodged in the chamber. On further inspection, all the cases were on the verge of separation.

After 5 shots I finally stopped. Later, when I finally figured out the issue, I realized I had a lot of bullets to pull. I made the wrong assumption that my dear old dad had his dies set up correctly...they probably were correct for his chamber, but in mine the results were not cool.

Wear safety glasses, live, and learn.

MQ1
 
Rather than trashing your brass, I'd neck them up to 6mm, then back down to 22 in the die, now that you have it set at .002" bump. I'll form a secondary shoulder to headspace on, (like forming Dashers) and hold the brass and stop/slow down the potential problems at the web.
 
alf said:
Rather than trashing your brass, I'd neck them up to 6mm, then back down to 22 in the die, now that you have it set at .002" bump. I'll form a secondary shoulder to headspace on, (like forming Dashers) and hold the brass and stop/slow down the potential problems at the web.

Alf, I don't have the die and the bushing to neck up to 6mm. By the time I buy them, I could buy once fired brass. It sounds like most people think it's enough of a safety problem, that I should trash the brass and start over.
 
Alf is right on about necking it up and making a false shoulder. If you don't have the stuff to do it today, put them in a clearly marked bag until you can borrow or buy the mandrel and die to neck up to 6mm.
 
When I measure the difference between fired brass and full length sized brass, there is a difference of 13 thousands. Is that an extreme number, or is that normal ?

Next time start by measuring the length of the new unfired case from the head of the case and shoulder, the difference between new-unfired and fired case length will give you the effect the chamber had on the case.

After determining the the case has stretched .013” you can adjust the die to size the fired case by adjusting the gap between the bottom of the die and top of the shell holder, after making a wild guess, you can verify the gap with a feeler gage, I would not go for the whole .013”. I would start by reducing the gap to .010”, then check to see if the case will chamber.

F. Guffey
 
The problem was he pushed the shoulders back .013" from the fired dimension.

New brass length is irrelevant.
 
Why can't he just reduce his powder load to reduce pressure, use a lighter bullet and refire-form the brass to his rifle?
 
RStewart said:
Why can't he just reduce his powder load to reduce pressure, use a lighter bullet and refire-form the brass to his rifle?

RStewart, I was wondering that myself. I have H322 and H335 powder and 55 gr and 60 gr bullets. What charge would be safe, yet still fire form the brass ?
 
short range said:
RStewart said:
Why can't he just reduce his powder load to reduce pressure, use a lighter bullet and refire-form the brass to his rifle?

RStewart, I was wondering that myself. I have H322 and H335 powder and 55 gr and 60 gr bullets. What charge would be safe, yet still fire form the brass ?

What load are you currently shooting? Powder, charge and bullet.
 
RStewart said:
short range said:
RStewart said:
Why can't he just reduce his powder load to reduce pressure, use a lighter bullet and refire-form the brass to his rifle?

RStewart, I was wondering that myself. I have H322 and H335 powder and 55 gr and 60 gr bullets. What charge would be safe, yet still fire form the brass ?

What load are you currently shooting? Powder, charge and bullet.

RStewart, I'm shooting hornady 55 gr spire point and H335 23.7 gr Lake City brass, PMC brass
 
short range said:
RStewart said:
short range said:
RStewart said:
Why can't he just reduce his powder load to reduce pressure, use a lighter bullet and refire-form the brass to his rifle?

RStewart, I was wondering that myself. I have H322 and H335 powder and 55 gr and 60 gr bullets. What charge would be safe, yet still fire form the brass ?

What load are you currently shooting? Powder, charge and bullet.

RStewart, I'm shooting hornady 55 gr spire point and H335 23.7 gr Lake City brass, PMC brass

I only throw this out, because factory loaded ammo is able to be used in all kinds rifles with different headspaces. I would back off 1 grain of powder. You're not worried about accuracy, just getting the bullet out of the barrel. Try with one round first.
Also, see if you can measure the headspace on a factory load and see how that compares to your fired round.
 
Factory loaded ammo is built to spec, and is designed to be shot in rifles correctly headspaced.

If you choose to move ahead...expect backed out primers, primers that don't go off because the round is free to move in the chamber, and depending on the brass you are using...separated cases.

I already explained how I learned this the hard way...

MQ1
 

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