will neck sizing vs fl sizing affect headspace ?

[Countryboy1150]

Why I ask is.... I have 25 rounds that have been fire formed to my chamber now. I neck sized them only this time around. Will that change headspace
(which I think it does ) and if so how will that affect distance of bullet jump ? I got my COAL to where bullets is .020 of lands full length resized. Since I use a bullet comparator with a modified case thats not fire formed to my chamber to set COAL I was wondering if it would make a difference. The way I see it is....since I didn't bump the shoulders back so therefore the case should be closer to the lands.

 

[fguffey]

head space? The length of the chamber from the shoulder of the chamber to the bolt face. the case does not have head space, the case has a length from the shoulder to the head of the case.

Shoulder/datum.

F. Guffey

 

[fguffey]

COAL or maximum overall length is another length measured from the tip of the bullet to the head of the case. then there is another length, that length is measured from the contact area if the bullet with the lands to the head of the case.

F. Guffey

 

[Countryboy1150]

So basically I can set up COAL just like I full length resized the cases ? I'm not really familiar with headspace that well

 

[witchhunter]

Yes. You can oversize your case in a FL die to create too much headspace in your rifle. Guff is correct the headspace is in your rifle, not your brass. Use the COL you measured before, neck sizing shouldn't affect your length.

 

[Walkalong]

head space? The length of the chamber from the shoulder of the chamber to the bolt face. the case does not have head space, the case has a length from the shoulder to the head of the case.

fguffey is talking about the physical headspace machined into the guns chamber.

A properly sized case will fit the chamber without to much slop front to back between the case head and the breech face with the cartridge fully forward with its shoulder against the "shoulder" of the chamber. Wiggle room front to back. Too much and we have problems. If you neck size brass fired in your chamber, this is a non problem as the brass's shoulder has been moved forward a hair, lessening that slop, or clearance. All you are doing is sizing the neck.

If you were to full length size, you can induce excess slop/clearance, and induce what some of us call artificial head space. While the guns mechanical head space is correct, and has not changed, you have now sized a case undersized (Pushed the shoulder too far back, and induced front to back slop which should not be there.

A drawing is easier than trying to explain it.

http://www.thehighroad.org/showthread.php?t=734058

http://www.thehighroad.org/showthread.php?p=6270171#post6270171

 

[Countryboy1150]

Ok. Thanks alot guys

 

[243winxb]

FL vs Neck Sizing

Sizing methods -

How will that affect the distance of bullet jump ? My bullets are .020" off the lands when full length resized.

Neck sized brass will increase the distance off the lands when using the same COL for both. How much? I would guess any where from .002" to .010" in a bottle neck cartridge. This depends on how much you pushed the shoulder back when FL sizing.

 

[Countryboy1150]

Sizing methods - Neck sized brass will increase the distance off the lands when using the same COL for both. How much? I would guess any where from .002" to .010" in a bottle neck cartridge. This depends on how much you pushed the shoulder back when FL sizing.

Thanks for the info.

 

[Rule3]

243winb, that is a great picture!

Countryboy,

You are talking abound a bolt action rifle yes?

If so you can just neck size, as the case is formed to your chamber, Not full-sizing eliminates the stretching of the brass so the case length is not going to grow very much and no trimming needed.

After a few loads you may have to full size and trim and start over. I keep my 223 and 308 brass separate from all others. Still fits the case gauge and chamber fine.

 

[Rangemaster]

Hey guys I got a issue also, maybe someone can help.

I just formed fired a bunch of 308 down my new ar10. I took a headspace reading of 1.628 to 1.629 avg for the cases.

Now this is where it gets weird, I resized some test brass and the headspace grows not shrinks to 1.632 or more on avg using three different sizing dies. I have lee, Dillon, redding full length dies. Shouldn't the shoulders be bumping back a little bit? I have the die pressing tight on the shell plate also.

 

[Walkalong]

During the sizing process the body is squeezed in before the shoulder is touched, moving the shoulder forward a bit. It only moves rearward when it contacts the "shoulder" in the die. Keep adjusting the sizer down a very small amount at a time until you see it move the shoulder a couple of thousandths.

With the die against the shell plate, it should be moving the shoulder. Something is out of whack. How are you measuring the shoulder position?

 

[Rangemaster]

I am measuring the shoulders with a hornady/Stoney point headspace guages.

I will try and crank down the die a little bit more.

 

[Rangemaster]

I just wrench it down a half a turn on the old rock chucker, man that was tight.
Got it down to 1.625.

 

[Walkalong]

I actually had to take a tiny bit off the bottom of my .223 sizer. If you go this route, be very sure you need to first.

There will be some flex while sizing, so check to see if the die is still against the shell plate while actually sizing a case, not just running the ram up with no case.

 

[Rangemaster]

Walkalong, problem solved.

Switched to my Dillon 1050 which has a little bit thinner shell plate then the rcbs and lee.

Thanks.

 

[Walkalong]

That distance is supposed to be standard (.125), but they were obviously not here.