Resizing new brass?

[Jam50]

Two questions for you experts. These questions are coming from a bolt gun shooter and primarily hunting with the loaded ammo.

Is is required to resize new unshot hornady brass before loading?

What is the minimum pull for .308 and .300 bullets when resizing the brass?

I shot some of my first loads yesterday and at best seen 1" group, I typically see below 1/4" grouping with the factory ammo I shoot.

 

[std7mag]

Brass, (NOT loaded ammo) i full length size regardless of manufacturer.
Check trim length too!

What are you calling "minimum pull"?

 

[JFrank]

Two questions for you experts. These questions are coming from a bolt gun shooter and primarily hunting with the loaded ammo.

Is is required to resize new unshot hornady brass before loading?

What is the minimum pull for .308 and .300 bullets when resizing the brass?

I shot some of my first loads yesterday and at best seen 1" group, I typically see below 1/4" grouping with the factory ammo I shoot.

Where are you getting your load data?

 

[243winxb]

No resizing, if new brass chambers* & holds a bullet. Bullet pull is 35 pounds minimum for a 5.56. My minimum is .002" increase in outside neck diameter after bullet seating.

Larger groups are common, before fire forming for me.
Rem & Win 243 brass. Not an expert.

 

[LHSmith]

No resize. Run it partially in sizing die to eliminate out of round necks.

 

[jepp2]

Is is required to resize new unshot hornady brass before loading?

Depends. I measure the case head to datum on the new brass and compare that with the length that I have bolt contact with on the rifle I intend to shoot it in. 99% of the time, the new brass will be considerably shorter and FL sizing is UN-necessary. However, the case mouths are normally not round and the neck tension may be well beyond what I normally shoot with. So I would run an expander through the case mouth, then break the inside ragged edge of the case mouth with a inside chamfer tool. If you don't do this, it will scratch the bullet jacket when you seat your bullets and this can affect your accuracy.

 

[LHSmith]

I shot some of my first loads yesterday and at best seen 1" group, I typically see below 1/4" grouping with the factory ammo I shoot.

If this is @100 yards(or even @50) buy all of that factory ammo you can. If that is not an option, then measure the base to ogive of that ammo and replicate that dimension in your handloads......you have stumbled upon the sweet spot (BTO) for that gun.

 

[Bill K]

I resize without setting the shoulder back, mainly to make sure neck/mouth is good, then check to see how it slides/closes into a chamber of the rifle I am going to use it in.
If all fits well, even with a slight resistance, I then finish prepping the case and then load it for firing and final forming to the chamber.
I do this with all makes of brass I purchase, I don't care if it is lapua or any of the so called cheaper brass makes.

 

[skeeljc]

I always FL size new brass. It will make sure the neck is aligned with the body. I prefer FL sizing without an expander and expanding the neck in a separate operation with a mandrel. That way I can control the neck tension.

 

[Coyotefurharvester]

I have never encountered new factory brass that would not chamber( I have only purchased one lot during the purge, so quality may have changed) I also have ammo checker for most of my rifles. I just mandrel for neck tension, load and shoot(hunting ammo).

 

[Jam50]

Where are you getting your load data?

Hornady or Hodgdon, one thing I'm finding with my .300 is neither of these sites list the 195 eldm

 

[divingin]

IMO, both Hornady and Hodgdon's (and most others) published load data suffers from Lawyeritis: the max loads are pretty conservative. This is rather subjective, but shows the need to work up a load in your rifle, using the data as a rough guideline or starting point.

If factory ammo will shoot small groups, your handloads should be able to perform as well, or better, assuming you put a little effort into making things as precise as you can (which is a pretty deep hole to fall into, but that's digressing a bit.)

First firing on new brass is with a case that's made to fit pretty much any chamber out there. It may be pretty sloppy in your rifle. It'll take at least one, sometimes as many as 3 or 4 firings to get it to where it's a little better fit for your chamber. One thing you want to do is not oversize it; allow the brass to grow until you actually need to size it to fit the chamber, then address the portion that needs to be addressed (i.e shoulder position or base diameter) rather than blindly squeezing everything back down.

As far as bullet pull, if you're not using a die with a replaceable neck sizing bushing, you're not going to able to adjust it anyway (at least not without sending the die out to be honed), so just run with what you've got. Most factory dies will be in the ballpark. Measure the outside neck diameter after sizing the brass, and again after seating a bullet. Anywhere from .001" to .004" difference should be okay. 2 to 3 is ideal.

Good luck!

 

[Jam50]

IMO, both Hornady and Hodgdon's (and most others) published load data suffers from Lawyeritis: the max loads are pretty conservative. This is rather subjective, but shows the need to work up a load in your rifle, using the data as a rough guideline or starting point.

If factory ammo will shoot small groups, your handloads should be able to perform as well, or better, assuming you put a little effort into making things as precise as you can (which is a pretty deep hole to fall into, but that's digressing a bit.)

First firing on new brass is with a case that's made to fit pretty much any chamber out there. It may be pretty sloppy in your rifle. It'll take at least one, sometimes as many as 3 or 4 firings to get it to where it's a little better fit for your chamber. One thing you want to do is not oversize it; allow the brass to grow until you actually need to size it to fit the chamber, then address the portion that needs to be addressed (i.e shoulder position or base diameter) rather than blindly squeezing everything back down.

As far as bullet pull, if you're not using a die with a replaceable neck sizing bushing, you're not going to able to adjust it anyway (at least not without sending the die out to be honed), so just run with what you've got. Most factory dies will be in the ballpark. Measure the outside neck diameter after sizing the brass, and again after seating a bullet. Anywhere from .001" to .004" difference should be okay. 2 to 3 is ideal.

Good luck!

Thanks!

 

[Ole timer]

I don't recall ever sizing brand new brass. I check to see if it chambers, and it always does. Usually the neck is too tight. I use an expanding mandrel bringing to .001 under, and then use a lee collet neck sizing die if I want it a little tighter. As said above, for a bolt, I shoot them at least twice, and start sizing accordingly.

 

[dgeesaman]

If this is @100 yards(or even @50) buy all of that factory ammo you can. If that is not an option, then measure the base to ogive of that ammo and replicate that dimension in your handloads......you have stumbled upon the sweet spot (BTO) for that gun.

And also the bullet you should be buying.

To the original question, resizing brand new brass should only be necessary if it’s a match chamber.
David

 

[K22]

No expert here - I don't have a strong opinion on either sizing or not sizing new cases but I full size all new cases with an expander ball in place.

Reason: To uniform the cases and aid in aligning neck with case body. The expander ball removes any dents in the case neck and uniforms the necks. If the dent is severe, I first straighten with a mandrel before sizing.

I measure about 3 to 5 cases in the lot with a bump gauge and caliper. I set the sizing die to just touch the shoulder, not push it back or extrude (lengthen) the case. I have several expander ball assemblies of varying diameters. I select one that will give me about .002 to .003 neck tension.

Whether you size or not you should at least chamfer the inside and outside of the necks since sometimes a rough edge exists on new cases. Chamfering will aid is seating bullet and prevent brass particles from breaking off and scaring the neck region of the sizing die.

 

[DocBII]

Jam50,

I just annealed 1.2k 300 WM cases before sizing and prepping. Threw out 21 cases due to defects from as shipped. Resizing was much more consistent, as was the effort to neck turn them.

HTH,
DocBII

 

[17TACnes]

I FL size new brass to remove any distorted case mouth.

 

[Ned Ludd]

I routinely open up the necks on virgin brass using an oversized expander mandrel (.001" under bullet diameter), followed by re-sizing in a die with the appropriate diameter bushing for ~.002" neck tension (interference fit). I have used this brass in local F-Class competitions on many occasions and it shoots very, very well. If your re-sizing die is set up correctly, it will not move the shoulder at all, only squeeze the necks down about .001" from the mandrel step. In my hands, the neck tension for loaded rounds obtained with virgin brass (Lapua) straight out of the box has significant variance. The use of a mandrel that opens all the necks up ever so slightly to a uniform I.D., followed by re-sizing (i.e. sizing back down) with the appropriate bushing generates more uniform neck tension.

 

[Timberyote]

I resize to ensure that the necks are round and uniform.