Head Spacing before Sizing

[WyldeShot]

I bought a new CTS trimmer. I was receiving inconsistent trim lengths. I spoke to Jim at CTS and he was asking me about head spacing and if I used the head space gauge that came with the trimmer.
I had not used the head space gauge that came with the trimmer.

Jim gave me some instructions that included shooting a 5.56 and insert the case into his head space gauge to get the value for my rifle so I know what I should size the case to. According to him, the post sized case should be .006-.008 less than the size of the fired case. I discovered that my post sized cases were the same length as the case that I had fired.

This tells me that I was not properly sizing my cases right? This is probably why I had an issue extracting a couple of rounds from my AR.

Who all checks their head space so they know what the resizing die needs to be set to or do you just give your resizing die another 1/2 turn after meeting the shell plate?

I have not trimmed any of my newly sized brass to see if trimming is more consistent yet. I hope to do some trimming this week.

 

[red_zr24x4]

I trim to what the book says the length is.
After sizing a case I make sure it chambers easily. Never had an issue.

 

[Kart29]

I check headspace with a simple homemade ring gage and set of calipers. Not the best measurement but gets me close enough to know the headspace of my chamber and how much my sizing die is moving the shoulder back.

I'm not sure how trim length fits into this. Is this a pistol caliber that headspaces on the mouth of the cartridge? Trim length shouldn't effect headspace on a 5.56 NATO round at all, I wouldn't think.

 

[WyldeShot]

I check headspace with a simple homemade ring gage and set of calipers. Not the best measurement but gets me close enough to know the headspace of my chamber and how much my sizing die is moving the shoulder back.

I'm not sure how trim length fits into this. Is this a pistol caliber that headspaces on the mouth of the cartridge? Trim length shouldn't effect headspace on a 5.56 NATO round at all, I wouldn't think.

This is no .223/5.56. The idea is that the trimmer trims off of the shoulder. If the shoulder is not consistent then the trimming will be inconsistent. This is my thoughts anyways.

 

[Yeah]

Who all checks their head space so they know what the resizing die needs to be set to or do you just give your resizing die another 1/2 turn after meeting the shell plate?

I only ever size rifle brass to the chamber I intend to use for firing it, because finite headspace control is among the leading benefits of reloading where accuracy and precision are concerned.

Almost no one sets up sizing dies correctly and screwing it further into the shell holder after it has made contact it a step in the wrong direction.

 

[WyldeShot]

I only ever size rifle brass to the chamber I intend to use for firing it, because finite headspace control is among the leading benefits of reloading where accuracy and precision are concerned.

Almost no one sets up sizing dies correctly and screwing it further into the shell holder after it has made contact it a step in the wrong direction.

Care to share how you set your resizing die up? I was thinking about getting a set of Redding Comp shell holders.

 

[Fullmag]

I check headspace with a simple homemade ring gage and set of calipers. Not the best measurement but gets me close enough to know the headspace of my chamber and how much my sizing die is moving the shoulder back.

I'm not sure how trim length fits into this. Is this a pistol caliber that headspaces on the mouth of the cartridge? Trim length shouldn't effect headspace on a 5.56 NATO round at all, I wouldn't think.

The trim length is the overall length of the case from the base to the end of the case at the neck. Every time a case is fired then resized the neck gets longer. It does become dangerous when the case gets longer than the chamber it was made for.

 

[NKBJ]

If you are loading for one rifle only, size to that rifle.
And, if you do a pound cast and take accurate measurements of the shoulder to case neck end in the chamber, trim for that chamber.

About trimming, something that happens sometimes with trimmers is that the consistency of the case rim diameter can slightly alter how the case is held.
In a small case like a .223 that effect can be more significant.

In a bangety-bang-bang AR just size and trim to standard specs that are intended to prevent problems.
Then if you get a problem you know if twern't you.

 

[Yeah]

Care to share how you set your resizing die up? I was thinking about getting a set of Redding Comp shell holders.

On a new-to-me sizer I flush the thing thoroughly with a solvent. Paint thinner or MEK are usually handy. I then work its interior over with 0000 steel wool, feeling for any burrs or machine marks to be dealt with. Once it is verified slick I degrease again and blow it dry with compressed air.

Insert a shellholder and bring the ram to the top. Run the die's lock ring up and thread the die into the press until it contacts the shellholder. I eyeball the interface to make sure the contact is reasonably even all the way around. Shellholder's can take a beating and you want them to nestle the die nice and square or there will be problems right out of the gate. I keep several spares of all sizes on hand in the event alignment is not happy.

Interface verified, I back the die out of the press 3/4 or so revolution and snug down the lock ring. Remove decapping rod and expander.

Locate a case-to-be-sized that has been sprayed from all directions with OneShot, and a black sharpie. I use the sharpie to paint the case from below its shoulder to the top of its neck, all the way around. The marker needs to dry thoroughly.

I snick the case into the shellholder and cycle the press. The impression the die leaves on the case will indicate exactly what is being touched, and I'm adjusting the die further into the press with each cycle. Once I'm pleased with the progress on the neck, and the marks indicate the shoulder has been bumped, I'll test the empty brass' fit into the chamber of the rifle(s) that it is destined to be fired from. Here I want to have moved enough brass that the bolt will need slight pressure to get it into battery. I don't want to have to slap it home but I don't want it falling into place as if the chamber were empty.

Moving as little brass as possible lets it live as long as possible, with the side benefit of doing wonders to accuracy and precision.

It is worthwhile, once nirvana is reached and before tightening the lock ring's set screw, to chamber four or five pieces of brass so sized. This hedges against any concentricity issues in the chamber or dies and provides a sample size adequate to base sizing another 500 pieces of brass with the setup.

With the die locked in place, run the decapping rod down until it peeks out of a flash hole, and go to resizing the lot.



This obviously works best on a bolt rifle where one can feel resistance upon chambering. The method can be adapted for semi autos by feeding test sized cases from a mag and visually verifying the bolt reached battery. I tend to run the die a bit further into the press once I'm comfortable battery is being consistently reached, thus bump the brass a bit more. This aids feed and function, which I'll happily trade for the slight accuracy and brass life impact.

 

[Broom_jm]

Very good explanation, Yeah. I'll only add that I start with the mouth of the resizing die about the thickness of a nickel away from the shellholder, with the ram all the way up. More often than not, brass is sized sufficiently with the mouth of the die about the thickness of a dime away from the shellholder. Again, this is for bolt action rifles.

For semi-auto and lever-action rifles, which lack the strength of a bolt action, I usually wind up with the die touching the shellholder, to ensure cases feed/extract well.

 

[WyldeShot]

On a new-to-me sizer I flush the thing thoroughly with a solvent. Paint thinner or MEK are usually handy. I then work its interior over with 0000 steel wool, feeling for any burrs or machine marks to be dealt with. Once it is verified slick I degrease again and blow it dry with compressed air.

Insert a shellholder and bring the ram to the top. Run the die's lock ring up and thread the die into the press until it contacts the shellholder. I eyeball the interface to make sure the contact is reasonably even all the way around. Shellholder's can take a beating and you want them to nestle the die nice and square or there will be problems right out of the gate. I keep several spares of all sizes on hand in the event alignment is not happy.

Interface verified, I back the die out of the press 3/4 or so revolution and snug down the lock ring. Remove decapping rod and expander.

Locate a case-to-be-sized that has been sprayed from all directions with OneShot, and a black sharpie. I use the sharpie to paint the case from below its shoulder to the top of its neck, all the way around. The marker needs to dry thoroughly.

I snick the case into the shellholder and cycle the press. The impression the die leaves on the case will indicate exactly what is being touched, and I'm adjusting the die further into the press with each cycle. Once I'm pleased with the progress on the neck, and the marks indicate the shoulder has been bumped, I'll test the empty brass' fit into the chamber of the rifle(s) that it is destined to be fired from. Here I want to have moved enough brass that the bolt will need slight pressure to get it into battery. I don't want to have to slap it home but I don't want it falling into place as if the chamber were empty.

Moving as little brass as possible lets it live as long as possible, with the side benefit of doing wonders to accuracy and precision.

It is worthwhile, once nirvana is reached and before tightening the lock ring's set screw, to chamber four or five pieces of brass so sized. This hedges against any concentricity issues in the chamber or dies and provides a sample size adequate to base sizing another 500 pieces of brass with the setup.

With the die locked in place, run the decapping rod down until it peeks out of a flash hole, and go to resizing the lot.



This obviously works best on a bolt rifle where one can feel resistance upon chambering. The method can be adapted for semi autos by feeding test sized cases from a mag and visually verifying the bolt reached battery. I tend to run the die a bit further into the press once I'm comfortable battery is being consistently reached, thus bump the brass a bit more. This aids feed and function, which I'll happily trade for the slight accuracy and brass life impact.

Awesome! Thanks for taking the time to explain. I have not been reloading for a long time and I think there are a couple of things I've been doing incorrectly. I want to fix those mistakes.