Thin turned necks & Tension
- Thread starter shinny
- Start date
Boyd Allen
Active member
Your loaded round neck diameter, over the bullets pressure ring will be what ever two times the neck thickness plus the diameter of the pressure ring adds up to. Your bushing size should be .002 to .003 smaller than that. Why not just seat a bullet, and measure? Before I had a neck thickness mic., I checked my neck thickness this way. Everyone should have a 1" micrometer that measures to .0001.
pbike
New member
I believe that the old conventional thought is that if you are shooting a .262 neck, you should have .0086 neck walls, and use a .258 buttons. The newer aproach which is to shoot with thinner necks and stay at .262, but have necks that are only .0082. The result is less O.D. for a loaded round, more slop in the chamber, and that .258 button will now not give you enough neck tension. So guys have been going to .257 and .256 buttons. I am trying the same thin neck approach this year with my.330 neck .30 BR, we shall see.
J
j mckinnie
Guest
Paul
the unsized portion of the neck dowm near the shoulder stops the wobble/slack your refering to.If I'm on the same page?
jim
the unsized portion of the neck dowm near the shoulder stops the wobble/slack your refering to.If I'm on the same page?
jim
What Boyd said.
Except:
1. Are you using N-133? Some powders seem to shoot best with very little neck tension. Back in the 322 and even 2015 days, a lot of people didn't bother with arbor press. Just use your thumb on the seating stem. Dunno about you, but I can't do that if the neck is .002-.003 under final size.
2. Are you going to anneal your brass, or throw it out after one 4-gun match? If not, you'll need another bushing.
Except:
1. Are you using N-133? Some powders seem to shoot best with very little neck tension. Back in the 322 and even 2015 days, a lot of people didn't bother with arbor press. Just use your thumb on the seating stem. Dunno about you, but I can't do that if the neck is .002-.003 under final size.
2. Are you going to anneal your brass, or throw it out after one 4-gun match? If not, you'll need another bushing.
pbike
New member
Jim,
Are you sizing with a full length bushing die like the "S" die or are you using a wilson bushing sizing die? On our bushing dies, (carstensen/hornady and carstensen/redding) the bushing goes right down to the shoulder. Either way, the body portion of the die sizes the body, we adjust to get the shoulder bumped just enought so the brass is just barely snug in the chamber, and when I say Loose I mean the area around the neck while it's in the chamber. The case isn't loose, the body and the shoulder are holding it in possition. I believe the idea behind a thinner neck is that the neck will loosly hold the bullet in alignment and allow the bullet to enter the bore as it aligns itself. This way if you have a gnats hair of concentricity issues, the looseness allows the bullet to align in the freebore as you close the bolt. I hope I explained that the way I understand it.
Paul
pbike
New member
I have a pic of that die in the Hood press. You can see the different stem assembly then the one used on standard redding dies. It's actually a .30 BR die, but in the pic, I just grabbed a 6 BR brass and placed it in the shell holder.
Here is a pic of a standard redding full length s type die
Here is a pic of a standard redding full length s type die
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Shinny,
I just tested the 262 neck, Lapua brass to .0082" and the 2570, 2575, 2580 and 2585 bushings. The 2570 was demonstrably better for me. This with a "healthy" (read large) dose of N133 - the order of 30-30.2gn with Barts 65gn BT 0.0020" back from jam length. Be warned this is particularly warm.
Peter
I just tested the 262 neck, Lapua brass to .0082" and the 2570, 2575, 2580 and 2585 bushings. The 2570 was demonstrably better for me. This with a "healthy" (read large) dose of N133 - the order of 30-30.2gn with Barts 65gn BT 0.0020" back from jam length. Be warned this is particularly warm.
Peter
I usually just sit back and take it all in,but, this subject intrigues (sp?)me to no end(yes, sometimes I lay awake at nights thinking about this very subject---thin necks) I have been only shooting BR for alittle over 2 yrs., but the man who got me started has been shooting for a loooooooong time and is a BR gunsmith too boot. My Harrell's 6ppc die sizes the neck approx 90%.
I am of the understanding that the reason----shoot thin to win---is so that when fired, the neck releases the bullt with more clearance,thus eliminating the chance of some bullet drag on the inside of the neck during its journey to the target. I hope I am making sense. Keith
I am of the understanding that the reason----shoot thin to win---is so that when fired, the neck releases the bullt with more clearance,thus eliminating the chance of some bullet drag on the inside of the neck during its journey to the target. I hope I am making sense. Keith