How far to size down the neck?

J

JRB

Guest
Just wondering if there is a rule of thumb, for how far to size down the case neck?
Just a note, i do not have a custom FLS die, and i ask this question relating to BR caliber's other than, and including the PPC.

Is there a relationship between the end of the bullet and the sized length?
I have been sizing about 2/3 to 3/4 down, to ensure it is .060-.080" past the end of the bullet, but still leave a little neck, to keep the case 'concentric', just in case there is any gain in that?
Is there any difference between flat base and boat tail bullet designs
Keen to hear your thoughts?
Jim
 
JRB said:
Just wondering if there is a rule of thumb, for how far to size down the case neck?

all the way to the shoulder

Just a note, i do not have a custom FLS die, and i ask this question relating to BR caliber's other than, and including the PPC.

if you're attempting to neck size using a typical off the shelf FL sizer you'll have trouble as the shoulder will start squinching andf shoving forward as you come down the neck

Is there a relationship between the end of the bullet and the sized length?

I have no idea what you're asking here but will have to say "yes"


I have been sizing about 2/3 to 3/4 down, to ensure it is .060-.080" past the end of the bullet, but still leave a little neck, to keep the case 'concentric', just in case there is any gain in that?

no gain IMO

Is there any difference between flat base and boat tail bullet designs

yeahh


Keen to hear your thoughts?

can you be more specific with your questions?


Jim
Click to expand...



answers in bold
 
I think that we all need to take note of that particular piece of information. Not to many of us have the equipment to measure what he reported, and no one else that I know of has his level of experience with it.
 
13 years ago,when I was new to the sport of BR. I used a wilson(Bushing) neck sizer. Many of us used Wilson neck sizers during that time. As I recall,The full length neck sizer was just beginning to gain popularity.

The Wilson neck sizer,with bushing,left a noticeable portion of the case neck unsized. I was always of the opinion that the Wilson Dies were intentionally designed to enhance accuracy,by leaving an unsized portion of the neck. Some of us were not happy with the way the Wilson factory dies sized case necks. Some bullets would seat past the pressure ring causing inconsistent seating depth when the bolt was closed.(?) The solution was to shorten the Wilson die which caused the bushing to size further down the neck. I had one of my Wilson Dies modified to size further down the case neck. The fix worked great with some new bullets I was trying to get to work in my rifle.

Mr Murdica's Explanation is consistent with what I've been told about neck sizing.
 
There is no need to size any of the neck below the part that holds the bullet. The unsized portion of the neck improves alignment of the bullet in the chamber. For that matter, you don't have to size down to the bottom of the bullet, only enough to hold it securely enough so that handling the round and dropping it into the chamber don't misalign it. Lou gives good advice to size at least down to the pressure ring to keep the pressure spike consistent. Previously, I have sized down to the lowest extent of the full diameter part of the bullet (the base on a flat base bullet, above the base on a boattail bullet). That ends up being about 1/4 to 1/3 of the neck on my BR cartridges. Looks like I could try sizing even less. Thanks, Lou.

Cheers,
Keith
 
In my .30's I've found no accuracy difference between sizing the entire length of the neck or leaving a small portion unsized when using a significant amt. of 'jam'.The one barrel I have that doesn't like much 'jam' works better leaving a small portion at the base of the neck unsized. My 6PPC with .025-.030 'jump' absolutely worked better with a bit of unsized neck. As Lou mentioned, leaving a bit of unsized neck at the bottom helps with the seal.

Like a lot of things, there's a lot of "...it depends" involved. -Al
 
Gentlemen,
Thank you for your in depth reply's
I have never really done any testing on different neck sizing lengths, and have been using Wilson neck dies for years, so may have become accustomed to the appearance also.
I was keen to see if there was any definitive thoughts on this, and learn more, i appreciate your comments.
Good Shooting!
Jim
 
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