Neck Sizing and Decreased Accuracy

If a hunting load I'd just stick with the fl die, Only bump the shoulder a few tho.

I have to state the obvious. If FLS brass and that load is sub MOA, don't mess with it.

If collet die neck sizing is causing a significant decline in accuracy, it has to do with the shoulder and playing with seating depth will not change that.

You don't want to be in the field with brass that's been fired a few time and only neck sized. The shoulder needs to be pushed back every few rounds, and you could get to the point where a round may not chamber easy, I like to neck size but if the fl die is used right can be just as accurate.

All my hunting ammo gets fl sized, still 2 moa is plenty good for 270 win range.

Case volume changes between fl sizing & neck sizing. The little 5.56 is 4% difference in volume. The pressure curve changes also.

An increase or decrease in the powder charge may help?

Fl brass will expand on firing, using up some energy.
Neck sized will not expand as much.

Chambers & bolt face may not be inline/square to the bore. Not good if neck sizing.
I have RCBS neck dies that have not be used in many years.

As others have said, just fl size and be done with it.

Well. that difference certainly surprises me. Especially since I have not full length sized any .244 recently and I am running under MOA. Could there be something wrong with your neck sizing die or procedure? I am all for full length sizing hunting ammo. But am from the days when we thought neck sizing was inherently more accurate than full length sizing.

After trying it one time my .308 neck sizing die sits in a drawer, never to be used again. It was clear that neck tension was all over the place and accuracy suffered as a result.

Full length size everything and put those neck sizing dies in the classifieds

Brass, dies, and chambers vary. What works in one gun may not work in an identical one. I have had my best luck setting the FL die so that it just kisses the shoulder. Nature Boy has the right idea about the neck sizing dies.

IME
These are a few things that effect accuracy
Powder charge variances & lot #
Seating depth variations
Primer lot #
Neck tension is a biggie
Bullets lot # are not always the same
qualify each box base to ogive
Notice Concentricity isn’t on the list

as win243xb stated, your neck sized case volume has increased. to get your sub-moa group back, you will have to work up your load again as you have a different case volume.

that said, f/l sizing is better than neck sizing for all the reasons stated above. and i also recommend sticking with the f/l resizing die and relegating the neck size die to the back of the shelf.

luck,

murf

I loaded a sub-MOA..using Lee FL sizing dies...seated just off the lands.

Neck sizing with the Lee Collet Die using the same seating depth and powder charge opened up the group to 1.5-2 MOA.

I was wondering if I should keep the same powder charge and play with the seating depth.

Click to expand...

You could but you already know that you can get better accuracy with a different die at that depth with that charge.

If I wanted to learn something I didn’t know, I’d put the collet die back in the plastic box and back the FL size die out a bit, so it’s only sizing the neck of the case, and see what that does.

Personally, I would interpret these results thusly:

A load which falls apart simply due to neck sizing rather than full length sizing, or vice versa, is not a load I would entertain, or even NEAR a load I would entertain. The “secret” to loading, in my opinion, is to focus upon finding windows where loads are forgiving - meaning slight variations in loading practice or process will not yield large deviations on target.

Whether the driving variance in your case is the neck tension difference between the two dies, or the slight difference in case capacity, either can’t be so significantly varying, and can’t be so significantly influential such they should yield such dramatic deviations in group size. Something is wrong with the load if it is that sensitive - it’s balancing on a razor edge - so it really wouldn’t be a load I would pursue.

Personally, I’d look at that load like a redhead sitting at the corner of the bar, alone, at 1:50am, smoking a cigarette over a glass of dark liquor on the rocks... no matter how good it might look, just keep on walking...

I had a thing for Redheads when I was a younger man.
Now my heart won’t take it

Nature Boy said:

After trying it one time my .308 neck sizing die sits in a drawer, never to be used again. It was clear that neck tension was all over the place and accuracy suffered as a result.

Full length size everything and put those neck sizing dies in the classifieds

Click to expand...

Same experience for me with my 6.5

There are other factors that can cause different group size as well like temperature, humidity, and elevation. We're all the groups shot at the same place with the same weather conditions?

How many times have the cases been fired? Have they been annealed to soften the brass back up?

Just curious.

Improper annealing can ruin brass quickly, ask me how I know that

When neck sizing with a Lee or similar die, the amount of weight on the press handle is important . The Lee needs at least 25lbs you can hang a weight of the handle for more consistent sizing.

First questions first: (1) How many shots in each group? (2) How many groups fired with with each load?

dak0ta said:

Hi,

I loaded a sub-MOA load at 100m with my .270 Winchester using Lee FL sizing dies and Nosler 150 gr Ballistic Tips. I am using IMR4831 53.5gr. The bullet is seated just off the lands.

Neck sizing with the Lee Collet Die using the same seating depth and powder charge opened up the group to 1.5-2 MOA.

I was wondering if I should keep the same powder charge and play with the seating depth. I know FL sizing may be more accurate as it allows the bullet and case to centre itself into the bore (cone within a cone). Perhaps neck sizing negates the cone within a cone advantage and seating the bullet at the same depth makes it enter the rifling off-axis? Would prepping some reloads with progressively deeper seating depths yield improvement? The 53.5gr powder charge was the most accurate out of my FL sized samples.

Click to expand...

BTW; were you using wind flags when testing?
Are these loads tested on different days ?

Here’s the same load on the same day under two different wind conditions.
If I didn’t know better I’d swear the load was goofy