Splain me neck sizing

[Tree Rat]

What is the difference between neck sizing using a bushing type die as oppossed to neck sizing using a standard sizing die with a sizing button on the de-priming stem?

Can you use both in the same operation?

What exactly is one doing doing to the profile of the shoulder when bumping it to any degree?


TR

[AdamN]

A bushing type die gives you control over that ammount of sizing you need. With a bushing die there is no expander that is drawn back thru the brass.

With a regular die the neck is sized down past where necessary and the expander is drawn back thru. Some feel it works the brass more than necessary but for regular commercial brass being slightly out of round and other variables its the best solution.

When you bump the shoulder youre not changing the profile at all. In benchrest where a lot of this originated; neck sizing was the thing but as a piece of brass was fired several times with just neck sizing people were finding that the loaded rounds were getting more difficult to chamber.

The original solution was to full length size and re-fireform the brass. Then continue with the whole neck sizing only thing.

Guys were discovering that there groups when fireforming were just as good and sometimes better that the neck sized brass.

Then the thing to do was get the bushing style die, the bushing sized to reduce the neck for the correct ammount of bullet tension, size the base of the brass and bump the shoulder a thousandth or so.

The brass chambers easily which makes for fast reloads and doesent upset the gun in the bags. That makes for shooting better groups in the heat of a match.

[918v]

Actually, with the present crop of body dies (shoulder bump dies) do in fact change the dimension of the shoulder. Redding, for example, reduces the diameter of the shoulder to the same degree as their regular FL die, which sizes the shoulder down by .003"

Sizing with a neck die does not touch the shoulder. Using bushings eliminates the need for an expander plug if all your case necks are even. If they are not, then you should use one to make sure the tension is even.

[Tree Rat]

Very good.

So bushing size the neck unless they are out of round in which case you button size the ID?

I like the Redding S-type or Competition bushing die concept but was wondering why they would offer a button sizer as an option if the bushing feature was the way to go.

Do their body dies just resize the shoulder and not do full length?


TR

[ISUSteve]

Small but important points:

It only does any good if fired in the same gun

Bolt guns and single shots only, no semis or levers

[918v]

Very good.

So bushing size the neck unless they are out of round in which case you button size the ID?

I like the Redding S-type or Competition bushing die concept but was wondering why they would offer a button sizer as an option if the bushing feature was the way to go.

Do their body dies just resize the shoulder and not do full length?


TR

Their body dies are FL dies sans the neck sizing part.

They offer the button sizer as an option because most necks are not identical in thickness. Some are as much as .002" thicker than others. Therefore, when you size all the necks in the same bushing, some will size down more than others. The inner diameters will vary by .002" and so will the neck tension. The button sizer will open-up the necks to a similar inner diameter and neck tension will remain consistent for the most part. Of course, the best way to avoid this is to turn all the necks to the same thickness.

Why bother with those bushing dies?

Because they size the necks less than standard FL dies and brass lasts longer.

I prefer custom FL dies, though. Less runout post sizing.