Expander mandrel
- Thread starter ffgats
- Start date
The whole idea of it is to get consistent neck tension. How would you get that tension consistent with only a partial neck expansion.
I also anneal on every case after firing. Size without the expander ball, then run my mandrel. Again its about consistency.
I also anneal on every case after firing. Size without the expander ball, then run my mandrel. Again its about consistency.
It's quite possible to get consistent neck tension with only partial resizing of the neck.
I have a couple of rifles that I partially resize the necks on the handloads made up for it.
The chamber is cut on the large side of median spec, so the case needs very little resizing at any point, other than where the neck holds the bullet.
The purpose of the neck isn't just for tension but to hold the bullet concentric to the axis of the bore as close as possible.
In the old days it was common for cartridges to have long necks to hold long, heavy bullets as straight as possible as they entered the leade. With modern cartridges and tighter tolerances, this isn't as important.
By only partially resizing the neck, especially on rifles with close to max spec chambers, keeping a bit of the neck portion to the same diameter as the chamber can help with accuracy.
I have a couple of rifles that I partially resize the necks on the handloads made up for it.
The chamber is cut on the large side of median spec, so the case needs very little resizing at any point, other than where the neck holds the bullet.
The purpose of the neck isn't just for tension but to hold the bullet concentric to the axis of the bore as close as possible.
In the old days it was common for cartridges to have long necks to hold long, heavy bullets as straight as possible as they entered the leade. With modern cartridges and tighter tolerances, this isn't as important.
By only partially resizing the neck, especially on rifles with close to max spec chambers, keeping a bit of the neck portion to the same diameter as the chamber can help with accuracy.
I size the full neck for some rifles, and only slightly more than the seating depth for others. My 222, for instance prefers me staying away from the shoulder, so I set the dies up to only size about .225 or so down. I know this isn't what you asked, but the priciple is the same. Every once in a while I need to ream out the donut on these rounds though. Since I'm only seating the bullet .224, tere's no need to size the neck any further down than that.
As for neck tension - there are other ways to control that, but the mandrel is definitely the easiest and most common. I know guys that don't use an expander at all. They control neck tension with bushings and neck turning only.
ffgats, try it both ways and see what works better for you - as bearhunter said, some rifles like the shoulder/neck transition area closer to chamber dimensions for accuracy, and in other rifles it won't make any difference at all. Depends on so many things you may not have even thought about, like whether the action/bolt is trued, how precisely and tight the chamber was cut, some guys think that even the type of ejector you have can make a difference when it comes to bore alignment (eg. Tikka and Remington).
As for neck tension - there are other ways to control that, but the mandrel is definitely the easiest and most common. I know guys that don't use an expander at all. They control neck tension with bushings and neck turning only.
ffgats, try it both ways and see what works better for you - as bearhunter said, some rifles like the shoulder/neck transition area closer to chamber dimensions for accuracy, and in other rifles it won't make any difference at all. Depends on so many things you may not have even thought about, like whether the action/bolt is trued, how precisely and tight the chamber was cut, some guys think that even the type of ejector you have can make a difference when it comes to bore alignment (eg. Tikka and Remington).
Last edited:
Where did you find new Lapua 6BR brass? It's impossible to find this year.
When I received my new 6BR brass (3 years ago), I ran it over a mandrel to take the dents out of the necks. Then loaded with primer, powder, bullet, and fired it.
Since then, it gets this process:
-clean in ultrasonic
-anneal
-lube with the tin of die wax by latex gloved hand
-run through Dillon 650: full length bushing Whidden die with decapper; primed; mandrel
-wipe the lube off outside by brake clean and paper towel and hand
-charge and seat bullet on a single stage RCBS rockchucker
About every third firing I trim/chamfer/debur.
Once so far in 7 firings I have done a light pass with a old school neck turner.
When I received my new 6BR brass (3 years ago), I ran it over a mandrel to take the dents out of the necks. Then loaded with primer, powder, bullet, and fired it.
Since then, it gets this process:
-clean in ultrasonic
-anneal
-lube with the tin of die wax by latex gloved hand
-run through Dillon 650: full length bushing Whidden die with decapper; primed; mandrel
-wipe the lube off outside by brake clean and paper towel and hand
-charge and seat bullet on a single stage RCBS rockchucker
About every third firing I trim/chamfer/debur.
Once so far in 7 firings I have done a light pass with a old school neck turner.
I think you are asking if I run the neck bushing down the whole neck. I think I do. The instructions for this die say to insert the bushing, and then tighten the upper cap that holds it in until the bushing can just barely click up and down when I shake the die. So that is how I run it. From looking at the neck, it looks like the whole neck is sized to the same diameter - I can't see where the bushing stops working.
i have only ever expanded full length as I want a consistent uniform tension using only a "pushed" mandrel and not dragged. The expander mandrel gives a lot more uniform tension doing full length from my experience without giving it an excesive squeeze on the projectile.
I could only ever see doing partially expanded neck useful if you wanted a lot of tension on a flat based projectile but I would still be inclinded to do a Lee Factory crimp following to uniform out inconsistencies which imo kind of makes the partial neck expansion irrelevant in the first place if using FCD.
I could only ever see doing partially expanded neck useful if you wanted a lot of tension on a flat based projectile but I would still be inclinded to do a Lee Factory crimp following to uniform out inconsistencies which imo kind of makes the partial neck expansion irrelevant in the first place if using FCD.
Terry Perkins
CGN frequent flyer
- Location
- Bruce County
I have found new Lapua brass to be quite tight. You should test first with the mandrel.
^^^ Yes.
My experience with new Lapua 30-06, .260, and 6.5 x 47, necks are very tight. I expand the entire neck first with my Sinclair or 21st Century expander die and appropriate mandrel per caliber. And you will need lube inside the necks, or else brass will begin to plate onto the mandrel. (Don't ask me how I know this!)
Also I find the new Lapua brass neck edge is very square and sharp enough to shave bullet jacket. It needs chamfering and deburring.
Once that is done, its ready for its first firing.
After firing, for each resizing cycle, after resizing I run my Sinclair or 21st Century expander mandrels full neck. The partial neck sizing (if desired) is controlled by the bushing dies and depth of the bushing. Carbon on fired brass inside of the neck is often enough to not need lube for final expander mandrel operation. If lube is needed, I use the Redding dry graphite lube. I have also used Lee lube inside tight necks for expanding, because its water-based and (when dry) will not contaminate the powder and powder granules won't stick to it when charging cases.
Last edited:
On fired brass I set up the die to touch ~90% of the neck with the expander ball removed. I then run an expander through the neck.
I don't know how you could get good results by only running the expander part way in. What you would end up doing is expanding the remainder of the neck with the bullet when you seat it.
Running the expander only part way in?????
The expander will only work on the section of the neck that's been swaged down by the sizing die, so it isn't going to make any difference if the system is being used properly.
I like to leave the bottom 15%, appx, of the neck as is, after firing then resizing. There are a couple of reasons for this, mostly the extra diameter at the base of the neck helps to center the bullet to the axis of the bore and as such it should feed concentrically into the leade, without even the tiniest bit of cant.
It's an old, tried and true way to keep 303 Brit and other cartridges with sharp tapers concentric to the axis of the bores of the rifles they're being handloaded for. Works very well.
This can be a real issue for older rifles, especially milsurps, which almost always have excessive freebore as well as generous dimensions, which all lead to bullet canting before they enter the leade and having a negative influence on accuracy.
One thing many younger folks don't understand or know about case neck length is why the makers adopted those lengths.
Back before my time shooting, it was quite common for cartridges to have very long necks.
Today, some look at those designs and shake their heads, but there was a very good reason for what appears to be extra lengths.
The first reason was the powders available at the time were terribly inconsistent and temperature-sensitive, even the black powder.
With the heavy and long for caliber bullets being the norm, the bullets were seated deeper into the cases and the longer necks provided more tension, that was more consistent.
There wasn't any reason to make the powder section of the case larger or even smaller, because most of the powders back then were designed to give specified results for the parameters they were to function in.
The other reason for longer necks was to "hold" the bullet, under tension as long as possible before entering the leade and eliminating as much bullet cant as possible before entering. Considering the accuracy requirements of the day for cartridge-loaded rifles, those long necks did a pretty good job, as long as the freebore was kept to reasonable depths. The less distance the bullet has to jump from the case mouth to the leade, the more consistently accurate the load will be.
Under new manufacturing standards, freebore has been almost eliminated or its negative effects countered by keeping the throat dimensions very tight to the dimensions of the bullet, thereby eliminating the need for long necks.
The 300Savage is a good example of this. The firearms first made for this cartridge had short for the day throats, as did those for the 257 Roberts and a few others.
I can remember reading articles in the old magazines and papers on this, where the talking heads and purists decried this "new" tech and predicted it to fail miserably.
Today, it's pretty much the norm and its only drawback is the varying chamber dimensions encountered when purchasing off-the-shelf rifles and pairing them with off-the-shelf factory ammo.
The Model 94 Winchesters are notorious for being ammo fussy. This comes from a blend of "old tech" with new tech. Most of the Model 94 Winchester rifles I've seen have chambers that are cut on or close to max specs and that includes headspace.
This is easily overcome by hand loaders who only partially resize the cases and set headspace off the shoulder, rather than rely on rim thickness.
When Model 94 rifles are fed in such a manner, they usually shoot very well.
The 30-30Win is another taper case cartridge with a long neck.
