Setting neck tension with expander mandrel and bushing die questions

[antelopedundee]

I see, the difference in the mandrel vs button expander, mandrel expands the neck while being inserted into the case while the button expands while being withdrawn from the case-if it is used as part of the initial sizing process. Another added step to the reloading process...

Both types must be inserted and removed. There are 3 types of expander buttons. The normal one with a rim, a tapered type and a football shaped one. The advantage of the Sinclair mandrel is that it provides 100% contact of neck and mandrel whereas the other 3 aren't even close to that. The extra step if needed is probably well worth it.

Here are a few different expanders I found when looking through my die sets which are mostly Redding and a couple RCBS.

From Left to right. Typical ball style expander. Football or egg shaped expander which is free to float and hopefully stay centered as needed. 3rd is ball type with a long contact surface and last a tapered type. Also pictured is a Sinclair mandrel. The advantage of the Sinclair is that it is always in contact with the neck whereas the other 4 are pushed completely through the case neck and then pulled up back through it

 

[Philward]

This discussion of expander buttons and mandrels had me looking over mine and polishing as needed. When I pulled the Lee 270 win die apart I was surprised to see this. Much larger than the rcbs button. Explains why it's smoother to extract cases with the Lee.

 

[cdherman]

Notice that the sinclair mandrel has an ogive to it. It goes in smoothly. None of the jerk and pull that can happen with an expander ball, especially if the neck is not perfectly lubed.

The Sinclair mandrel, coupled with careful attention to not over size (by using bushings), sides in with just a little graphite. That means I can load that case right away. If I had used wax or greasy lube, I'd need to clean the case first.

And for the crowd that says you can get more perfection by turning necks, my reply is that stuff is for benchrest shooters and perhaps a people that make a living this way. But me, I like to shoot some too, and turning necks is a pain..... But I agree that fundamentally, a perfectly turned neck, custom tight chamber and bushing dies to achieve exact identical tension on the bullet is probably better by some fractional small percentage. Just maybe not enough to matter.

 

[Mikecr]

Neck turning serves to reduce runout and reduce neck tension. This, lowering variance of neck tension.
But it doesn't change the root benefit of pre-seating expansion, which is to bias neck energy (springback) inward rather than outward

While necks are trying to spring back inward, but cannot because of a seated bullet, the bullet gripping force holds as constant. Basically, at max available from the brass.
While necks are trying to spring back outward, which they are free to do, the gripping force reduces over time.
Here, spring back variances are normalized to cause higher tension variance.

There is no scenario where proper neck downsizing followed by proper neck expansion is detrimental.
As with many other areas, the proper part of this is allusive to most..
They migrated from basics to what they think is more advanced without ever actually learning the basics.

 

[marchboom]

With regards to neck turning, after using a bushing alone handloaders see a reduced runout on the neck and sometimes assume that the bullet should now be concentric with the bore. But what about the concentricity of the inside of the neck? Isn't this the most important area that should be concentric? This is the part that "should" hold the bullet concentric to the bore.

Although I'm always learning and will NEVER assume that I know it all, my current method is to use a mandrel to do the neck sizing. I really don't care what the relationship is between the outside of the neck and the chamber. Bullet-to-neck concentricity and tension is what I think is the most important.

But, like I said, I'm always willing to listen to other handloader's thoughts and make changes accordingly.

 

[Blackhawk]

So this is my first time using the expander mandrel. I just got in the mail a whidden gunworks click adjustable full length bushing die for my 300 prc. I ordered the Sinclair expander die and the 30 cal carbide mandrel before the sizing die. To my understanding, people are just taking the expander ball out of their Redding or similar bushing dies, sizing the case and neck with the bushing, and then running the brass through the expander die to expand it. My first question is, do the whidden dies have an expander mandrel or do they come with the ball, to me it looks like a mandrel and I can post a picture of what I got if you guys want. My second question is, can you guys explain your process when setting neck tension with a bushing die and expander mandrel? Without turning necks. From my understanding a guy would select the correct bushing after measuring the neck of a case with a bullet seated in it, size the case with said bushing, and then run it through the expander die with the mandrel. Am I missing something or just overthinking it?

" Points To Ponder"
At least when you use the Sinclair Expander Die Body you can elect to expand your case neck's I.D. by + .001" by using the correct Expander Mandel.
The over size +.001" will allow you to easily have your cases mouth slide over your neck turning tool in order to neck turn and thus remove any TIR Concentricity issiues.
The undersize mandrel will lets say expand your already FL resized brass that has been sized with a bushing die back to a diameter that will allow your bullet to easily start into your case mouth. This step can be done for jacketed bullets, however it is usually performed prior to the seating of lead bullets.
With the above statement I feel that I must qualify.
When you use a bushing FL resizer normally your bushing would be -.002 = -.003" under your case neck diameter with a bullet that has been seated. That is in theory ,however I have found that in order to achieve a uniformly even neck tension you may wind up on the plus or minus side of your initial measurement. This may result in your having to purchase additional sizing bushings say + or - .001" from your reference dimension. This will become more inherent if you order your FL bushing before you have reduced your case necks dimensions by as little as -.0002 -.0005" by the neck turning as noted above . You may find your neck tension has also gotten looser hence your need for a smaller bushing.
On the other hand if your brass case necks ID is too small you can re establish the correct size ( -.001") to allow for your bullet to be correctly start into your case mouth while still retaining correct bullet tension by simple insertion of your mandrel.
Your neck tension is extremely critical in order to retain your bullet jump dimension you may even have to go smaller in order to keep it constant.
I have found that neck tension will vary from manufacturer to manufacturer of brass shell cases. This is partially because of the brass itself. The construction and composition of brass will be slightly different more so with brass manufactured overseas ( Norma & Lapua ) to name a few or military brass, or range brass itself which could be a mixture of anything and everything.
In essence what I am trying to say is that experimentation on your part is what you must perform in order to just find that optimal setting.
Either your expansion or reduction mandrels are tapered and do not require a lot of downward pressure to obtain the desired results.
The key here is to be constant and apply the same amount of pressure all the time.
OBTW If you have a case neck that has been damaged by striking a table or cement upon extraction and now will not fit into your FL busing die ,either mandrel can repair said case neck so that it is usable.
Just my 2 cents worth!

 

[antelopedundee]

With regards to neck turning, after using a bushing alone handloaders see a reduced runout on the neck and sometimes assume that the bullet should now be concentric with the bore. But what about the concentricity of the inside of the neck? Isn't this the most important area that should be concentric? This is the part that "should" hold the bullet concentric to the bore.

Although I'm always learning and will NEVER assume that I know it all, my current method is to use a mandrel to do the neck sizing. I really don't care what the relationship is between the outside of the neck and the chamber. Bullet-to-neck concentricity and tension is what I think is the most important.

But, like I said, I'm always willing to listen to other handloader's thoughts and make changes accordingly.

Some people ream the inside of the neck when they/you end up getting "donut/ring" near the neck shoulder junction. Otherwise I would think that if the mandrel itself is round that it will exit the neck and leave it round and concentric as well. In the past I have seen a few new cases where the neck was knocked sideways a tad and thus would would not be concentric with the bore. If your necks are of uniform thickness, then running them up into a properly aligned die will leave them concentric inside and outside. It's possible to turn your case necks thin enough so that running them into a die would require no expansion afterwards except by the bullet. Never personally took it to that extreme. A moderator over at accuratereloader.com did some testing and decided that neck tension had little or no effect on group size.

 

[Blackhawk]

Some people ream the inside of the neck when they/you end up getting "donut/ring" near the neck shoulder junction. Otherwise I would think that if the mandrel itself is round that it will exit the neck and leave it round and concentric as well. In the past I have seen a few new cases where the neck was knocked sideways a tad and thus would would not be concentric with the bore. If your necks are of uniform thickness, then running them up into a properly aligned die will leave them concentric inside and outside. It's possible to turn your case necks thin enough so that running them into a die would require no expansion afterwards except by the bullet. Never personally took it to that extreme. A moderator over at accuratereloader.com did some testing and decided that neck tension had little or no effect on group size.

Perhaps I need to explain further.
I myself neck turn only virgin brass.
To that end I will wet tumble in steel pin media for 1 1/2 hours after performing the initial deprime F.l. sizing and establishing the correct shoulder bump of - .002" using the caliber specific Redding Body Die and Competition Shell Holder Set.
Next I will dry my brass in a case dryer set at 104 degrees for 1 hour.
Finally I am ready to anneal.
I do this for the following reasons. I want to prevent any residue left over from the neck turning cutting oil that I use from imbedding itself into the brass case necks during the annealing process, where the brass temperature will reach 760 degrees. (determined using High Temperature Templaq)
To that end I start with brass that is as close to pristine as I can get it.
I myself do not object to the slight brownish - blue decolorization that the annealing process yields.
On the contrary it will serve as a visual reminder that these case have been annealed. What does bother me (perhaps a little anal) is the small marks left on the case necks even after turning under power. I have found that wet tumbling and drying before annealing will remove , or almost remove all of these marks.
This to me results in a more esthetically pleasing brass.
After I anneal, I will again run my clean cases through my FL bushing die in order to reestablish the correct neck tension. (remembering that this step is only done one time on Virgin Brass only and this extra step need not be performed again)
I will finish handloading as per the norm , making certain to keep a constant neck tension and jump dimension as I seat my bullets. All this is determined by both the case neck s I.D. & O.D.
Next I post size my completed round and then check my T.I.R. and chambering functionality.
Anything more than .0005" bullet runout is considered by me to be to excessive & will be corrected using my Horandy Concentricity Tool.
My normal accepted runout is .0002" - .0005" after adjustment , and many times no adjustment at all is required using the concentricity tool.
This will allow me the best alignment possible between bullet , chamber , and lands. (circle , within a circle , within a circle concept )
There are many ways to obtain your best T.I.R.
The way in which I do it does not require a case neck reamer, not that it may be needed , I just do not find the need to use one at this juncture. This dose not rule out the fact that latter on I may entertain that notion.
My particular method has proven itself with the low ES & SD numbers that I have obtained via my Magneto Speed V3 during the many hours spent in load development, ladder testing and the completion thereof.
As stated earlier neck tension is only one of the keys in obtaining the most accurate loads possible. However it is one of the most crucial for maintaining consistency as well as accuracy !
Additionally accuracy is not a given it must be created and refined .
Therein lies the beauty of tailoring your handloads for optimum performance and not relying entirely on factory ammunition.
Just my 2 cents worth!
Hope this will help your understanding my why and how's ?

 

[30BR]

...What does bother me (perhaps a little anal) is the small marks left on the case necks after turning. I have found that wet tumbling and drying before annealing will remove , or almost remove all of these marks.
This to me results in a more esthetically pleasing brass...

I use some 000 steel wool on case necks while they are in my drill after final turning to remove or flatten those marks. May save you a step...

 

[Blackhawk]

I use some 000 steel wool on case necks while they are in my drill after final turning to remove or flatten those marks. May save you a step...

Thank You for your response !

 

[Old Rooster]

Just a question.
If you use graphite on the case mouth won't it allow the bullet to move rearward under recoil?
I don't shoot competition,just hunting with a 300 win mag and worry about neck tension not being enough under recoil.
May be a stupid question but it's one that I have had for a long time.I know this thread is older but I have seen and heard of bullets moving rearward under recoil and I wonder if using a bullet lube could add to this condition.
Old Rooster

 

[30BR]

I use a 21st Century arbor press with strain guage to see how much pressure it tales to seat my bullets. If you use a bushing .003" smaller than the diameter of a loaded round, you probably won't notice any reduced seating force. If you are not neckturning with a BR chamber, and seating soft, you are probobobly using about 100lbs of seating force, and I doubt that lubing the case mouth will be the difference between a bullet staying put and setting back. It usually only accounts for1 or 2 lbs of force in my set up and I'm down to about 12 lbs in some applications, and about 40 in others.
When I used the std .002 bushing method as I had before getting this press, my seating forces were off the scale (max reading is 100 lbs.). Adding neck lube was not going to impact that number .

 

[Old Rooster]

Thanks 30BR I can see your point.
I have not used lube on case mouths ever and had thoughts about it but then a bad thing happened.A friend was standing within 5 feet from a man with a savage 99 that flew into pieces all over the range.The problem was cartridge set back is what I heard later so it's been on my mind ever since.
I use a bushing .002 under for my 308 and .003 for my 300 win mag but will try dry bullet lube on next reload session.
I have not used a mandrel yet but will look into one.I'm just wonder about .001 neck tension with a 300 win mag.
Thanks for the reply.
Old Rooster

 

[Bobcape]

Here is a good video that discusses using graphite on necks. It is mainly about reducing ES on big boomers like the .338 Edge. It's interesting. .


Bob