Walk me through mandrel resizing

[AKShooter]

hello

Interested in mandrel sizing. Plenty out there on the dies, etc. But not the whole process. Or that I can find. I'm looking at the Sinclair dies and mandrel for .002.

So let me see if I have it right. Take my fired brass. In my case I prefer a full length bushing sizer, Redding with no expander. Here is where I'm confused. So my bushing needs to be smaller than the .002. So what's best. .003, .004? Then use the .002 expander?? Leaving out trim, lube, etc

Sound about right?

 

[mikecr]

Well depending on chamber clearance/amount downsized, bushing selection can be trial & error.
But if you size down and spring back to ~3thou under cal, then use the expander mandrel(not turning mandrel), you should end up ~2thou interference after expansion spring back.
I wish carbide expander mandrels were offered and at cal, just for this purpose. This would allow 1thou less working of necks.

 

[243winxb]

If your not outside neck turning, an expander or mandrel can be used to open the case neck.

In 6mm the mandrel is .242"

The bushing sizes depends on the case wall thickness.

You want to feel a light drag as the mandrel expands the cases.

I have 3 bushings .270" .269" .268"

I use the expander that came with the Redding fl type S die, when using unturned brass. Lube the inside of the necks. Look for a light drag as the expander pulls thru the necks .

 

[AKShooter]

I mostly shoot turned necks, I've been pretty satisfied using the standard bushing dies. But I have a new 47 with a standard chamber shooting unturned lapua brass. Just noticing a little different "feel" sometimes. Just a little harder or softer. And always like to learn different techniques. Away from home. Sounds like I need to do some measuring.

 

[Richard Coody]

what i reccomend is using a full length sizing die without the expander ball installed to size your brass. A honed forster would keep the brass working to a minimum.

now i have a K&M expander mandrel kit with expanders at .001, .0015 and .002. allows me to vary neck tension like with a bushing die. just remember spring back is just the opposite of what it is with a bushing die.

i like the system. consistent neck tension is much easier to find. all irregularities in the neck are pushed to the outside including any donuts so bullet seating is more consistent. the entire neck is sized along with the shoulder. lots of positive benefits.

 

[Mozella]

Here's my take on the subject. Short answer: "It all depends". If the end goal is a particular (and consistent) neck tension, or what most of us call neck tension (subject for a different argument), then there are several things to consider.

The neck OD after firing will depend on your chamber size and how much spring back you get. Spring back will have something to do with neck hardness which depends, to some degree, on when and how you anneal, or if you anneal at all. Of course, since your goal is a particular neck ID, the bushing you use for neck sizing will depend on neck thickness and that depends on your brass brand/lot and whether or not you turn it.

I use a 21st Century turning lathe, I have two mandrels for each caliber, an expanding mandrel and a turning mandrel. The expanding mandrel is slightly (about .0005" or so) larger so that the expanded necks will ride perfectly on the turning mandrel during neck turning.

I also use an identical spare mandrel for neck preperation on each reloading cycle. My procedure is to use an appropriate neck bushing during resizing which I do after firing since I shoot single shot and keep my brass clean at the range. Then I wet SS tumble and anneal. During the priming stage, I insert the "T" (turning) mandrel (the smaller of the two) down the neck to produce the final neck size and insure that it's as round as possible. This gives me the neck tension (bullet grip) I'm looking for when I seat the bullets.

But if you use a different sizing/annealing schedule and/or you want a different neck tension, by procedure may not be appropriate. For example, you may want to insert the larger "E" (expanding) mandrel depending on when you anneal and what size neck bushing you used. You gotta' do your own measuring and testing. Of course you could fine tune a mandrel to produce a particular diameter to give you just the neck ID you want. Or, you might elect to purchase a set of special mandrels in slightly different sizes but for me the 21st Century "T" mandrel works just fine.

Bottom line: Trying to achieve a particular finished neck ID using a neck sizing bushing is an indirect process depending on your neck thickness. Using a mandrel will, in theory, give you more direct control over the ID as well as helping to make your necks round at the last moment before seating bullets.............. in theory.

 

[Richard Coody]

i assume anyone who is investigating using an expander mandrel for neck sizing is already turning necks and annealing. Consistent neck thickness and the consistency of frequently annealed brass are a prerequisite for consistent neck tension.

I have found that using the mandrel method also is the best way to improve concentricity

 

[KMart]

You have several goals when using the mandrels.
Minimum sizing down of the neck of your cases to reach your desired neck size.
Minimum sizing up with the mandrel to reach your desired neck size.
Move any minor humps and bumps to the outside of the case neck.

It will take some trial and error with dies/bushings and mandrels to obtain what you are looking for.

 

[Mulligan]

hello

Interested in mandrel sizing. Plenty out there on the dies, etc. But not the whole process. Or that I can find. I'm looking at the Sinclair dies and mandrel for .002.

So let me see if I have it right. Take my fired brass. In my case I prefer a full length bushing sizer, Redding with no expander. Here is where I'm confused. So my bushing needs to be smaller than the .002. So what's best. .003, .004? Then use the .002 expander?? Leaving out trim, lube, etc

Sound about right?

You will need to test.
I have recently purchased a 6 mandrel set for 6mm and 7mm from @AlloyTargets .
In my limited test- "listening" to the target, working from my previous neck tension test, just a tickle expanded made a real difference. Very limited testing so far!
CW

 

[brantfredrickson]

AKShooter, I to am considering using an Sinclair Gen II carbide turning mandrel to size my necks. The turning mandrel is .262 which I hope will bring the neck id to .261 with springback. The big question is how to bring the necks down first. The options are a Redding type S die or a honed Forster FL sizing die. I watched the following 65 guys video to try to get an idea on what size bushing or honed FL sizing die I should order:

.
Basically they say to measure your assembled ammunition necks and subtract .004. In the video he shows a 6.5x47 honed FL sizing die honed to .286, but never says his assembled ammunition necks were .290" OD.