When to use expander mandrel in the process?

[axio]

Hi guys, I've been resizing my 308 using an rcbs die, non bushing, using the expander ball. Now that I'm including 6.5 in my setup, I bought a Redding type s die and plan on using a mandrel for the inner neck.

My question is when exactly should I use the mandrel? If the intent is to reduce runout and keep a uniform inner neck diameter right before loading, shouldn't I use the mandrel at the very last step?

So then I'd resize the die, trim the neck, chamfer/deburr, and then run a mandrel down the inside of the neck?

If I do the trimming, chamfer and deburring after the mandrel, doesn't that add to some kind of inconsistency as the trimming and chamfer process may mess with the neck opening?

 

[DrewC]

Use the mandrel after sizing. Then on to the other steps.

 

[spife7980]

I too mandrel right after I size so that theres still lube present and then I tumble before I trim. If youre messing the neck tension via trimming and chamfering youre... doing it wrong.

 

[RackOpsTactical]

+ 3, do it after the sizing. Glen Zediker recommends in his book to raise the ram to place the mandrel into the neck and hold there for a 5 count, then lower back down.

 

[axio]

Ok, thanks, guys! Probably was overthinking how much pressure the neck trimming/chamfer/deburring can do to the edge of the neck

 

[axio]

Also, my old RCBS competition dies for my 308 are NOT bushing dies. If I remove the expander on them and then also use a mandrel, I assume that's still a good thing, right? Just replacing the expander ball process with the mandrel process, correct?

 

[spife7980]

Also, my old RCBS competition dies for my 308 are NOT bushing dies. If I remove the expander on them and then also use a mandrel, I assume that's still a good thing, right? Just replacing the expander ball process with the mandrel process, correct?

Yes, it will just be harder to insert the mandrel. The normal dies will size the neck down way smaller than an appropriately selected bushing. Just takes more force to over come that additional working of the brass. Not really any more difficult that the expander ball getting dragged back out though.

Yes, you just replace the expander ball in the sizing die with the mandrel in a separate second step.

 

[axio]

Awesome, thanks, I definitely appreciate the help. I'll just make sure to keep it lubed

 

[shoot4fun]

I still, most times, use the expander ball instead of a mandrel. I use mandrels when I do neck turning or on a couple dies that do not have expander balls. I know the "drag of the ball across the inside of the neck is, well, a drag but I use Imperial Dry Lube inside the necks. Just my unscientific theory but I really think it helps reduce unexplainable flyers.

 

[918v]

I use the mandrel after dry lubing the inner neck and before charging and seating.

 

[oldnmkid]

I gave up on the expander a while ago. I now use Redding Type S FL Bushing for all my stuff. However, I still use the expander mandrel also.

 

[towerofpower93]

I gave up on the expander a while ago. I now use Redding Type S FL Bushing for all my stuff. However, I still use the expander mandrel also.

To clarify; you gave up on the expander ball, but you now use the expander mandrel?

 

[oldnmkid]

I went from 'factory' bottleneck dies - complete with expander ball - to neck bushing dies, expecting to get better results from sizing. Got better yet I thought I could do better.

Took expanders out first, figuring they were 'pulling' shoulders and necks out of position desired, contributing to sizing issues I was still seeing.

About this time I took up neck turning as much to reduce variances in neck thickness as to get a better handle on consistent neck tension. Same with annealing.

Even with all that attention to uniform necks & shoulders I was seeing inconsistent 'parallelism' in the shape of necks after bushing-die sizing. Most frequently I'd see a very slight bell-mouth where they either weren't being sized enough or were springing back some after exiting the bushing.

What I do now is choose a bushing one or two sizes smaller then use a carefully selected expander mandrel to open necks up at the last sizing step. Haven't felt a need for custom mandrels yet, but have been close.

Lately with a Very Short Necked wildcat I built this year (284INCH) I'm finding more neck tension than I'd otherwise use for say 308 Palma loads to work better. So I go farther down for bushing diameter when neck-sizing then use a 7mm expander just barely into necks to bring them back to desired diameter for seating.

Now I understand this may be counter to common practice but for my needs (match sights w/sling for score) it works fine. I lose cases to head stretch rather than split necks, seating force is very consistent & what's most important I trust my rounds to perform well. 49 times out of 50 the nine's I see when my target comes up are what I expect to see after calling the shot being scored. It's not my hand loads....

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The above are not my words but, probably explains it better then I could.