What's the purpose?

[bruddah]

I read awhile back to get a body die to bump the shoulder back and use the Lee collet die to neck size.

What does the body die do that a FL die won't?

Does the FL die simply reduce the diameter of the brass ALL OF THE WAY down whereas the body die only touches the shoulder?

What's the benefit of using the body die? Or am I messed up in my understanding of how these actually work?

 

[ChrisGarrett]

I read awhile back to get a body die to bump the shoulder back and use the Lee collet die to neck size.

What does the body die do that a FL die won't?

Does the FL die simply reduce the diameter of the brass ALL OF THE WAY down whereas the body die only touches the shoulder?

What's the benefit of using the body die? Or am I messed up in my understanding of how these actually work?

Collet neck sizing dies size the neck around a mandrel. Collet dies like the M neck sizing dies from Lyman seem to be the way to go, as you can size in steps, so bullet seating is easier. The case mouth is opened to X diameter and then the rest of the die is sized to X-Y., but the mandrel keeps the rest of the neck at one diameter.

I don't use them but guys swear by them, so who knows?

A body die just bumps the shoulders back, leaving the neck alone and then squeezes the case body back down. You would need to use a body die in conjunction with a neck sizing die, either a standard neck sizer, or a bushing neck sizer.

What you really want to do is buy, or borrow a concentricity gauge and start measuring your loaded rounds for runout and if you see minimal runout (<.002") then you're doing fine and maybe you don't have to fiddle with any other 'stuff.'

Chris

 

[BillCh]

It doesn't sound like you're messed up in your understanding at all. You have it correct. The body die doesn't do anything to the neck at all.
Someone might want to use a separate body die and neck die, possibly because of a custom chambering or the like. There isn't any reason for most to not just use a FL die.

B

 

[ZombieMonkey]

A body die is used in conjunction with neck sizers when you need to bump the shoulder back. A FL die does the same thing but will also size your necks. A properly setup FL die is the way to go for many people and can load some damned consistent ammo, don't listen to anyone who says otherwise. No body or FL die will size the case all the way down the entire length of the case. (They can get close, but they do very little down near the case head area)

 

[bruddah]

Ok, thanks for the feedback guys. So far I have only used the Lee collet die on virgin Lapua 308 brass. The necks were already smaller than the mandrel in the Lee collet die, and some galling occurred on the mandrel itself. I had to polish the mandrel about 2-3X to smooth it back out after sizing about 200 rounds. I was only using 600 grit sandpaper lightly by hand so I don't think I reduced the diameter of the mandrel of any consequence.

I'm afraid neck tension might be different on the once fired brass though since it was so tight the first time around. I expect it would be a bit less next time, which sucks cause I've worked up a couple of pretty decent loads with the virgin brass.