Expander Mandrel Size?

[Kswhitetails]

Sure. Looking at your numbers it looks like you want a .287 bushing. You get any neck thicknesses off your brass? That would help confirm, though, your neck is definitely generous. Annealing would be a tremendous benefit for your situation.

(Ignore Klem, he skips important stuff all the time, we just let him go...) HA! Cheers, Klem.

[Klem]

Yea, that's what I was afraid of. I guess it's true what they say. Buy once, cry once. Im considering a redding type s die. With my chamber though that would mean a jump of about .014 to get .003 neck tension? Is that possible with these bushings?

Cs,
Unsure what you mean by .014 jump will give .003 of neck tension. Jump and neck tension are mutually exclusive and controlled by two different dies. Jump is controlled by how deep you seat the bullet and neck tension is about how much you squash the neck in when sizing. You vary the amount of neck tension with different bushings in the S sizing die, while jump is controlled by screwing in and out the seating die.

With an AR the mag length is almost always the controlling factor in jump, and in that you don't get to choose the jump. The upside is, having to seat the bullet to fit a mag you end up with plenty of surface area gripping the bullet which is what you need in an auto loader, and it makes for more consistent tension.

What bushing you choose will depend on the neck thickness of your brass and the amount of springback. KS' .287 sounds about right, I use an S die for 6.5x47 bolt gun and it is .288, but it is a bolt gun.

[Cs22]

Yes, sorry Klem. I was using the phrase jump meaning going all the way from .300 to a .286 bushing which would be .014 difference. I wasn't thinking and forgot jump was also used to describe seating depth from the lands. I was actually wanting to make sure that big of a spread was possible with a single bushing considering my chamber size?

[Klem]

Yes, not only possible but you are already going much more with the Lee die (.021"). You want to stretch and squeeze brass as little as possible to maximise case life, while producing reliable, safe ammunition. Squeezing the neck .014" is a lot better than .021".

[centerfire]

Yes, sorry Klem. I was using the phrase jump meaning going all the way from .300 to a .286 bushing which would be .014 difference. I wasn't thinking and forgot jump was also used to describe seating depth from the lands. I was actually wanting to make sure that big of a spread was possible with a single bushing considering my chamber size?

Don't buy a bushing die...problem solved.

[lazyengineer]

Personally, I like Mandrel dies. I like running a bushing die for sizing, and then a mandrel die right before seating, to assure uniform neck internal dimensions. I used to use Lyman M-dies, which I sometimes still do, but have found their mandrals are a bit narrow in Diameter; and yield pretty tight neck tension, so have now switched to a Sinclair mandrel die for 6.5 use.