The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

i think i understood that

hmmm, sounds like the expander ball is heading for the parts bin then!!

The reason for the expander ball is to cope with different neck thickness you might find across a range of case makes and ages in a single calibre. If there is no expander, you risk undersizing some cases so they won't hold a bullet. Alternatively, if the manufacturer selects the thinnest brass ever likely to be encountered and then throws a bit more in for manufacturing tolerances, thick-walled brass will be so overersized (ie with undersize, too small dimensions) it'll damage bullets on seating. By oversizing everything then pulling it back over an expander ball, you end up with something close to consistent dimensions / neck tension on every case.

In my experience, many die manufacturers have become a bit lazy on this and machine their dies to really overdo the sizing part of the exercise. The result is a great deal of brass working. It's essential to lube the inside walls of the neck or you really punish the case in the expand operation, but better still is to throw the expander bit away as Dromia says and use a mandrel type expander - Lyman M die or the Sinclair / K&M die bodies with interchangeable expander stems (sold as 'expander mandrels' for neck turning, but give a nice light bullet hold for match ammo that is to be loaded single-shot. The Lyman 'M' also has a larger dia. top section and slight taper for cases to be loaded with cast lead bullets - it's use is optional and the dies are normally adjusted to keep that bit out of the case-neck with jacketed bullets. Inside neck lubing is normally needed with mandrel expanders too otherwise they quickly become coated with a brass film, especially on new cases or those that have been chemically, ultrasonically or STM cleaned that takes you back to clean metal.

Then better still, even more so, is a bushing die with the bushing size matched to the case-neck diameters. With neck-turned brass, expansion is no longer needed strictly speaking; in non-turned brass this step should still be used but with bushings selected so that the expander hardly does any work. (Google Redding Type S full length sizing die to get an example of how this works.)

ok, so if you took out the stem, it may or may not size the neck properly for your selection of brass due to different thicknesses of the brass. so if you had already bought say the lee deluxe set (whistles nonchalantly), if you were using new to you once shot brass, would you take the stem out, full length resize, then run it through their neck collet die?

Try it take the stem out run 5 cases through the die seat a bullet in the empty cases then chamber them and see how you get on.
Do the same with another five but then run them through the neck die seat a bullet and chamber them see how you get on.

Personally Id just de cap them run them through the full length die with out the expander prime them re load them take them to the range and shoot them. But you must do what YOU are comfortable with.

I'd measure the inside case neck diameter of 10 the FL sized cases to get an average case mouth diameter and also a feel for the consistency of the case mouth diameter with that batch of brass.

I would then see if the case mouth needed expanding to get the neck tension you require, to do this in this first case I would use a Lyman M die expander and then use the Lee collet die from then on with the mandrel sized to give the desired neck tension. For me using cast boolits 1thou neck tension is what I aim for, although consistent neck tension across a batch of brass is more important than the actual tension so long as it isn't to tight to deform the boolit but tight enough build start pressure.

can't wait to get home and have a play... i hate shift work sometimes. although i do need still need to buy some 303 bullets before i can do too much