Home Forums Reloading Bullet Casting Neck expander for bottle neck rifle cartridges.

What expander do you recommend for case mouths,/necks on bottle neck cartridges. For example for a 358 win so cast bullets can seat without removing a bunch of the powder coat. I'd also like to expand 308 brass to 358 because I have tons of lake city match 308 brass. I'd like something universal that works with several cartridges.

Thanks,
Bb

I don’t load mass quantities of cast rifle loads. But a couple turns with a closed needle nose plier in the neck will expand the mouth enough to allow a bullet to seat without scraping. Takes a little bit to get the eyeball calibrated but with a little practice it works.

This. I switched from the Lyman M die to the RCBS system. Interchangeable expander buttons for every caliber, in one die body. Mainly I like the style/angle of flair it imparts. That plus the expanders in custom diameters are dead simple to make on a lathe too.

I am so the Lee expander a lot on cast. Works fine.

Maybe mention that the Lee factory crimp die adjusted just right closes them back up nicely in station 4 of my Dillon RL 450b.
F01

I would just use a bridge reamer to provide a gradual chamfer on the mouth of the case. Never had a problem with it and never found the need for a neck expander.

if you have a Lee universal expander look at NOE for a custom one that will fit in that tool and give you neck sizing and neck expanding too.

good quality, inexpensive and works great!

https://noebulletmolds.com/site/product-category/bullet-casting-reloading/expanders/

Sinclair makes two die bodies. One for small and medium calibers, and one for large calibers. These die bodies accept their neck expander mandrels, AND they accept the Sinclair neck turning mandrels. There is a WIDE range of diameters that are available to fine tune just how much you want to expand a neck. I have both die bodies and a fairly large collection of mandrels that suit my needs. The best part is, anybody with a lathe can make a custom sized mandrel for anything.

Lyman M die if seating cast.

I have tried, and used a fired case of a smaller caliber than the case that i am loading.

Such as for a 308 I use a 223 or 243 just as long as the fired case will slip inside the case you are loading.

Tap the base of the case you inserted with a small hammer. It will just put a slight roll on the case you are loading.

Your cast bullet should go in with normal force on the loading die.

I have compared this way to the use of a M die and this works as well for me.

What Blammer said.

To those who alter case mouths (with heavy chamfers or jerry-rigged flairing tools) on necks that were sized/expanded with standard dies designed for jacketed bullets, have you considered that you're probably altering the diameters of your cast bullets when seating them? The reason behind the M die and the RCBS case neck expanding die isn't just to flair the case mouth, it's also to expand the neck ID to comfortably accommodate a cast bullet.

Example: say you're using a .310" cast bullet in a .30 caliber. An expander/flairing plug of .309" is perfect. That .001" under bullet diameter is plenty to grip a lead bullet and won't distort/squeeze said bullet. The neck expander plugs for a .308" jacketed bullet run around .306" and if used that .004" squeeze has got to change the diameter of the lead bullet. (The extent of which is surely dependent on the hardness of the bullet - the harder the bullet the more it'll resist deformation, but at the end of the day the hardest cast bullet is nowhere near as hard as a jacketed bullet.) And if a .311" or .312" bullet is employed (as is often the case in older rifles), that .306 expander ball is an even bigger enemy, and woe if using a really soft plain base bullet and not a gas checked hard bullet on top of all that.

Truth.

When I was messing around with a 325 grain flatnose plain base cast with wheelweights in my 45/70 not only was I fearing altering the diameter, but it was an absolute nightmare just to get the bullet seated straight. Had a buddy with a lathe make me just the right diameter expander plug for my Sinclair expander die body and poof, no more crooked and bulging to one side 45/70's.

Another vote for the NOE "buttons".

I bought a Lyman M2 Expander die over 40 years ago when I started casting lead bullets for my .30-06. Since then I've made a variety of expander plugs from bolt shafts using my poor man's lathe (an electric drill) and a metal file, and a thread cutting die. I not only use these for making a slight bell in the case mouth for lead bullets, but also for expanding case mouths like for making .375 RUM brass from 7mm RUM cases.

Darn nice work! The ones I make in a lathe don't look any better.