Which Diameter NOE Pistol Expander Plug?

[Gray Fox]

I have a new-to-me 1978 S&W 25-2 in .45 acp with .454 throats. Which diameter NOE expander plug would I need to load .454 diameter boolits? If I'm able to Beagle my 452424 mold to get .455 boolits, what plug would I then need? I already have the RCBS .45 AR crimp die I'm going to use. Any advice will be appreciated. GF

[gloob]

I would suggest the 458 x 454.

454 expander size will give 100% neck tension in bullets that are at least 453.

458 flare step will be exactly right for 454 and 455 bullets. Slightly larger flare than necessary on 453 bullets.

[Jtarm]

Small diameter = bullet diameter-.002
Large diameter = bullet diameter+.002

Given a .454 bullet, you’d want .402-.406

[gloob]

In most calibers, that ^ would be pretty fine. But in most calibers, all you are actually getting out of an expander is a mouth flare. And 2 over on the flare is going to leave very little shavings, if any, on most brass (depending on the hardness/annealedness), so long as your bullets are consistently sized.

In 9mm the case is super short and thick and it's tapered. So the case gets thick very quickly, becoming thick very close to where the base of the bullet seats. And the carbide dies 99% of reloaders use isn't tapered to the original shape of the case. It just makes the entire case a cylinder, squishing the case a bit extra, near the base of the bullet.

Then the third whammy is that it's common to use cast boolits 3 thous larger than jacketed. Other than for some milsurp rifles, that is not very common.

So in 9mm, the expander plug is required to do more than flare the case mouth. If you use a 356 expander, the 358 bullet will not be 358, anymore. Pull a bullet from at least a few different of your headstamps and put calipers on it, and you will see for yourself. They might still shoot perfect, but I bet that means your gun didn't need 358 to begin with.

A 2 under "expander" is the right size for a collect neck-sizing mandrel, because the case will spring back out. For proper expander plugs, the case will spring back smaller. 2 under is the norm on expanders because expanders normally doesn't have to actually expand the case. The sizing die leaves it the right size, already. The expander portion of the plug just irons out any dings in the mouth and it acts like a placeholder, so that the flare part is performed concentrically. This is why many cast reloaders use only a universal flare die, with no issue, without even using the stock expander. The ones who do that in 9mm with good results are going to include a lot of powder-coaters. And also the ones who claim you should use 22+ BHN bullets "because the twist rate is so fast" in 9mm and scrub antimony fouling out the barrel every now and then.

If you only shoot your own brass out of your own guns, I suppose it might be possible to set your sizing die to shortstroke and only size it partway, to avoid the case swaging effect. But if you're full resizing and using cast bullets longer than 90 grains, you will most likely experience case swaging in 9mm parabellum.

I've found you retain full neck tension even when the expander is up to 1 thous larger than the bullet. Neck tension is there or not. Either the case is slightly smaller than the bullet and this are fine, or it's not. There's a bit of leeway where one size is nearly as good as the other. At least about a thou's worth. When your neck tension is somewhere in the middle, holding the bullet but not passing the bench press, that is usually because you lost some neck tension in the mouth portion, but have some tension nearer the base.

This leeway is how the die manufacturers can set neck tension (in most calibers other than 9mm) with the sizing die, even though cases aren't exactly uniform. The cases are uniform enough they can meet this tolerance. If you ever make a reload that has poor neck tension caused by the case? You might have tried to resize the case and not expand it... and what did you find? The tension will be exactly the same as before. It was set by the size die, not the expander.

I first suspected the last paragraph was the case by using aftermarket oversize expanders, even using jacketed bullets. Making my own expanders gave me more evidence. Especially in 223, with such a short neck. As long as the step flare was sharp and distinct, the neck tension was either essentially full or none, depending on the size of the expander to the bullet. If the flare step was too gradual, I had neck tension somewhere in the middle. An expander full size on the tip but accidentally ground a bit smaller before the flare step would also work fine, but theoretically the flare might get applied less concentric.

[megasupermagnum]

A lot of that is going to depend on the case. Starline brass was especially bad. An expander at bullet diameter provides a lot of neck tension. The same expander in a Remington case and you could push the bullet in with your thumb. For the most part, choosing an NOE expander that is .001" under your bullet diameter should work most of the time. For .454" bullets that would be the .457"x.453" plug. I don't see much reason not to at least buy the .456"x.452", and the .458"x.454" plugs as well. As stated, depending on your brass and bullet you may want more or less. I never could use an NOE plug, then seat without shaving a bullet no matter what I've tried. That step simply isn't big enough. It should be more like .008" over the plug size. I still have a full selection of them from 30 to 45 calibers, but I also use a real expander in conjunction with them. I use the NOE first, then use something like the Lee universal flare die to put a flare on them.

[gloob]

Doh, I got my threads mixed up and went on a diatribe about 9mm.

Yeah, for 454, 1 under would be great. Personally, I want the flare to be 3 thous over the bullet diameter.

[Forrest r]

1st thing you might consider doing is measuring several cases that have been fired in that revolver. Measure the diameter of the case at the mouth of the case. Then measure the case thickness & subtract the case thickness (2x) from the diameter. This will give you an idea of the "max" bullet diameter you can use in that revolver.

Just because the throats are .454" doesn't mean the chambers will accept a .454" bullet.