Expander Dies and Cast Bullets

[Clay M]

Just wondered what the consensus on case expansion versus bullet diameter and neck tension.Think about the .45/70. Most expander dies have a plug that measures .454 This is designed with a .458 jacketed bullet in mind.So if you are using a .459 cast bullet,it may scrap lead when you seat the bullet. My question is,what is the ideal seizer plug for say a .459 cast bullet? How much neck tension is really necessary with smokeless powder. I know with black powder you need very little if any.

[TXGunNut]

For the smokeless cartridges I load and the boolits I cast a sizer .003-.004" under the size of the boolit seems to work well.

[smoked turkey]

The process I have used starts by slugging the bore to determine what dia the sized boolit needs to be. I like from .001-.003 over groove diameter. That is not a hard and fast rule but is generally a good place to start. With that I purchase a sizing die to give the required finished dia. The mould needs to throw its boolits from the mold so as to be at least the .001-.003 mentioned above so the sizing die can work. You will note that you may have to compromise on the needed diameter if the sizing die maker doesn't offer the dia you need. You can have the die opened up to the needed dia by any one of the folks here on the forum who do this kind of work. As for the proper amount of neck tension, I make the expander die for the neck about .001 under the above finished boolit diameter. This seems to give sufficient grip on the boolit to keep it from sliding back in the case during recoil and chambering. It also provides the proper tension for proper powder burn during firing.This is my method and works for me. I am sure there are others who use a slightly different method that may work also.

[Clay M]

I guess it may vary from gun to gun, type of action,and even type of powder.For instants you need more neck tension on cartridges that will be used in a typical lever action versus a single shot.Slow burning powder versus fast burning powder.I think the important thing is not to have so much that it shaves or distorts the bullets when seated.

[TXGunNut]

That's true, Clay. What works for me in my gun may work ok in your gun and maybe even Smoked Turkey's gun but he's found something that works better for him. Another thing that occasionally comes to bear here is an unusually loose or tight chamber, sometimes allowances have to be made for that as well. My rule of thumb is that the neck must hold the boolit without a crimp and the case neck has no bulges. If the case neck is bulged it generally means it's also sizing your boolit and it no longer has the fit you're looking for. That generally gives you a little leeway, I like my necks a little tighter than ST but we're only talking about a couple of thousandths, you'll have to find out what works for you in your rifles. I also cycle thru the action and chamber-check a dummy round as a final check.

[Doc Highwall]

My expenders are .001" to .002" smaller then my bullet size that I am going to shoot.

[Clay M]

I read somewhere that with magnum revolvers you need a pretty tight case tension and a heavy roll crimp.This means the bullets need to be hard enough to stand seating with an expander .005 undersize .

[Larry Gibson]

I use Lee 45-70 dies (5 die set from Wolf Trader's) so it was/is easy to make expanders that easily fit into the expander die. The one I made/use with my cast bullets sized .459 & .4615 is .458 diameter. Cases NS'd with a Lyman 45 Short neck size die spring back about .001 but FL sized cases spring back more. Of course neck thickness and work hardening effect how much. That seems the right amount for my cast bullets in my TDs.

Larry Gibson

[TXGunNut]

Could be, Clay. I just measured the expander in my RCBS 45 Colt set and sure enough, it's .449". Works quite well as warm as I want to load it with a firm roll crimp. As boolit diameters get larger I think the difference between case neck and boolit diameter should grow as well, think of the case mouth diameter as a percentage of the boolit diameter, not a nominal unit of measure. A .002" difference for a 30 caliber boolit would probably give about the same result as a .003" difference for a 35 caliber boolit, a .004" difference for the 40 cal and the .005" difference for the .45's, all else being equal...but it never is.

[Clay M]

Yesterday I seated some 350 gr .45/70 bullets sized .459 I used a .456 expander plug. The bullets seated easy without any scraping lead or bulging the cases.They should work well in my Ruger #1.The bore dia is .458 . I don't know if that is enough tension in a tube magazine lever action.

[TXGunNut]

Load up a dummy round and cycle it thru if you're going to use it in a levergun. Recoil could be a factor too, there's no substitute for range time!

[JWFilips]

Well "40Super" on this forum has made all my custom expander plugs ..across the board for cast bullet loading. They were a great price with fast service ( for the Lee expander type) Most run about .002" under boolit size unless I made custom alteration suggestions. At this time I have Custom .32acp, 38 Spec & 357 Mag, 38 S&W, 40 S&W and most recently 45 acp expander that he has made. All work excellently although I'm still first time loading for .45 ACP ( just haven't had the time to get out & shoot) His work is excellent.
I do have to say however that there are a few others here on this forum that can also turn out custom size expanders for lead boolits

[TXGunNut]

Yes, check out the vendor section for expander plugs and custom sizers. Buffalo Arms has done a couple of custom expanders for me. Don't be put off by the "backorder" status, they'll show up in a week or two.

[Clay M]

Another thing to do is pull a seated bullet and Mic it to see if it is the same size as before. Heavy recoil in a lever gun could set a bullet back in a tube magazine. I don't try to make a magnum out of my .45/70 but I do shoot loads substantially hotter than black powder ballistics.