Revolver case neck size for cast

[Chill Wills]

We talk a lot about the need for having the revolver throats the correct and same size for accurate shooting.
The die sets we have available, which are some engineer's idea of a compromise between jacketed and cast and the various gun manufactures may or in some cases, may not be a very good fit.

What in your experience would you think would be the best delta between correctly sized bullets and the case receiving it?
Assuming lead alloy hardness in the normal range we most use, not dead soft or crazy hard, would 0.002" or 0.004" be the range? I know many of you have done as I have, by seating a measured bullet, pulling it and remeasuring it to find it has been resized by the overly small case neck produced by the die set expander.

I have been making steel replacements to screw into my expander bodies and like how this works out but I have not done exhaustive tests to have a strong opinion on what delta may be best.
The picture I have loaded up is one for a 45-70 but shows the die relationship.

[Nobade]

Same thing I do. I think almost all my die sets have custom parts in them. I'll usually go for .002" interference on most stuff except for paper patched, then it's a slip fit.

[georgerkahn]

We talk a lot about the need for having the revolver throats the correct and same size for accurate shooting.
The die sets we have available, which are some engineer's idea of a compromise between jacketed and cast and the various gun manufactures may or in some cases, may not be a very good fit.

What in your experience would you think would be the best delta between correctly sized bullets and the case receiving it?
Assuming lead alloy hardness in the normal range we most use, not dead soft or crazy hard, would 0.002" or 0.004" be the range? I know many of you have done as I have, by seating a measured bullet, pulling it and remeasuring it to find it has been resized by the overly small case neck produced by the die set expander.

I have been making steel replacements to screw into my expander bodies and like how this works out but I have not done exhaustive tests to have a strong opinion on what delta may be best.
The picture I have loaded up is one for a 45-70 but shows the die relationship.

Definitely not the brightest lamp in the fixture, I may be "missing" your question a tad -- albeit it is a good one. The two criteria I've focused on are: 1/ the size of the bullet, and 2/ the spring-back of brass. The latter is why I've gone kind of OCD vis annealing ;). If the brass is work-softened to the point of zero springback, no matter what the dimensions are of the case -- recoil (e.g., in a revolver) from previous shots will surely move the bullet! Hence, properly annealed brass in which an appropriately sized bullet -- generally hoped to stay in place until its fired with a Lee Factory Crimp Die -- is what I do.
I apologize, again, if I missed the boat on this one... BUT -- I've reckoned diemakers seek manufacturing to SAAMI specs, and am under the (maybe stupid?) assumption that the higher quality (or at least, higher-priced :)) ones are better in this regard.
geo

[Bass Ackward]

The correct case neck tension? That’ll get you some different answers. �� There is none really because of variables. Brass varies by thickness. Bullets vary by bearing length. Short for caliber need as much as you can get. Which is one of the reasons why one guy complains about unburnt powder with a certain powder and another doesn’t. Elmer liked .010 (no typo) for his 429421 / 2400 load. Makes you wonder if he was worried about brass sizing his bullet.

[Hick]

Interesting question. I like my revolver bullets very tight in the case, so I only expand the mouth just enough to let the bullet start-- then let the case size down the bullet if it wants to. All my bullets of choice have a nose that is full diameter-- so that engages the rifling fine and seals the bore even if the base is sized down.

[DougGuy]

if it's an autoloader, 45 acp, 9mm, etc, one test is pulling a boolit and mic'ing it, the more important test is the pushback test. After you load and crimp a round or a dummy, press the boolit against a firm surface and press on the case head see if you can push the boolit deeper in the case. If you can, that one failed the neck tension test, and the crimp test. If you can't and the boolit measures acceptable after you pulled it, then good to go.

Case neck tension and crimp go hand in hand. One typically does not work well without the other.

If you can see a little distortion in the outside of the case where the boolit is seated, neck tension is what causes that. That, is a good thing, provided you can chamber the rounds without issue.

Some people see this and think OMG I got to fix that so they go waste money on a carbide ring type FCD. That smushes the boolit in the case so the outside of the case is smooth and well, factory looking, and once out of the fcd, the brass case springs back, pretty much negating any neck tension you may have had.

[20:1]

The correct case neck tension? That’ll get you some different answers. �� There is none really because of variables. Brass varies by thickness. Bullets vary by bearing length. Short for caliber need as much as you can get. Which is one of the reasons why one guy complains about unburnt powder with a certain powder and another doesn’t. Elmer liked .010 (no typo) for his 429421 / 2400 load. Makes you wonder if he was worried about brass sizing his bullet.

I'll bet that the though never entered his mind. He did seem to prefer a harder alloy than you see nowdays. IIRC he normally ran 16:1, which is right at bhn 11, but Elmer also used the original design steel sizing dies which are slightly tapered inside, the base area gets little to no sizing at all. It's sort of like neck sizing. Most of todays sizing dies with carbide and nitrided steel inserts size the cases down far too much and they work harden between firing, sizing, and case mouth expansion which eventually causes case mouth cracks.

[Chill Wills]

Thanks for the responses. I certainly need to do my own homework.
I am going to try different size expanders to get a better idea at what point the small expanded cases reduce the diameter of my bullets. For what it is worth, my common handgun alloy runs 11-13 BHN.

At this time, I do know, it does no good to have correctly sized cylinder throats only to reduce your carefully sized bullets in the seating process.

Carefully honed throats and bullets matched in diameter can be reduced a few thousandths in the seating process with the small expanders provided for use with jacketed bullets.
I have pulled apart a number of my reloading dies and measured the expanders. Most are very small and number run all over the place. However, I have yet to test under-sized bullets against correctly sized bullets on paper targets to know how much difference it may make.

[Bass Ackward]

Food for thought, does it matter the type of dies? With a tapered case, in order to seat the bullet, the base has to enter / pass the smaller diameter at the mouth to get back to the enlarged portion.

[Chill Wills]

Food for thought, does it matter the type of dies? With a tapered case, in order to seat the bullet, the base has to enter / pass the smaller diameter at the mouth to get back to the enlarged portion.

I don't follow. I think the section of the case that holds the bullet is a cylinder. As the case walls get thicker back near the rim, the inside reduces in diameter.

[Bass Ackward]

Seems kinda one of the mysteries to cast. When you set off the explosion of several thousand pounds of pressure your base expands, expanding the brass out to the chamber walls and then moves forward opening the crimp and gets it’s first down sizing with the taper in front of the throat. So if it expands out to the size of the chamber, (are all chambers exactly the same size if the throats weren’t) does the starting diameter of the base really matter other than for tension? Well, if the gun says it does, it does.

[Chill Wills]

You didn't address the tapered cases statement you made in post #9. Am I missing something there?

The question of obturation with smokeless powders...
With black powders, it is a given with alloys up to a certain BHN and less to none with harder alloys.

Do our revolver alloys obturate as well? Maybe with the same time/pressures as BP. What powders have those characteristics? What I think I know about Smokeless powders is the pressures of most of our sporting powders do not replicate BP. But, I don't really know that for sure. What facts can you provide on that subject?

The crimp! Yes, fired cases still show crimp! That is a puzzle to me. Does the crimp size the bullet smaller on the way out? Or, does the crimp open fully or almost fully and then spring back?
Most of my experience where I think I really know what is going on with cast is with uncrimped rifle cases in singleshots. I have lots to learn about revolvers.

[Jtarm]

For dies I run the Lee universal flare with the NOE expander or an RCBS with a Buffalo Arms expander.

I follow the -.002/+.002 rule. Sometimes that doesn’t work. The one gas-checked bullet I load requires -.001/+.003 to get the bullet started straight in the case.

I recall Skeeter Skelton writing that his initial .44 magnum handloads slipped crimp, so he had his expander turned down to .423.

How he squeezed .430 cast bullets into a .423 neck without damage is a mystery to me.

[20:1]

I'm a bit surprised that nobody has brought up Lyman "M" expander dies.

[DougGuy]

With a tapered case...

We were discussing revolvers, I took it to mean typical 44m, 45 Colt, 9mm, 45 ACP, etc, no wildcat calibers. These are straight walled cases, they don't taper they are parallel, the chambers are tapered for easy case extraction.

[Chill Wills]

I'm a bit surprised that nobody has brought up Lyman "M" expander dies.

The picture in post #1 is basically that but in any size needed. The Lyman is some unknown diameters by marked caliber. They are often better than the stock expander.

I make these to the exact 0.001" wanted.
The two diameter cylinder expander omits the flare, which is un-needed if the larger part of the expander is about 0.002" above the bullet to be seated.
I have been making these for my BPCR match competitors (singleshot rifles) and have not made the handgun expanders for anyone else.

[Bass Ackward]

If you have dies that put a taper on the cast or you neck size, you still have to enter a smaller neck diameter before you get back to the larger diameter portion of the case. So if there is gonna be sizing of the base, it happens anyway. Any clearer?

[Bass Ackward]

The comment was to older steel dies vs carbide ones today.

[Chill Wills]

If you have dies that put a taper on the cast or you neck size, you still have to enter a smaller neck diameter before you get back to the larger diameter portion of the case. So if there is gonna be sizing of the base, it happens anyway. Any clearer?

I think the expander, being a cylinder, makes a cylinder of the inside of the case mouth and the full length it travels, regardless if somehow the case started in some other configuration.

[Bass Ackward]

True, if your sizer takes the case down far enough. Personally, I use a Lee universal beller just to allow the bullet to start and let the bullet perform that task for “pistol” cases. I run slower powders, so case neck tension is paramount for me. Someone running Bullseye would most likely have a different opinion.