Neck turning vs Bullet seating pressure

[Brent]

I'm heading to bed, I'll explain in the morning. It has to do with how much the brass will over run the bushing diameter and end up smaller than the bushing I.D.

My wifes going to kick my *** if I don't hang up.

 

[dbhostler]

I've used Sinclair tools for years, is a K&M tool better? Does K&M have a web site or a contact number?
db

 

[Darryl Cassel]

Hello

The Sinclair is an excellent neck turning tool as are the K&M and the old Hart with the Mic attached. The Hart is very desirable when you can find them.
The K&M is right there with it though.

Here is the K&M phone number---717-292-3175

[ 11-30-2003: Message edited by: Darryl Cassel ]

 

[Brent]

HoytemanPA,
In my experience with using bushing dies and "no" expander, I've found that if you have, in your case for example a fired diameter of .344" and maybe turned down to 343" for a good clean up, you'll find a .335" bushing will produce a neck diameter of as low as .332" - .333", not the .335" as one would expect.

I got a .335" and a .334" bushing for my 300 ultra, the .334" bushing was sizing them down way too far and is never used.
The .335" bushing was still sizing them down far enough, it forced me to turn the necks unless I wanted to spring for another bushing. I was thinking I'd turn them anyway, but now I had to in order to use the .335" bushing. My necks are .014" thick and I get .002" tension using it now. Incedentally, I get the same tension in my Redding non-bushing FL die without an expander as well, which I had to revert back to useing to elliminate the RO my chamber was producing.

When I used the .335" bushing before turning the necks, which was what I came up with using Reddings "previous" recomendations on how to determine the size to use, I had way over .005" neck tension!

Redding has since revised their suggestion of .002" - .003" under loaded diameter to .001" - .002" under I believe. This still would not have worked on my rifle, the neck of the chamber was so large, .340" -.345" I think. I think .337" - 338" would have been the smallest I could have used.

What happens when you try to step a neck down by the amount a factory chamber forces you to do, is the neck will actually over shoot the I.D. of the bushing (because of the entrance angle) when running it up into it by enough that the spring back is not enough to bring it back to the bushing I.D. the rest of the way up the bushing.

On a tight neck chamber (.002" total clearance), such as the 30/338 Lapua I'm loading for, the case neck will follow the bushing so tight up its I.D. it will actually spring back enough it is actually .0005" - .001" larger than the bushing I.D....

These factors are not really layed out, but the more you use them I'm sure you'll see the close to the same results. Hardness of the necks will vary the sizing of them too, as you might expect.

For a factory cut chamber, as a starting point I recomend a bushing size equal to the loaded diameter of the cartridge, that's for .002" - .003" neck tension.

For a tight neck chamber, .001" smaller than the diameter that would provide your desired neck tension.

I think that's about as close as one can get on the first guess, expect that you may buy anothe bushing if it's a thou off from what you figured.

IMHO, it's a much better representation than simply buying one .001" - .002" smaller than the loaded diameter as Redding recomends, which doesn't take chamber diameter into account at all.

 

[Whitetail Hunter]

Brent,

My fired case diameter is skecthy at best. The fired case is tapered. Using a mic measuring the the full diameter of the mic shaft the case measures .347 At half the diamter of the shaft it measures .346 The very top of the neck measures .340 .002-.003 sounds good beacuse I don't want them to move due to recoil and jam. I guess I should only need one shot anyway

 

[Whitetail Hunter]

4mesh063,

Would you recommend a Lee collet die over a bushing die? Why or why not? I'm trying to get a feel as to what is the best route to go. I know on my FL dies i get 5 rounds out of 20 that are .001 to .002 runout which is terrible. The rest are generally .004 to .005.

 

[HoytemanPA]

Brent,
Thank You for the clarification. I fully understand now, ( following a little more hands on). I had based my bushing selection solely on what worked for me with the Weatherby. The fired neck size in that one is .337, now that I know that number does mean something. The loaded round measurements on the Norma Brass that was fully turned is .333. I purchased the .332 bushing for it and the resized case necks are actually .3315-.332. ,without the use of the inside sizer button, causing the reason for my misunderstanding. It followed the finished bushing size to a tee. Just got lucky I guess having a chamber in between the huge rem chamber and a tight neck custom.

Now the Rem Brass, Rem chamber does show drastically different results that follow exactly as you further explained. With the larger chamber dimensions, and the inside sizing button removed, the finished size for the neck ran through the .335 bushing is actually .332, I tried seating with that extra tension and that just ain't gonna work. So I stuck the inside neck sizer button back in the die and it came back out to .335. I guess either I got some more turning to do, keep on using the inside sizer button, or go back and reread the rest of what's been posted and try to decipher it. Is there any major disadvantage to using the inside button?

I guess I was missing something.
Thanks alot,
HPA

 

[Brent]

Craig,

Are you sure there is .007" difference in diameter along the neck? That seems quite a bit excessive, does you're mic read to the ten thou, and might it be varying from .3400" to .3407" if it does, 7 ten thou? This would make more sense, not to say yours aren't 7 thou smaller at the mouth, cause they just might be. Just a thought. For these type measurements, my dial caliper works just fine. The one measurement that is sometimes is impossible to get with a caliper, even for just comparison purposes is, neck thickness. Sometimes the brass will do almost like your measurements suggest, almost roll, or taper inward near the mouth, so trying to measure somethings thickness that isn't parelell on the inside and out just measures larger than it really is. You can measure it right at the case mouth with fairly descent results, just that the deeper you try to measure thickness, the larger number you get when that's not really the case. A ball mic is the only way to go for the deeper measurements, or seat a bullet and take an outside measurement, and a caliper works fine here for relative comparison purposes, and I'm sure a couple three ten thou resolution isn't a stretch either.
At any rate, before and after seating outside diameter measurements up and down the neck will tell you what amount of press fit you're getting along the necks length.


Hoyteman,

You're right, I don't use an expander ball. I should have said that in the beginning.

I had to use it on the cases that sized down too far like the ones you did, oh, and I swear they were altering the headspace it had so much resistance, like to jerk the necks right off of them!!

So I didn't have to use the expander after that bout, I turned the necks down just enough that I'd get .003" press fit without the expander using that bushing, that's when I found I got the same press fit when running them through the FL die too, with no expander. Turned out that was just a bonus I hadn't expected.

It followed the finished bushing size to a tee.
Just got lucky I guess having a chamber in between the huge rem chamber and a tight neck custom.

I think you hit the nail square on the head there. That's about where I'd expect it to work about right also. The reamers that are held to a little tighter specs should all work about like that I'd figure. My dad has a couple chambers just like that, .003" to .005" total clearance with loaded ammo. I'll have to ask him what he's getting as compared to his bushing size.

More than anything, I just don't like using an expander, although it's said RO can be made worse using one, that's not the real reason I don't. I just haven't found any difference with or wothout, but I don't lock mine down either, I just let it float. That may be making a difference. They're never in the center when locked down on any of my dies, so I figure it would be better to leave it loose to let it center as a drew the neck back over it.
The main reason I don't use it is, if I have to, I'm obviously sizing it down farther than I need to, thus working the neck more than's needed. That, and I've never liked getting lube inside the neck, or cleaning the stuff back out with a patch and brush. The carbide balls work a little better, but I lubed cases using them too, just went a lot smoother still. If I tumbled or vibrated brass to clean it it probably wouldn't be a big deal keeping the necks consistant. A little more lube left on this neck than that one didn't instill confidence in consistant neck tension. I ain't lookin to will a beauty contest with my brass, so they get the lube wiped off of them and that's clean enough for me. Vibrating them to me is a complete waste of time and effort. Powder build up on the inside of the case, with the powders I use, are totally insignificant.