Mandrel v bushing dies on case necks?

jackie schmidt said:
There is no way a single pointed tool finish will be as smooth as the extruded finish in a case.
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Absolutely. A reamed neck can also provide a beautiful finish. In my day job, I had access to fairly high resolution microscopes. The finish on even the best single point bored case neck I.D. we did looked like a nasty Slinky :eek:. I'm starting to tread on ground where real machinists and precision craftsman live, though. I want to make sure people understand I'm not one.

jackie schmidt said:
Another fallacy is.....”you will never get a donut”. The donut is formed by metal moving at the neck shoulder junction after repeated firings and resizing. When you turn cases with a standard neck turner, they start out with no donut, as the entire ID of the neck is expanded by the turning mandrel. But, regardless of your best efforts, if you fire it enough times and full length size, a donut will form.
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Yep. ;)

Good shootin'. -Al
 
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Al Nyhus said:
Gene, that's exactly the issue. Standard chucking reamers more than up to the job, as are some of the micro boring bars. Stan Ware made what he termed the D.A.P. tool (Dumb Azz Proof ;)) to support the neck. We also looked at chucking reamers that piloted through the flash hole but that ended up being a dead end.

Getting the untouched necks straight with the body before starting can be challenging, at times. Lightly stress relieving the neck/shoulder area helps big time.

Hope you get it worked out. I'm pretty much a dirt clod hack but got it done, thanks to Stan.

Good shootin'. -Al
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Thanks for the response Al!

GsT
 
GeneT said:
Thanks for the response Al! GsT
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Gene, The D.A.P. tool :D is basically a counter bored 'cap' that fits over the round stock that holds the case....like what a Wilson Case Holder would look like if it was shortened to expose the entire length of the neck. The D.A.P. has three set screws to hold it to the outside of the case 'holder' and accepts a standard neck bushing. Use a neck bushing that fits the O.D. of the unturned neck nicely and go in with the reamer. That's why the necks have to be straight with the case before starting.

In all honesty, I did some without the D.A.P. and while they showed just a skosh of runout, once they were sized and fired, the runout was as minimal as the D.A.P.- done cases. Certainly, this has to do with the amount being removed from the neck I.D., which was minimal in the case of the .30BR's. On the 30BR's, before inside neck reaming, I sized down the 'lump' at the new neck/shoulder junction to the diameter of the unturned, but expanded, neck above it. This left a donut inside. The reamers have long tapered section before the major diameter and this nicely removed the donut without tweaking the neck off axis. The 'lump' shown, below:

1XqzekLl.jpg


The same process was used on the 30 WolfPup (below) Stan and I developed for HBR/Hunter competition. These are my 117's on a 1.00" jacket which puts the base of the bullet well below the neck/shoulder junction, neck length is .085. The neck I.D.'s had to be perfect for this deal, but for other reasons...;)

VpBo0QSl.jpg




Hope this helps. -Al
 
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Check out mandrel only makes concentric not cutx

jackie schmidt said:
The problem I see with that setup is the finish inside the case neck. There is no way a single pointed tool finish will be as smooth as the extruded finish in a case.

Another fallacy is.....”you will never get a donut”. The donut is formed by metal moving at the neck shoulder junction after repeated firings and resizing. When you turn cases with a standard neck turner, the start out with no donut, as the entire ID of the neck is expanded by the turning mandrel. But, regardless of your best efforts, if you fire it enough times and full length size, a donut will form.

The person in the video obviously put a lot of thought and time into this, and the machine is fast. but it looks like it would create more problems than it is supposed to solve.

Being a Machinist, Here is the way I turn necks using my Monarch EE. It does exactly the same thing as a hand turner, just a lot quicker.
https://m.youtube.com/watch?v=xykoVHY_Lkc
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:cool:
 
I'm thinking we should mebbeso start a Go-Fund-Me for to get Jackie a bigger lathe...... I'm wondering just how much flex he's getting when he loads into them gnarly casenecks....
 
Hey I just noticed something else.... this is the first vid or pic of Jackie where he don't have bandaids (or duck tape) on something or another.... ain't even got a black nail there man, looks like you been being careful!
 
Al Nyhus said:
I experimented with the mandrel method when shooting the 30 WareWolf (basically a .165 short 308 Lapua) my HBR gun. And no...it was not with any sort of Lee collet die lash up. ;)

Initially, it seemed to show some slight accuracy improvement.

What I was actually seeing was that the mandrel was a bandaid for how bad the necks I.D.'s were. They were round but also tapered. Like this, top to bottom (exaggerated, if only obviously :eek:):

M7t5hgah.png


After finding that, I made the neck I.D.'s perfectly round the on my fired cases and tested that. The results on previously neck turned cases was a train wreck. But on new cases, where the neck I.D.'s were made perfectly round before outside turning....the accuracy was better than it had ever been especially at 200 yards. Beggar 10's @ 200 became solid 10's and the 'almost-a-10' 9's @ 200 became beggar 10's. :cool: Grand Aggs are won or lost @ 200 and the Grand wins came with more regularity after that.

Since that, inside case neck work became part of my BR case prep routine, carrying over to the 30BR cases and even to the 30 WolfPup with the .085 length neck.

Does every case need it? It depends. If necking up or down, I do it. I did it on my 6PPC with the 220R cases and found nothing with both barrels. But on my 22BR, there was an improvement. My 20 Practical (necked down Lapua 223 cases) shows the same characteristics. I haven't fixed them yet, but I will and will test them next Spring.

I don't compete any more in registered BR tournaments but still consider the case neck I.D.'s to be a critical part of case prep if you're looking for BR level accuracy.

Good shootin'. :) -Al
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Great info, Sir. Thanks
 
jackie schmidt said:
The way most shoot the popular Short Range Benchrest rounds, bullets never get any where near the donut that will, regardless of our best efforts, form at the neck/shoulder junction after several firings.

That is why I consider it a non factor.

However, in disciplines where longer bullets are used, especially in a shorter throated chamber, it can be a huge issue if the shank of the bullet gets into the donut.

The best solution is to throat your chamber for a specific bullet so this never occurs.
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Good point, Sir. Thanks
 
Here's the way I turn necks (Lapua Brass 6ppc)

I mount a expanding mandrel in the set-true chuck and dial the thing to zero. I made a pusher that goes in the tail stock and use it to push and expand the case. The mandrel drives the case because it's a tight fit. I turn the brass with a single point tool. The pusher has an extraction tool that fits in the groove of the case to pull it off when I'm done. The necks come out perfect and there is no scoring on the inside because the case never turns on the mandrel. No heat issues to deal with. I have stops set on both sides of the carriage and a dial indicator on the tail stock so everything repeats.
The pusher has a pilot to fit the primer pocket. It's a PITA to set up but works well.

Richard
 
So, Jackie..... those are FIRED cases and they spin inside the fixed shellholder?

I just realized what you're doing. Friggin' BRILLIANT, I'd a' never thought of spinning the case with it captured, but essentially free with several thou tolerance.

I have a setup where I insert and support the tightly fitted mandrel COMPLETELY BAZZACKWARDS of what you're doing. which essentially accomplishes the same mechanical functions but....gotta' drive the case etc....


but'chyoo'


BRILLIANT!
 
Richard said:
I mount a expanding mandrel in the set-true chuck and dial the thing to zero. I made a pusher that goes in the tail stock and use it to push and expand the case. The mandrel drives the case because it's a tight fit. I turn the brass with a single point tool. The pusher has an extraction tool that fits in the groove of the case to pull it off when I'm done. The necks come out perfect and there is no scoring on the inside because the case never turns on the mandrel. No heat issues to deal with. I have stops set on both sides of the carriage and a dial indicator on the tail stock so everything repeats.
The pusher has a pilot to fit the primer pocket. It's a PITA to set up but works well.

Richard
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Richard, I always turn a new mandrel every time I decide to turn necks. But then, I always have a lot of material laying around.

I usually do 100 at a time. As you can see, I have a mist cooler spraying on the mandrel to keep the set up cool and to lubricate the tool.
 
Similarly...

Fred Bohl said:
I've waited to see were the replies might go before my own reply.

My simple answer is yes I have. I neck size using a bushing that produces a neck of slightly smaller ID than desired (0.001 under) then an expander die to open the neck to the desired ID size. Testing over the 4 cartridges I load for shows slightly smaller groups for those mandrel sized than those just bushing neck sized. Note that the reduction in group size is very small but for me it is worth the added effort.
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I've tried it in several different scenarios too. Where I'd normally use a 257 bushing, for example, I used a 256 bushing and resized the case body too. Then ran them through the expander mandrel that is in my K&M neck turning kit.

The results were lower and much more consistent seating pressure for all cases. The results on the target showed that bullets that are seated deep into the neck or slightly more were consistently accurate for 300+ yards such as 90-103gr bullets from a 6br or 6xc. For the short range 100-200yd 6ppc or 6 Grendel did NOT show any dramatic and positive affect towards smaller groups on a consistent basis. In fact one 6ppc the groups opened WAY up, and on another 6ppc I have they stayed pretty much the same but NOT better.

It's worth a try for me just because I learned something from it. JME. WD
 
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WyleWD said:
I've tried it in several different scenarios too. Where I'd normally use a 257 bushing, for example, I used a 256 bushing and resized the case body too. Then ran them through the expander mandrel that is in my K&M neck turning kit.

The results were lower and much more consistent seating pressure for all cases. The results on the target showed that bullets that are seated deep into the neck or slightly more were consistently accurate for 300+ yards such as 90-103gr bullets from a 6br or 6xc. For the short range 100-200yd 6ppc or 6 Grendel did NOT show any dramatic and positive affect towards smaller groups on a consistent basis. In fact one 6ppc the groups opened WAY up, and on another 6ppc I have they stayed pretty much the same but NOT better.

It's worth a try just because I learned something from it. JME. WD
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Great info. Thanks
 
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