Custom reamers. . .what is involved?

[bigngreen]

I think that would be a good project to under take, first step I'd take is cheap 7 RUM die and cut the bottom of till you push back the shoulder to the correct neck length your wanting and see how well it forms, if you form a major doughnut or need trimming so you
know where you need to be at with your neck diameter and hit the reamer spec first try. I always start with that anyway, I've ran into things where I find out the parent case won't respond to the forming sometimes but I think what your doing should work very well. I definitely think you'd have a good platform for launching the 195 Berger

 

[Edd]

I think that would be a good project to under take, first step I'd take is cheap 7 RUM die and cut the bottom of till you push back the shoulder to the correct neck length your wanting and see how well it forms, if you form a major doughnut or need trimming so you
know where you need to be at with your neck diameter and hit the reamer spec first try. I always start with that anyway, I've ran into things where I find out the parent case won't respond to the forming sometimes but I think what your doing should work very well. I definitely think you'd have a good platform for launching the 195 Berger

I don't agree with that strategy. A 7mm RUM die will have a 30° shoulder. You only need to push the top of the shoulder back about .015", you know you can do that. What he needs is a form die that will push the neck shoulder junction back to form a 40° shoulder and push that 40° shoulder back about .015" in one step. A form die will cost $105.

 

[bigngreen]

I don't agree with that strategy. A 7mm RUM die will have a 30° shoulder. You only need to push the top of the shoulder back about .015", you know you can do that. What he needs is a form die that will push the neck shoulder junction back to form a 40° shoulder and push that 40° shoulder back about .015" in one step. A form die will cost $105.

I've had better results pushing the shoulder back at the original angle to gain the neck length then blowing it out to 40 degree and remove the taper in the case wall, doing it the method you described I've found I don't get as good of a transition at the shoulder neck junction but it depends on the brass which is why I suggest a cheap trial run.

 

[Edd]

I've had better results pushing the shoulder back at the original angle to gain the neck length then blowing it out to 40 degree and remove the taper in the case wall, doing it the method you described I've found I don't get as good of a transition at the shoulder neck junction but it depends on the brass which is why I suggest a cheap trial run.

Sounds like you've never tried it the way I described.

It is much easier to push back a portion of the shoulder than it is the whole shoulder and you will get the same result on the neck shoulder junction either way.

 

[bigngreen]

Sounds like you've never tried it the way I described.

It is much easier to push back a portion of the shoulder than it is the whole shoulder and you will get the same result on the neck shoulder junction either way.

You would be mistaken, using the method you described with some brass is exactly why I started on some cases pushing them back at the parent case angle. In some cases just hitting it with the 40 degree will not flow the brass through the shoulder neck junction it just compresses it in the neck shoulder junction creating another set of issues. AGAIN not all brass does this, I've just ran into some that does and that is why I start the process with making sure I can form the brass before ordering reamers.

 

[Mikecr]

It will take considerably more than 15thou of pushback to reach .355 neck length, as the parent neck length is only .287 (I get 68thou needed).
I think it would take a form die at a low shoulder angle to prevent collapsing of the shoulder, and then fireforming to finish. You will have a huge donut, and you'll probably wish to turn this out before the fireforming. You can use a standard die to get through fireforming and then send formed cases off to JLC Precision or another custom die maker for a sizing die. I don't know who the best die maker would be for a seating die, if threaded. If using Wilson, you could have a blank seater die chambered along with your barrel(for bullet seating) using the same reamer.
The reamer/chamber is easiest in planning here.

 

[Edd]

It will take considerably more than 15thou of pushback to reach .355 neck length, as the parent neck length is only .287 (I get 68thou needed).

There is about .055" difference between a 30° and a 40° shoulder angle. 287 plus 55 is 342. Looks like 15thou is plenty.

 

[STEEL SLINGER]

I think that would be a good project to under take, first step I'd take is cheap 7 RUM die and cut the bottom of till you push back the shoulder to the correct neck length your wanting and see how well it forms, if you form a major doughnut or need trimming so you
know where you need to be at with your neck diameter and hit the reamer spec first try. I always start with that anyway, I've ran into things where I find out the parent case won't respond to the forming sometimes but I think what your doing should work very well. I definitely think you'd have a good platform for launching the 195 Berger

Hi guys,

B-n-G is almost spot-on with a little experiment that I did. I purchased a set of used 7mm RUM dies from a pawn shop and asked my buddy for several of his 300 RUM cases to play with. What I ended up doing was taking the dies down to my local machine shop and had .082 milled off the bottom of the FL Sizer Die, lubed a 300 case up and sent it through. After a slight trim and if I had a chamber to fire form in, I think I would be **** close to being in business. My neck was a little longer than what I wanted, but when I fire form to the new dimensions I may loose 10 to 12 thou. and that would put me right on or just a bit over my .355 mark. Not sure as to any neck turning yet, but the case after the fact really got the gears turning in my head to possibly take this project on. Thanks for all the brain storming guys.

Mikecr; what is that program you have there for case design? Looks pretty cool!

 

[Rich Coyle]

My experience with Dave Kiff is nothing to brag about. When I ordered a custom reamer he told me I had to pay in advance so I did. When I paid I also paid for a no go gauge. I ordered my .220 Extremist which is a .220 Swift with Weatherby radii but leaving only a 1/8" neck. When the first package arrived in the mail it contained two .220 Swift Ackley reamers. I returned them along with a drawing of the correct reamer. Weeks pasts so I called. He said the reamer was in the mail. More weeks past so I called again. Finally I received another reamer. Again it was wrong. This time he made the correct reamer, but it had no neck.

Since it was about thirty miles to his shop I went there and brought the incorrect reamer. I suggest he make one according to the print. He wanted me to pay again. With the help of his secretary we found the canceled check. After more conversation he took the reamer and gave it to one of his workers. In a few hours I had a reamer that was almost right. It was good enough. I asked him about the no go gauge. He told me I used up the no go gauge money grinding the reamer so many times. What!? I used it to chamber a Savage rifle.

I also ordered a custom rifle from a guy who knew what the original drawing showed. I included the reamer with my order. When I received the rifle one of my .220 Extremist would not fit. I called him. He said when he saw the reamer he knew was not right and also knows Dave. He called Dave and asked him to make a reamer according to the original drawing. That correct reamer is what he used to chamber the new rifle.

I was doubly annoyed. While waiting for the custom I ordered loading dies according to the fired cases in the Savage. When the new rifle came I had to order new dies.

I have about a dozen wildcats. There is only one guy I will even consider doing business withnow: Dave Manson Precision Reamer. 1(810) 953-0732 voice, 1(810) 953-0735 fax.

 

[Mikecr]

There is about .055" difference between a 30° and a 40° shoulder angle. 287 plus 55 is 342. Looks like 15thou is plenty.

You don't gain neck in changing shoulder angles, you gain body length. ANY gain in neck will be out of deliberate die forming.
STEEL; the drawing is out of 'Cartridge Designer' embedded in 'RCBSdotLoad'.

 

[Edd]

You don't gain neck in changing shoulder angles, you gain body length. ANY gain in neck will be out of deliberate die forming.

Depends on how you change it. You will gain neck length and lose body length if you do it way I described. My very first wildcat project changed the angle lengthened the neck and left the body the same.

I'm not sure what you mean by deliberate die forming. I would consider all case forming projects deliberate.

 

[Mikecr]

Look at the earlier drawing showing the difference between the original and desired.
It will take 68thou neck lengthening(not 55) and 21thou shoulder lowering(not 15).
That's what it is.

Now you could try to push just the neck-shoulder junction back, but there is nothing preventing the neck from pulling back as well. Basically, collapsing the shoulder rather than lengthening neck.
And then it won't be easy to move a ~40deg shoulder back at that actual angle, again without collapsing the shoulder.

If I formed the cases for this project, I would be using a Lee Six forming die set(bushings) (which is unobtainable today). This approach would roll both the neck-shoulder junction and the shoulder at much lower angles, like ~20deg. A more gentle reshaping,, and relying on fireforming to further shape.
I would neck up/down size to form a false shoulder to headspace off for fireforming.
This is what it would look like before firing(minus the false shoulder):

 

[Deleted member 46119]

I like your design spec vs design goal. Seems "right" to me.

Forming could be done a couple ways as discussed and your experiment.

I put it in QuickDesign companion to QuickLoad. Came out same as the RCBSdotLoad CartridgeDesigner. Change the shoulder angle by pushing it down instead of blowing it out. Then loose another .015. Done.

Of course actual forming is a little harder. I like your shortened RUM die then fire form plan but someone else will need to comment if it will work properly.

You will eventually need a FL die. I got a resizer reamer with my 338/26-Nosler. Specs all the same to resize to the chamber.

Good luck.