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Necking down and changing shoulder angle?

 
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  #1  
Old 05-04-2003, 07:24 PM
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Necking down and changing shoulder angle?

Anyone have ideas/experience on this?

I'm going to change a 338 Lapua case to 30 cal and the new shoulder angle will be 40 degrees, giving it a .405" long neck.

Will a bushing type FL sizing die of Jim Cartensen's work fine for this simple change?

How many different sizes of bushings, or how far apart can one go with them and get great results?

Any help's much appreciated. [img]images/icons/smile.gif[/img]

[ 05-04-2003: Message edited by: Brent ]
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Old 05-05-2003, 08:27 PM
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Re: Necking down and changing shoulder angle?

Brent,

Your buddy Ken Markle doesn't like 40 degree shoulders. Give him a call. I agree.

Anyone have ideas/experience on this?
I'm going to change a 338 Lapua case to 30 cal and the new shoulder angle will be 40 degrees, giving it a .405" long neck.

Will a bushing type FL sizing die of Jim Cartensen's work fine for this simple change?

I've never seen Jims dies. You are going to do about what I do to my 416 case and what Ken does to his, just on a shorter scale. He moves his in a custom made arrangement in steps much like you mention, but, He supports the entire case when doing it. The short movement you propose on the neck and shoulder could give you trouble. It's actually easier to move a bunch than a little.

How many different sizes of bushings, or how far apart can one go with them and get great results?

I use a 2 piece die arrangement that I would not recommend to you for the distance you're going. FWIW, I START by moving .030 on a side. That's a ton but beleive it or not, it's the easiest move. Then I drop down to .024 on a side, then .018 and finally .015

If I had to do it over again, I would probably use a different gun! Seriously, I would probably go to .035/side on the first pass and go less on #2. The first one for you is gonna be easy because you already have the shoulder radius to begin with and that will go into the bushing very easy. After you do that though, the brass is harder and the next pass is pretty difficult. DO NOT anneal the brass for this as It will surely collapse the shoulder.

Be sure to make the last pass a small one because the concentricity of the brass will be dramatically better if you don't try to push so much on the final size. Beleive it or not, the brass will try to lean sideways when the lube is scraped off in the die on a heavy pass. It's about impossible to eliminate so just minimise it by getting one more bushing for a finish pass.
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Old 05-05-2003, 09:34 PM
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Re: Necking down and changing shoulder angle?

Thanks for the help 4mesh. [img]images/icons/smile.gif[/img] I'll keep track of your recommendations if I have to move the shoulder/body junction point lower on another case down the road. My smith in Anchorage has forming dies consisting of a short and long die with 15 different bushings he says will form any case you can imagine up to and including 416 Rigby size.

The 30/338 Lapua 40 degree Imp case here will not move anything but the neck shoulder junction back to change the angle to 40 degrees and increase the neck length at the same time. It doesn't change the body/shoulder junction length at all in this design, although it will be blown out in diameter on fire forming considerably.

How far apart on the neck bushing sizes you can go and still get the neck started in the next smaller size bushing is what I'm really concerned about. I don't want to buy anymore bushings than I really need for inbetween sizes I'll never use for anything else other than this. [img]images/icons/wink.gif[/img]

Talk to me about the 40 degree shoulder deal with you and Ken. It's a done deal now as the reamer is being ground already.

My smith recommends the 40 on anything other than something you want to feed from the mag, it just requires more work to feed is all but helps with the throat errosion as well.
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Old 05-06-2003, 08:32 AM
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Re: Necking down and changing shoulder angle?

Brent,
When using the bushings to neck down, you are forced into smaller steps due to the small radius on the bottom of the bushing. I've never measured it to know how big of a step they will take but I'm guessing .015 would about as big as you can get. The Nitrate coated bushings from Redding seem to have an even smaller radius on them as compared to the plain steel bushing from Wilson.
Normally what I do when necking down a couple of calibers is to go to a local gun show and buy a set of used dies in the intermediate caliber(s). For instance when I neck 300 H&H down to 6.5-300 I use a 7mm Rem Mag sizing die first then run the case into the FL 6.5-300 sizer die.
But in this situation with you using the 338 Lapua brass, I can't think of any dies with big enough shoulders that this case will fit in for 8mm.

I know this doesn't answer all of your questions. I've got a bunch of bushings for 30 caliber and up. I can take one of my retired 338 Yogi cases and try to neck it down and see how it works if your interested. Let me know.

Steve
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Old 05-06-2003, 12:59 PM
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Re: Necking down and changing shoulder angle?

Steve,
Thanks for the help. [img]images/icons/smile.gif[/img]

I placed a Redding .335" nitrided bushing against the bottom of the Toolhead on the Dillon 550, and with a very heavily chamfered case mouth tried to push it up into it... no dice, it just crumpled one side.

I don't have any larger bushings right now or know anyone that uses them to try out some of theirs.

Aside from maybe buying, maybe, the wrong ones, I'd have to guess at this point.

I'm dropping the neck diameter .030" so, if I could get by with maybe one .350" bushing instead of a .355" and another .345" bushing to get me down the .030" it would be nice to know.

If you'd like to give it a try for me Steve and let me know what works best, I'd very much appreciate it. [img]images/icons/smile.gif[/img]

I'm thinking I could place a washer below the bushing with an appropriate sized hole that's been tapered with a drill bit to push the shoulder back a little more uniform than I'd get than with the sharper edge of the bushing itself.

I need to bump the shoulder back at the neck junction to 2.320".

The body/ shoulder junction length is 2.177", with the diameter at the shoulder at .570".

If I could get them to chamber doing this, I'd headspace them on the bullet and fireform them, then I'll be set to FL size them using the FL bushing die when it gets here.

Doing this with the FL die itself would be much easier though.

You're right, getting another in between die large enough in diameter is the big problem.

Thanks for all the help. [img]images/icons/smile.gif[/img]

[ 05-06-2003: Message edited by: Brent ]
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Old 05-06-2003, 07:27 PM
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Re: Necking down and changing shoulder angle?

Brent,

If your bushing is nothing more than a cylinder, then I agree with Steve that the radius on the inside is going to be the limiting factor. However, if you have someone grind the ID of the bushings for you or do it with a burr gun (die grinder) you can put your own 40deg angle in there, sand it a little and it'll neck down a mile. Keep in mind that there will be a radius on the brass in front of the necked down part so you don't need to go 100% of the way to do what you want.

My dies that I go big steps with are two pieces. There are 4 tops , all the same except for the holes through the top for the neck are progressivly smaller. Just Cold rolled steel or whatever scrap I've got laying around. I think the last set was an old shaft that bearings spun on then set outside for a decade at some factory locally. It was the example piece for a replacement and I made dies out of it. The steel is then sanded in a lathe or with a die grinder and small 3m wheel. Then, wipe it with die wax and go to town. I wish I had an example of the stages of my brass to show you but I just finished all my brass 2 weeks ago so that's looking like stuff to go in the gun now. If you want a photo of the dies, let me know. I'll take one and send it to you. In another few months, I'd give you the dies for my 40deg 416/30. I just don't like the angle. After I rechamber the barrel, I'll have no use for them since I'm not going back to that again.

Oh yea, you said about the 40 degree thing. Ken says that there is a turbulance issue with a 40 shoulder that is inherantly a problem. The details are not clear to me any more but suffice to say that I will agree just because I don't like the cases forming donuts on every sizing. If the turbulance is a problem, my gun doen't shoot well enough to notice it. I have larger issues. However, I DO like my radius shouldered cases and I have some of them with 25 firings now. This lot of brass I have is much nicer than the last stuff.

The shoulder you are doing is different than mine in that your neck is so long you will most likely not have the base of the bullet in the donut of the case so it'll be no issue. That was the only problem I had with the case design. My real feeling is that if a case has enough room for the powder you want to put in, it's OK. Case configuration affects efficiency, but, the benifits of that are so small that you better really know how to make a gun shoot to realize it. My favorite analogy is, Top Fuel guys don't care about gas mileage. I'd have to shoot a lot of rounds through another case to spend the money I did for this akward case configuration. Twice. I still like it though and it cost less than a bass boat.

You know, If I was you, and wanted to try some of this stuff out, I'd look at some of these used equipment places and get a tool post grinder, a small lathe, like a hardinge collet lathe and a small mill. For under a grand I bet you could get all 3 and then doing a nice job on any small part like this would not be a $300 job at the local machine shop. With a hardinge lathe, you could easily make the form dies like I did in a CNC as long as you just stayed with the angled shoulder. Then just fire form a few cases and have dies made to match by Lee for 50 bucks and your shootin.

Something to think about.
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Old 05-06-2003, 07:43 PM
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Re: Necking down and changing shoulder angle?

Brent,

Do you have AutoCad?

I see what you're doing, your starting at the wrong end. OK, you're at .570 you said. Go down .030 on a side to .510. Then 20 on a side to .470 and so on. Now, I realise that you said the shoulder to body point isn't moving so that first step isn't really gonna do much but, I would say you have to do it anyhow to get the brass to start moving for the next step. That neck is the last piece to do. It should stay mostly straight but i've not gone down that many unsupported steps to know for sure.
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