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Help, concentricity problems.

 
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  #22  
Old 01-22-2007, 04:35 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Help, concentricity problems.

Pull it out and roll it accross the table and see if it's bent. If it's not you should be able to put it back in...hold it in place with a good piece of brass.... and retighten it. Sometimes I've had to do this 3-4 times but after some tinkering I've got it centered. Once it's centered.......it's centered for a long long time and your tinkering is done. It will be well worth the hour of tinkering. Then fine tune with my "small turn" method.
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  #23  
Old 01-22-2007, 04:56 PM
Chawlston
 
Posts: n/a
Re: Help, concentricity problems.

[ QUOTE ]
My expander ball and decaping pin are way off of center. Is it reasonable to leave the lock nut loose and just let the expander ball floar? "Sounds" reasonable to me?

[/ QUOTE ]

Roy,

Yes you can, but the problem is the case base to sexpander ball alignment. Every time you put the case in the shell holder it will be somewhat off of center. If you don't have the abiblity to turn necks, then leaving it loose may work. You would just have to try some and find out. But for the most perfect aignment of bullet to bore, turning necks is the best way to do it. Or just get some bushing dies from redding and without turning the necks that would be the best you could do. To me it is more feasable to spend the funds on a few tools rather than on a bunch of bullets, powder, cases, primers and excessive barrel wear. I mean what I have been trying to tell you guys is that you can tune a specific powder charge in 10 rounds. It only takes me 20 rounds to nail down my loads because I always use two powders..

James
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  #24  
Old 01-22-2007, 05:32 PM
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Location: medford wi usa
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Re: Help, concentricity problems.

I guess the thing that confuses me the most about bushing dies is that if you are using normal factory brass that doesn't have perfect neck thickness....and you squeeze down the outside of the neck to make it perfectly round on the outside.....haven't you just shifted the imperfection to the inside of the case mouth where the bullet is held?? I can understand how a bushing die would be great with lapua or neck turned brass but how about your normal rem and win brass that alot of hunters use?
The other thing that confuses me is the slop in a normal rifles chamber. I realize in a bench rest chamber you have tight tolerances. I don't think there is any way you can get even ammo with a <.001 runout lined up to "perfection" in a normal factory chamber.
Am I missing the boat here??
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  #25  
Old 01-22-2007, 07:19 PM
Chawlston
 
Posts: n/a
Re: Help, concentricity problems.

[ QUOTE ]
I guess the thing that confuses me the most about bushing dies is that if you are using normal factory brass that doesn't have perfect neck thickness....and you squeeze down the outside of the neck to make it perfectly round on the outside.....haven't you just shifted the imperfection to the inside of the case mouth where the bullet is held?? I can understand how a bushing die would be great with lapua or neck turned brass but how about your normal rem and win brass that alot of hunters use?
The other thing that confuses me is the slop in a normal rifles chamber. I realize in a bench rest chamber you have tight tolerances. I don't think there is any way you can get even ammo with a <.001 runout lined up to "perfection" in a normal factory chamber.
Am I missing the boat here??

[/ QUOTE ]

Yes, you are missing a major concept. Partial full-length sizing that gives you one to two thousanths compression when the round is chambered. This centers it. None of my dozen or so hunting barrels have tight chambers but they shoot like they have them. Once you fire the brass one time it takes the basic dimensions of the chamber (hence fireform). Take advantage of the close dimensions and just partial size it so that it gets the compression mentioned earlier when a round is chambered.... You will be pleased with the results.

Secondly, using bushing dies with non-turned factory brass is not perfect, but it will be closer (over the long run) than dragging the expander through the neck each reloading sequence. Hopefully this helps.

James
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  #26  
Old 01-22-2007, 08:50 PM
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Join Date: Mar 2006
Location: SC
Posts: 222
Re: Help, concentricity problems.

How well would a floating expander from redding work? Would they help solve the problem? They have them in just about every cal.
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  #27  
Old 01-22-2007, 08:50 PM
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Join Date: Sep 2001
Location: medford wi usa
Posts: 273
Re: Help, concentricity problems.

I think I actually tried the partial fl sizing by accident. After 1-2 full near max loads with my 300 wby (resizing with a lee collet die) I found the bolt had slight tension while closing. I decided to experiment with that phenominon compared to fl sizing by just bumping the shoulder back about .001-.002" inches. After hunting in crappy conditions in Alaska I decided that I would not hunt with ammo that didn't have a bit of room for dust, rain and snow. (Plus we get snow and ice here in Wisconsin.). Anyhow what I found in my rifle was that the ammo that had bolt tension to close went about 3" left of the ammo that had been sized with .001-.002 room. I actually wound up with 2 distinct groups and no discernable difference in accuracy. I'll admit I didn't do alot of testing but I was really surprised at the result. Being I don't want to hunt with PFL ammo I gave up on the concept as being one that would work for my hunting conditions. I know some people seem to like it. It just doesn't seem like a good way to prep ammo for hunting especially where dangerous game or follow up shots for the hunt of a lifetime might be involved.
After all this I think I've come to the conclusion that there are trade off's in ammo prepping. One might give a slight edge in accuracy....one will probably be more reliable in the field.
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  #28  
Old 01-22-2007, 10:24 PM
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Join Date: Jun 2006
Location: Shangri-La
Posts: 926
Re: Help, concentricity problems.

[ QUOTE ]


Once you fire the brass one time it takes the basic dimensions of the chamber (hence fireform). Take advantage of the close dimensions and just partial size it so that it gets the compression mentioned earlier when a round is chambered.... You will be pleased with the results.

James

[/ QUOTE ]

Great discussion kraky and Chawlston.

The thing I'm not sure about is the amount of compression you will get between the case-head/bolt-face and the case-shoulder/chamber-shoulder after only one firing. I took the following measurements with a Stoney Point Head and Shoulders Gauge on cases fired from a Steyr 30-06 going from new cases to the 4th firing:

new cases - 4.0400" (the measurement doesn't mean much, just it's relationship to the other measurements)
once fired - 4.0485"
twice fired - 4.0500"
3 times fired - 4.0510"
4 times fired - 4.0515"

These were neck sized with the Lee Collet and after the 4th firing the cases became hard to chamber and had to be PFLR'ed back to 4.0510" to a slight crush fit.

The point is that after the first firing the shoulder was still .003" from a crush fit. I did a test with some loads that were loaded at the same time and found that PFLR'ed loads with the shoulder moved back to a slight crush fit and crimped with the Lee Factory Crimp gave the best results.

Next is to PFLR once fired cases and see if the body sizing moves the shoulder far enough forward (which I can then push back to the proper place) to get a crush fit on once fired brass.

I'm with you Chawlston in that expander buttons are a long ago bad memory. For me it is the Lee Collet Neck Sizer and Redding Body Dies.

When is the best time to turn necks, on new cases or after the first firing?
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