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Question on body taper.

 
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  #1  
Old 12-15-2009, 10:25 AM
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Question on body taper.

I am new to the whole wildcatting thing and am spending hours reading through old posts on this site.

I wish to thank all the members for the time they put into this site and their pursuit of long range nirvana.

Hopefully this question is not too ignorant.

Is there a reason that one would avoid straightening the body taper on the 30-06? Say for instance when going to the 280AI, I would guess that you would gain some additional powder capacity by also straightening out the case wall.

Is it due to case extraction?

Ad if that is the case, would a sako style extractor be able to manage the process?

Edit,

I guess it also depends on if the case already has more than enough capacity.....I am as stated before, just getting started so my questions may be totally ignorant. I am not knowledgeable as to case capacity of the 280AI, but looking at how they beefed up the 284shehane started me thinking in this direction. Just trying to get the most out of my 30-06 action.
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Last edited by Aldon; 12-15-2009 at 10:33 AM.
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  #2  
Old 12-16-2009, 09:22 AM
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Re: Question on body taper.

Here you go:
.280 Ackley Improved
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  #3  
Old 12-16-2009, 09:58 AM
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Re: Question on body taper.

Thanks for the link Rock.

I was aware that the Shoulder angle on the AI was increased to ~ 40 degrees.

At one point the article does mention straightening the case but it appears it still has the taper that the 30-06 does. It straightens the case at the top where the sharper angle increases the length a bit. Thereby increasing capacity.

In order to clarify the question that I am trying to get answered, why would one not use a straight walled design as opposed to the slightly tapered one on the 30-06 to get a couple of more grains capacity.

On 6mmbr site in the section on 7mm's it discusses the changes Shehane did to get the additional performance out of the 284. It says he essentially straightened the case taper an additional .010 which seems to be something one could do in addition to changing the shoulder angle when going to the Ackley AI.

Or is this .010 straightening already part of the change when modifying to the Ackley AI?
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“When a long train of abuses and usurpations, pursuing invariably the same object evinces a design to reduce them under absolute despotism, it is their right, it is their duty to throw off such governments. …” Jefferson

We are very close to this point now.
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  #4  
Old 12-16-2009, 10:10 AM
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Re: Question on body taper.

OK, When I compare the case drawings of between the 280 and the 280 AI on Ammoguide it does look like the case taper has been increased on the AI.

It just does not mention how much.

I guess that answeres my question.

Thanks for the assist Rock.

Aldon
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“When a long train of abuses and usurpations, pursuing invariably the same object evinces a design to reduce them under absolute despotism, it is their right, it is their duty to throw off such governments. …” Jefferson

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  #5  
Old 12-16-2009, 01:20 PM
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Re: Question on body taper.

Aldon,

Here is a link to a great site that shows case drawings and dimensions...

page8d

You will see that the OD of the base of the 280 Rem is .470 and the OD at the shoulder is .441. In the AI version the the wall is straightened to a .445 OD whicl leaves .025 of taper.

I'm not a smith or chamber engineer, but I would think that a straight wall chamber in rifle cartridges would lead to stuck cases, especially with warm loads.

Hope that helps,

Mark
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  #6  
Old 12-16-2009, 02:31 PM
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Re: Question on body taper.

Thanks Mark.

That is what I was looking for.

Thanks for the link.

If I read throught the site over the next coupel of months I might get to where I have some limited knowledge

That dimension may have been on the ammoguide drawing as well but my machinest skills are rusty to say the least.

Aldon
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“When a long train of abuses and usurpations, pursuing invariably the same object evinces a design to reduce them under absolute despotism, it is their right, it is their duty to throw off such governments. …” Jefferson

We are very close to this point now.
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  #7  
Old 12-16-2009, 03:03 PM
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Re: Question on body taper.

Aldon,
You are going to need some taper in your case design, or you won't be able to eject the case after firing. I don't know at what point that happens, but I won't go much under . 020 taper, depending on the length of the case.
Maybe a smith could chime in here.
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