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280AI question

 
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  #22  
Old 03-20-2011, 09:54 AM
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Re: 280AI question

Upon a second reread without the nightly pain meds the article is ambiguous in the second paragraph as to which was changed by remington the 280 or the 280AI. I am guessing they are referring to the 280 AI even though the author states 280 with no other identifiers other than "venerable design." I took that statement literally to mean .280 remington.
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  #23  
Old 03-20-2011, 01:15 PM
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Re: 280AI question

Quote:
Originally Posted by eddybo View Post
Upon just rereading the link, I see why my chambers are to the newer specs. The .280 remington specs were changed, and the changes followed over into the .280 AI specs. Thus a .280 remington go gauge -.004 will match the new headspace specs. I am using a newer go gauge where I am very sure that these specs would be reflected. (Actually my reamer probably does also since it is only about 4 years old) So my measurements may have no bearing since I was measuring new design brass against a new design chamber.

Anybody know the year when the changes to the .280 remington were made?

What about the year that the 280AI was granted saami specs?
Hey eddy

According to this SAAMI page

http://www.saami.org/PubResources/CC...0-%20Rifle.pdf

the 280 remington drawing date was 6/20/86 and the 280 Ackley Improved was 4/10/08

So I don't think that changes in the 280 rem specs has anything to do with this. Now on another forum someone mentioned that the reason was because of variances in the Remington factory load 280 remington caliber brass was as much as .007" in the dimension from case head to neck/shoulder. If this is the case then 50 years went down the tube because of Remington poor quality control.

Why doesn't that surprise me?
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  #24  
Old 03-20-2011, 02:48 PM
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Re: 280AI question

I called and spoke with a guy who knows some stuff. He said not all 280AI reamers are created equal. but it is the go gauge that matters. He indicated that so long as the headspace was working not to worry with it.

Quote:
Originally Posted by woods View Post
Hey eddy

According to this SAAMI page

http://www.saami.org/PubResources/CC...0-%20Rifle.pdf

the 280 remington drawing date was 6/20/86 and the 280 Ackley Improved was 4/10/08

So I don't think that changes in the 280 rem specs has anything to do with this. Now on another forum someone mentioned that the reason was because of variances in the Remington factory load 280 remington caliber brass was as much as .007" in the dimension from case head to neck/shoulder. If this is the case then 50 years went down the tube because of Remington poor quality control.

Why doesn't that surprise me?
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  #25  
Old 03-21-2011, 05:20 PM
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Re: 280AI question

Here is what Dave Manson of Manson Reamers had to say:

QUOTE

From the reamer/headspace gage maker's point of view, SAAMI standardization of the 280 Ackley Improved has created problems. Mostly, it's a matter of making sure folks are informed about the change, proper fireforming--if they want to go this route--and which ammo to use in which chamber.

Ackley's intent, with rimless, shouldered cases, was to headspace the improved chamber so that the un-improved parent cartridge could be loaded and safely fired in it--the parent round was held between the breechface and the neck/ shoulder junction of the improved chamber. He advised that the breech-face-to-neck/shoulder junction in improved chambers be held some.004" to .006" shorter than in the parent chamber. Traditionally we, and other reamer makers, have done this, grinding reamers with a MINIMAL RADIUS at the N/S junction for more positive headspacing during fireforming.

Nosler/SAAMI shortened the traditional 280 AI headspace another .014". Additionally, the radius at the N/S junction was specified at .060" +.025". This was likely done because it's very difficult to form 40-degree shoulders with small radii--they're supplying fully formed ammunition, remember.

What does this mean for the owner of a 280 AI?

First, if you have one headspaced the traditional way, don't buy Nosler ammo unless you want to see evidence of excess headspace and risk case separation--its shoulder location guarantees at least .014" excessive headspace. When you need new cases, fireform them from 280 Remington brass.

Second, if you have a SAAMI-spec chamber, you can buy Nosler ammo OR fireform 280 Remington. The N/S junction on the SAAMI chamber IS .014" closer to the breech face, but the .060" radius at this points provides a little more room to accomodate 280 Rem ammo. You may feel a little resistance as you turn down the bolt handle, but it will go and the case will be held securely during fireforming.

Finally, re-loading. Don't use dies made to the old spec to re-size cases fired in SAAMI-spec chambers. The few re-size dies I checked that were made to the "old" spec would not reach the shoulder of a case fired in the SAAMI chamber.

You CAN use SAAMI-spec dies to re-size cases fired in old-spec chambers, but be sure to set the die so it barely touches the shoulder of the fired case. DO NOT set the die so it bumps the shellholder when the ram is up--you'll introduce excess headspace or crush the case.

There are different versions of the 280 AI out there, so this commentary doesn't apply to everyone. If anyone has questions about his specific rifle, I'm willing to try to answer them.

Dave Manson
1-810-953-0732

UNQUOTE


Now that I know I can deal with it but I do think it is irresponsible for Nosler to sell their 280AI cases or boxed loads without a heads up.
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  #26  
Old 03-22-2011, 01:07 PM
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Re: 280AI question

When you can barely chamber a piece of new brass with a single layer of tape on the case head headspace is not an issue. I would guess that maybe there are chambers out there with excess headspace on Nosler brass, but maybe not. We all know what the article states, but they do not show any real measurements taken from actual Nosler brass. Looks to me as if Nosler brass is not fully formed to a 40 degree shoulder. I am wondering if maybe Nosler did this as a way of CYA.

I think it would be wise for people to use a comparator to measure their fired brass against nonfired Nosler brass before shooting Nosler 280AI brass. I do not think that as many as most would imagine will have headspace problems as the article wil lead one to think.
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