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280AI trim length

 
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  #1  
Old 05-02-2011, 10:06 PM
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Location: Canon City, Colorado
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280AI trim length

I've been gathering a wealth of info off of this site for over a year now and have come across a question that i've been unable to find the answer to. Can somebody explain why the trim lenth for a 280 AI is 2.525 yet it is apparently safe to fireform 280 Rem with a trim length of 2.540? Do i trim after fireforming or is it o.k to trim before??? Or, why trim to AI specs at all if .015 more doesn't really matter in this case? I'm loading new Rem brass. Thanks for any help you can give and also for all of the great info so far. Great site!
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  #2  
Old 05-02-2011, 10:33 PM
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Re: 280AI trim length

Quote:
Originally Posted by mm242 View Post
I've been gathering a wealth of info off of this site for over a year now and have come across a question that i've been unable to find the answer to. Can somebody explain why the trim lenth for a 280 AI is 2.525 yet it is apparently safe to fireform 280 Rem with a trim length of 2.540? Do i trim after fireforming or is it o.k to trim before??? Or, why trim to AI specs at all if .015 more doesn't really matter in this case? I'm loading new Rem brass. Thanks for any help you can give and also for all of the great info so far. Great site!

You need to know what your chamber length is .

SAAMI spec is 2.525 for the AI and 2.540 for the 280 rem.

Nosler is the only one loading the 280 AI and recently standardized it by submitting it to
SAAMI (It had not been one of the SAAMI cartriges before).

It almost looks like they wanted to corner the ammo market for the AI version because they
changed the dimensions slightly over the standard AI reamers of the past. they were designed
to fire form using the standard 280 Rem cases.

Older AI reamers are made long enough to fire form 280 ammo in them. This is the reason
you need to find out what is the case length in your chamber.

If a fired 280 case will fit in your chamber with out effort it is probably OK, if not you chamber
is to short to use without trimming.

Ultimately what you want is a case neck that is .010 to .020 shorter than your chamber.

J E CUSTOM
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Last edited by J E Custom; 05-03-2011 at 09:57 PM.
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  #3  
Old 05-03-2011, 01:26 AM
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Re: 280AI trim length

Here is one of the old traditional case drawing and the new SAAMI case drawings



You'll notice they both say 2.540"

I know, my Nosler #5 manual says 2.525" also

I suspect that since the case length normally decreases when fireforming a 280 Rem case, that there was some acceptance of a shorter overall case length as normal and they just listed it that way.

Who knows but in case you weren't aware of this problem:

280 Ackley Improved Alert | GunsmithTalk

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

So since I have an older 280AI chamber I plan on just using 280 Rem brass for reloading and not buyin any Nosler 280AI cases.
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  #4  
Old 05-03-2011, 08:34 AM
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Re: 280AI trim length

Now I'm confused.....I read on Nosler's site, I believe it was your article actually, so being concerned I called Nosler's tech support. There I was referred to and spoke with a gentlemen, (Sorry forgot his name) and he pulled up the forum and looked at the article. From what he told me, again this is their tech staff, Nosler had no intention of changing the dimensions of their brass, either loaded or prepped cases. Have you or anyone else measured any of their "new" brass to see if in fact they did or not. I hope this isn't a case of the right foot not knowing what the left one is doing.

I only ask as I've been using their brass without any issues the way it was or used to be. If any changes are now made I'd like to be sure about it.....Thanks.
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  #5  
Old 05-03-2011, 10:31 AM
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Join Date: Dec 2009
Location: Canon City, Colorado
Posts: 11
Re: 280AI trim length

Thanks, guys... when the question came up from the smith as to how i wanted the chamber finished i told him to set it up for the standard 280 Rem brass, which by the way chambers pefectly.... slight crush fit( I was pretty much confused over the whole SAAMI-Nosler ordeal so tried to keep it as simple as possible) I wasn't aware or maybe just forgot that the brass actually shortens when fireformed. Woods, you were correct- got the spec from my Nosler manual. A phone call to the smith verified that the chamber length is set for regular 280 brass and to keep an eye on the case lengths. Thanks again for your responses.
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  #6  
Old 05-03-2011, 10:34 AM
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Join Date: Jul 2004
Location: Texas
Posts: 5,373
Re: 280AI trim length

Quote:
Originally Posted by woods View Post
Here is one of the old traditional case drawing and the new SAAMI case drawings



You'll notice they both say 2.540"

I know, my Nosler #5 manual says 2.525" also

I suspect that since the case length normally decreases when fireforming a 280 Rem case, that there was some acceptance of a shorter overall case length as normal and they just listed it that way.

Who knows but in case you weren't aware of this problem:

280 Ackley Improved Alert | GunsmithTalk

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

So since I have an older 280AI chamber I plan on just using 280 Rem brass for reloading and not buyin any Nosler 280AI cases.
A very good explanation Woods !!!!

Any thing that Dave Manson comments on is worth listening to and may save s shooter lots
of problems.

I still dont understand why Nosler would change the tried and true dimensions that allow
you to shoot standard 280 REM and fire form at the same time. It looks like they have shot
themselves in the foot for selling ammo because any re loader that is interested in the AI version
would rather not be locked in to one brand of ammo/brass when they can chose from 8 to 10
brands and fire form while hunting. (When properly chambered and head spaced the 280 ammo
can be extremely accurate when fired in a Traditional AI chamber).

I am currently building a pair of 280 AIs, one is an F class and the other is a lighter hunting
rifle. They will have the same chambers and head space so the hunting rifle and match rifle
can be used with with standard 280 ammo and fire form at the same time, then load the AI
to a higher velocity for the match rifle or larger bullets at the same velocity for hunting.

Also if you want to buy premium brass Norma makes it in 280 and 270.

Loaded ammo for the Nosler 280 AI version is the only one available at this time, so why
would any one to limit themselves to one manufacture when there are lots of brands of ammo
and brass for the "Standard" 280 Rem.

As we all know some times we may have a ammo problem (Especially these days) and wouldn't
it be nice to be able to buy any ammo and save a hunt ?

J E CUSTOM
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Last edited by J E Custom; 05-03-2011 at 09:56 PM.
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  #7  
Old 05-03-2011, 04:53 PM
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Join Date: Jun 2006
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Posts: 923
Re: 280AI trim length

Hey J E

I think you're getting Hornady and Nosler confused. Nosler is the only manufacturer that offers 280AI brass and ammunition. Nosler is the one who coordinated with Remington custom shop to spec the drawings.

Here is what the additional headspace from Nosler 280AI brass will do if fired in an older dimensioned chamber



Now flattened primers is not the end of the world if it is due to a little extra headspace and not pressure, so I decided to go ahead and fire and use these. Perhaps they will have more thinning at the pressure ring but I will keep an eye on that.

mm242 you will probably not have any issues with a newer 280AI firing the 280AI brass or 280 Rem brass, the problem should only surface in older chambers with the 280AI brass.

muleyman when the Nosler tech said Nosler didn't have any intention on changing the brass it could be because the drawing with the headspace change happened in 2008

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

and the drawings were probably submitted for a period of time before that. They were probably producing the 280AI brass at the new dimensions for 5 years at least and maybe all of their brass has been at the new dimensions. So he was essentially saying "Nosler is right and we ain't changing nuthin!" kinda thing. Typical.

What puzzle me a little is that with the reduced headspace of ~.014", the 280 Rem brass should have a bigger crush fit than was typical in the older 280AI. Used to be there was only an allowance of ~.003" crush fit on the 280 Rem brass but in the new SAAMI chambers it should now be .017". Guess even that much is not much of a problem for a bolt action.

IMO Remington figured out that they had poor quality control on the dimensions of their 280 Remington Remington brass and they were not getting the crush fit deemed necessary for forming to a 280AI. So rather than straighten up their act and put out more consistant brass, the Remington custom shop decided to add the headspace to absolutely confirm the crush fit on their proprietary brass. Then when Nosler asked them, Remington gave Nosler the dimensions of their 280AI custom shop chambers. 50 years of tradition down the drain.
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Last edited by woods; 05-03-2011 at 04:58 PM.
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