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woods Offline OP
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Just ran across this on another forum and it would explain some things that are going on in my Hart chambered 280AI

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280 Ackley Improved Alert

A few years back Nosler decided to bring the 280 Ackley Improved into their list of custom brass and rifles. In order to do this they wanted to take the 280 AI to SAAMI and have it standardized.
Part of the process of standardizing the cartridge was for Nosler to see if other manufacturers had worked with it. They found that Remington had been chambering the 280 in their custom shop. Now here is where the alert comes in. Remington�s Custom Shop chose to shorten the headspace on the venerable design by .014″. When Nosler sent drawings to SAAMI they picked up that number as well.
So by a vote of the members of SAAMI the commercial established specifications for the 280 Ackley were changed from the original design. The reason reported for this change is that Remington believed it was necessary in order for factory 280 Remington ammunition to be fireformed safely in an Ackley chamber. Apparently they did not know that Ackley was the single most successful wildcatter of the 20th century. While he was not the first guy to create and �improved� design, he was the first to standardize the idea and create a safe method of fireforming factory ammo in improved chambers.
Ackley�s method was simple, he simply used a headspace gauge .004″ shorter than the factory case. This shorter headspace assured that the cartridge would be held tight between the bolt face and the junction of the neck and shoulder of the chamber during fire forming. Ackley�s method worked fine for more than 50 years before these alterations to his design were made.
Bottom line for anyone who now works with the 280 Ackley Improved you must decide which version of the chamber you will use; the SAAMI or the Ackley; you cannot safely use the Nosler brass in a traditional Ackley chamber, although it would still be safe to fire form factory ammo in a SAAMI/Nosler chamber




With Nosler 280AI new cases I have measured .017" headspace with the Hornady headspace gauge and that would explain my primer flattening

[Linked Image]
[Linked Image]

on new cases which were with a known load, no pressure signs and have since been reloaded and holding primers fine

[Linked Image]

If they did this, WHY! For the last 40 years 280AI's have been chambered and now they changed it because Remington had a wild hair! mad

And the bigger question is Why was there no warning or cautions on the box of Nosler 280AI brass! mad


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Good to know, as I have become somewhat lazy and was thinking about trying Nosler's .280 AI brass. Most of my current stock (R-P) has been reloaded five or six times and I prefer to use brass with three or fewer trips through the dies for hunting.


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I saw that also, so went out and measured a bunch of fired Nosler brass. I then necked up an unfired nosler case to 30 caliber and created a false shoulder that would barely allow me to chamber the round, loaded and and fired it. Measured exactly the same as the previous fired cases. I then turned a neck on a piece of remington brass and loaded it up and fired it, same measurement. (BTW I am not talking about case length, I am using a stub reamed with my reamer that indexes on the shoulder) I then took an unfired case and put a piece of tape on the case head, bolt would close but very tight. I think I was compressing the case a little.

Based on that I was expecting to find a saami reamer and go gauge. So I ran out to the other shop and checked my reamer and go gauge, I am using a standard AI reamer and a .004 under 280 go gauge. I am unsure whether new nosler brass is using the specs referenced in that article.

I would not let it bother me, or stop me from using nosler brass but I am pretty prone to not oversizing my brass.

Edited to add that the unfired Nosler cases measured easily within .001 of my fired cases.


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I think Remington must get their engineers from some 3rd world country, not to mention they also have window-lickers in the marketing dept. The SAUM fisaco immeadiately comes to mind.

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This wasn't done because Remington had a wild hair. It was done because the guys at Remington found that they needed more than -.004 to have sufficient crush on factory cartridges. The reason for this might have been some variation in shoulder angle on a particular lot of factory ammo (Remember, all ammunition is made to be within certain tolerances. The distance to the juncture of neck and shoulder is not necessarily precise. It is the measurment to the datum line which is precise).
Ackley made mistakes too. Careful study of his drawings and dimensions will reveal this. GD

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I reread the original article and realized that these changes occured a few years ago. Since the changes were originally to the .280 remington and just carried over to the 280AI my measurements would have no bearing on this discussion as my .280 -.004 go gauge is pretty recent vintage, and my reamer while older than my gauge probably should meet the specs also.

I do not have a .280AI that would be effected, so there may be a problem, I cannot say. I would guess that if someone could figure when the changes tot he .280 remington were made an idea of the vintage of affected rifles could be determined.

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Originally Posted by greydog
This wasn't done because Remington had a wild hair. It was done because the guys at Remington found that they needed more than -.004 to have sufficient crush on factory cartridges. The reason for this might have been some variation in shoulder angle on a particular lot of factory ammo (Remember, all ammunition is made to be within certain tolerances. The distance to the juncture of neck and shoulder is not necessarily precise. It is the measurment to the datum line which is precise).
Ackley made mistakes too. Careful study of his drawings and dimensions will reveal this. GD


I found this while Googling this topic and may explain Remington's reason for altering the original Ackley:
"Although Norma brass cases are more expensive than domestic cases, the outstanding dimensional consistency of the Norma 280 cases are in my opinion worth the extra cost. I have found that Remington cases are as much as 0.007 undersize and some with more than maximum headspace. Since all cases have to be fire formed the headspace is easily eliminated. But the bulge on the bottom can not, and will eventual allow for primer pocket expansion. These cases were made for semi auto rifles and intended to fall into the chamber."


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I have loaded for three different 280AIs that were all made before Nosler starting making their brass. All my 280AIs were formed from Rem brass. When the Nosler brass became available, I switched to it in all three rifles. Never had a problem. I read the above on the Nosler site and then measured the headspace of unfired Nosler brass with fired neck sized brass. There was 0.009 difference. I have seen much more with belted mags. Never had a problem with the Nosler brass and will continue to use it. I hange the dimentions more when using Rem brass to form the AIs.Rick.

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Good to know.


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I reread the original article this morning. I may have had some pain killer induced lack of reading comprehension. I thought from reading paragraph two that the .280 remington deminsions had been changed, but paragraph two is sorta ambigous.

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Been using Nosler custom brass on my Jarrett since forever....not a peep of trouble.


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I had my only .280 AI set up for Nosler brass, and had no trouble fireforming Remington .280 cases.


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Originally Posted by Godogs57
Been using Nosler custom brass on my Jarrett since forever....not a peep of trouble.


I am with you on that, I have used the nosler brass in at least a half dozen of them without a problem. I just do not know whether the headspace on the nosler brass is as short as stated in the article. Using my homemade comparator the brass is basically the same size as a chamber reamed with a -.004 gauge and older 280AI reamer. I been scratching my head over it but not enough to actually go look at my reamer and go gauge dimensions again.

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Here is what Dave Manson of Manson Reamers has 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
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Pretty much sums it up


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Caz Offline
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OK, so if I am reading this correctly....I am finishing a custom build chambered for the original .280 A.I.. I had been planning on using the Nosler 140 gr. ammunition, but now am thinking this is not a good idea? I am confused on whether the answer is Yes, No or Maybe...

New to customs, so any help would be greatly appreciated...

I have put waaaay to much into this rifle to risk catastrophic failure.....

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Originally Posted by woods
Here is what Dave Manson of Manson Reamers has 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



Pretty much sums it up


That write up by Manson is impressive however it raises doubts as well. No wonder nobody has made an AI commercial until trying now.

Suppose I could neck size a 'factory' 280AI with the 7mm WSM or 7mm RM FL die to start.

The jury is further out on a 280AI now. I still want to handle a 84L. Somehow a new 7mm WSM barrel for one of the rifles here seems like more of a sure thing.

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It may or may not be a good idea to use the Nosler brass. You will not know unless you measure the Nosler brass against a fired case from your chamber. Or you could use tape to "headspace" the nosler ammo to your chamber to see if it will be a problem.
What I finally figured out is that Nosler is not selling fully formed brass. The shoulder is not at a full 40 degrees so that it will hold the cases against the boltface even in a non saami chamber. Whether this was done on purpose by nosler I dunno.
If your going to headspace the case to your chamber strip your bolt and make sure that it closes with no resistance. Put a piece of tape on the case head of a Nolser case. If you feel resistance closing the bolt all will be fine. If I had to put two pieces of tape on the case head to feel resistance I would probably be okay with it. I would not not feel okay with 3 pieces.

I am not saying that you should leave the tape on the case when firing, it is just for measurement. I took a bunch of pics of measurements of nosler brass measured with a comparator a couple weeks ago but never posted them. Will see if I can find them so you will see what I am talking about.

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Forgot to add that when I called PTG last week the sales girl knew nothing of the change when I inquired as to whether I needed a Saami reamer. I had spoken with Dave but had let him get away before I remembered to ask that question.

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Originally Posted by woods
and now they changed it because Remington had a wild hair!


Someone has to be the industry leader, and that is Remington.



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Originally Posted by Caz
OK, so if I am reading this correctly....I am finishing a custom build chambered for the original .280 A.I.. I had been planning on using the Nosler 140 gr. ammunition, but now am thinking this is not a good idea? I am confused on whether the answer is Yes, No or Maybe...

New to customs, so any help would be greatly appreciated...

I have put waaaay to much into this rifle to risk catastrophic failure.....


It may or may not be a good idea. If you are a reloader it would be better to get 280 rem caliber brass and fire form it rather than getting 280 Ackley brass. With the 280 rem brass there is never a problem, no matter if you have a SAAMI chamber or an old standard chamber. Once you fire form the 280 rem brass you will be able to use a headspace gauge (like the Hornady or Sinclair not the go-no-go kind) and determine which chamber you have and measure the headspace you will have on the Nosler ammunition beforehand to see if there will be a problem.

If you are not a reloader then ask the gunsmith or company that reamed your chamber or have a chamber cast made.


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