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.280 AI controversy explained ...

 
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Old 08-04-2013, 08:48 AM
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.280 AI controversy explained ...

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Old 08-04-2013, 10:26 AM
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Re: .280 AI controversy explained ...

Bullchips!!
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Old 08-04-2013, 10:49 AM
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Re: .280 AI controversy explained ...

Quote:
Originally Posted by woods View Post
Bullchips!!
Please elaborate, comment as such is no help to anyone! If you have something constructive or helpful information, please by all means share.
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Old 08-04-2013, 11:21 AM
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Re: .280 AI controversy explained ...

280 Ackley Improved Alert | GunsmithTalk

January 13, 2010 · 10:28 pm

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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.

Compare the length of these two designs.

UPDATE: See this post for new information




Now I have a 280AI that was rebarreled by Hart before the SAAMI dimensions were made official. Before all this information became available I purchased a box of Nosler 280AI brass. I had severely flattened primers (fire forming less than max load)



Measuring with the Hornady comparator to the shoulder datum the measurements on the Nosler 280AI brass going from new brass to once fired was:

new case - 2.1350" (subtracting of the comparator and holder when zeroed at 2")
once fired - 2.1500" (neck size with Lee Collet)
twice fired - 2.1520" (neck size with Lee Collet, very slight crush fit, fully expanded)

So the Nosler 280AI brass expanded .017" at the shoulder

When I fire form Nosler 280 Remington caliber brass I do not get flattened primers. Obviously I can not take measurements on the datum line with the Hornady comparator on a 280 Remington case, so the final results are all the data I have.

Now this is in MY rifle chambered by a reputable company Hart



and it has the very remote possibility of being the only one in the world if you so choose to believe that has this chamber

But to have someone take 2 reamers, origins unknown, and say that there is NO controversy of anything to be concerned about is LUDICROUS

IMO YMMV
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Old 08-04-2013, 12:30 PM
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Re: .280 AI controversy explained ...

280 Ackley Improved vs. 280 Rem. Improved 40 Degree | Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment

280 Ackley Improved vs. 280 Rem. Improved 40 Degree
The SAAMI spec cartridge carries the approved name of " 280 Ackley Improved " .
The older wildcat has several names including 280 Ackley Improved 40°, 280 Rem Improved 40°, 280 Imp 40°, 280 Ackley, 280 Rem Imp, and more.
The SAAMI spec 280 Ackley Improved chamber is .014 inches shorter at the datum line headspace dimension than the traditionally accepted wildcat chamber spec as previously produced.
Our current production dies are for chambers that are cut to the SAAMI specification and are stamped "280 Ackley Imp".
Any Redding dies made before 2011 are stamped " 280 Rem Imp 40° " and are built to the originally accepted wildcat specs.
These older dies will not bump the shoulder of cases for a SAAMI chamber. In other words, the old dies are too deep for the current SAAMI chamber.
Redding makes a Competition shellholder that is .014 deeper than the standard #1 shellholder so the owner of a wildcat chamber can use the current SAAMI spec dies for safe resizing.

Failing to use this shellholder or to back the die away from a standard shellholder by a minimum of 0.014" will result in too much shoulder bump which may create an unsafe, excessive headspace condition when fired in a traditionally dimensioned wildcat chamber.

To find the die part numbers for a current production SAAMI spec. rifle, please download our current catalog as a .pdf from Home | Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment.
You will find these dies listed in Series C and Category II. Limited quantities of the traditional wildcat dies which are marked " 280 Rem Imp 40° " are available at Custom Series Die prices.

Bottom line, don't rely on only the web.
The names many list for this cartridge can be misleading.
Remember, they are wildcat cartridges and adhere to no formal standard.

Note: Any dies that Redding makes for SAAMI approved cartridges are always stamped with the SAAMI approved name or abbreviation.



I amend my previous first post

HORSEHOCKEY!
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Old 08-04-2013, 12:40 PM
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Re: .280 AI controversy explained ...

New and Improved: The .280 Ackley Improved - RifleShooter

For reasons too lengthy to go into here, the headspace dimension for the .280 Ackley Improved cartridge approved by SAAMI and introduced by Nosler turned out to be shorter than headspace gauge manufacturers had established for the original Ackley version. Some reloading die makers have responded by offering different die sets for the two.

Dies made by Redding for the Ackley version prior to 2011 were marked “280 Rem Imp 40 Degrees.” They are still available. Dies for the Nosler version are marked “280 Ackley Imp,” which is the SAAMI-approved abbreviation. In the past, RCBS dies for the Ackley cartridge were marked “280 Imp 40 Degrees,” and they will continue to be so while dies for the SAAMI/Nosler version will be marked “280 Ackley Imp.”

The important difference between the two die sets is in their full-length resizers. Since headspace dimension of the SAAMI cartridge is shorter, the shoulder in a die reamed for the Ackley cartridge won’t make contact with the shoulder of the case.

If a die reamed for the SAAMI version is screwed into the press far enough to make contact with the shellholder and used to resize a case fired in a rifle chambered for Ackley’s version, the shoulder will be set back for an increase in headspace. But it can be used by screwing the die in just far enough to lightly bump back the shoulder enough for trouble-free chambering of the cartridge. So when purchasing reloading dies for a rifle it is important to know which version of the .280 AI it is chambered for.

If other companies introduce rifles in .280 Ackley Improved, they will likely be chambered for the SAAMI version, and Nosler cases and ammunition will surely work fine in them. But since the original .280 Ackley Improved is a wildcat, gunsmiths who have chambered rifles for it over the past 65 years or so have not always agreed on precisely how deeply the chamber should be reamed.

So to be on the safe side, it is not a bad idea to have the headspace of a rifle chambered for Ackley’s version checked by a gunsmith to determine its suitability with Nosler cases and ammunition. Kenny Jarrett, who has chambered more than 1,000 rifles for the original Ackley version, agrees with my opinion. So does Dave Kiff of Pacific Tool & Gauge, which makes chamber reamers and headspace gauges for both versions.



Personally I don't use go-no go-field gauges as used by gunsmiths and IMO they have little use for us as reloaders. To say that no problem was created or does not exist is again

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Old 08-04-2013, 01:41 PM
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Re: .280 AI controversy explained ...

Good, that's much better ... now let the end-users heed and learn from all the information available.
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