280 Ackley Chamber

[Bill in AZ]

I bought a 280 Rem Improved 40 degree reamer and then a couple years ago bought 200 pieces of new Nosler 280 Ackley Improved brass in the 50 piece boxes. Also have a set of Redding dies marked 280 Remington Imp 40 degree. I still have not built the rifle over concerns that the chamber will not match up with ammo made with my dies and if either will work with my expensive (virgin) brass. I have been a handloader for 35 years and this is a mess. If I did not have some $400tied up in reamer. dies, and brass I would abandon this mess and go with 284 Winchester (but brass for this is another obstacle).

This 280 Improved with what appears to be two standards (but then one story is they are the same?) has me over a barrel.

I have about 10 PT&G reamers and have had stellar results with them, Shipping has been 1 week to 4 weeks as stated at time of order.

 

[DirectDrive]

I bought a 280 Rem Improved 40 degree reamer and then a couple years ago bought 200 pieces of new Nosler 280 Ackley Improved brass in the 50 piece boxes. Also have a set of Redding dies marked 280 Remington Imp 40 degree. I still have not built the rifle over concerns that the chamber will not match up with ammo made with my dies and if either will work with my expensive (virgin) brass. I have been a handloader for 35 years and this is a mess. If I did not have some $400tied up in reamer. dies, and brass I would abandon this mess and go with 284 Winchester (but brass for this is another obstacle).

This 280 Improved with what appears to be two standards (but then one story is they are the same?) has me over a barrel.

I have about 10 PT&G reamers and have had stellar results with them, Shipping has been 1 week to 4 weeks as stated at time of order.

So you have 280 Ackley SAAMI spec brass and the "Traditional" die set.
Redding dies marked 40° are the Traditional die set - Redding clarifies this on their site.

If you're a handloader, why not use the Traditional 280 Ackley chamber ?
Seat your first batch of cartridges so the bullet is into the lands.
Then for batch #2 you're all in for normal 280 Ackley Traditional loading.

Someone might come along and say "No worries, the chambers are essentially the same."
And that's OK, because no matter what, you now have brass that now conforms to your chamber.

From Redding :
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 www.redding-reloading.com.
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. See Rifle & Handgun Die Charts

 

[Pdvdh]

I have about 10 PT&G reamers and have had stellar results with them, Shipping has been 1 week to 4 weeks as stated at time of order.

Glad you've had a successful track record with those reamers.

Chad Dixon with LongRifles, Inc used to almost solely use PT&G reamers for all his chambering work. He cuts a LOT of chambers in his shop. He eventually got Kiffed, no longer purchases reamers from PT&G. If you wanna research the Sniper's Hide forum, you'll be able to find his own comments in his posts. They aren't near as tempered as mine are here.

I purchased one PT&G chamber reamer for a wildcatted 338 cartridge from PT&G. It only cut on two of the cutting edges brand new. My gunsmith was barely able to cut a chamber with it, even though he had a pressurized cutting oil system running during the chamber cutting process. He wanted to send it off to Dave Manson for resharpening before using it, even though it was brand new, after he realized it was a PT&G reamer! Shoulda let him cuz it turns out he was right about that.

I promptly sent that reamer off to Dave Manson to get it sharpened before any consideration of using it a second time. After Manson sharpened it, the next gunsmith that used the reamer report no issues whatsoever cutting my chamber.

So we takes our chances, and we lives with the consquences.

 

[Swamphunter]

I have one traditional and one saami. I can't fire the original ammo in the saami gun, bolt won't close. Never tried it the other way around. People told me they are the same but they aren't. Else I could interchange them. With all the confusion I just bought a resizing die for the saami and am careful to keep the brass separate. They should have kept the specs the same as the original and there wouldn't be this conundrum.

 

[25WSM]

I'm not getting into arguments about this anymore. But if you use the exact same headspace guage for both then how can it be any different? Swamphinter have you measured the shoulder length of each cartridge from your 2 rifles. If one chamber was cut minimum and the other max they are still within spec but no way the one fired in the max chamber will fit in the minimum one. A 280ai is a 280ai. The original and the Sammi are the same. 280improved or 280rem imp can mean anything. But a true Ackley chamber and the Sammi chamber are the same. I do all my 280ai Chambers the same as Ackley did and the nosler brass fits perfect. If you want to believe that they are different go ahead it won't hurt my feelings any. The .014 difference is only there because they are measured at 2 different spots on the neck. Ackley measured different than Sammi so it was changed to Sammi spec so it could be legit. Same cartridge. Same headspace guage. Same brass. Must be a duck.
Shep

 

[Pdvdh]

I'm not getting into arguments about this anymore. But if you use the exact same headspace guage for both then how can it be any different? Swamphinter have you measured the shoulder length of each cartridge from your 2 rifles. If one chamber was cut minimum and the other max they are still within spec but no way the one fired in the max chamber will fit in the minimum one. A 280ai is a 280ai. The original and the Sammi are the same. 280improved or 280rem imp can mean anything. But a true Ackley chamber and the Sammi chamber are the same. I do all my 280ai Chambers the same as Ackley did and the nosler brass fits perfect. If you want to believe that they are different go ahead it won't hurt my feelings any. The .014 difference is only there because they are measured at 2 different spots on the neck. Ackley measured different than Sammi so it was changed to Sammi spec so it could be legit. Same cartridge. Same headspace guage. Same brass. Must be a duck.
Shep

So Redding has been wrong for the past 10 years? And continues to present false information to their customers? You should contact them and ask them to correct their website. You could also let them know they're wasting their time and resources manufacturing a shell holder that's had 0.014" shaved off the top, so that owners of their original "traditional' 280 A.I. resizing dies can use those dies to properly resize cases for the SAAMI standardized "280 Ackley Improved".

Have you cut more 280 Ackley chambers than the number of resizing dies Redding has manufactured? I mean, if the correct answer on headspace dimensions is based on the number of chambers cut or resizing dies manufactured, then Redding would would be correct, no?

I'm not gonna argue either. Saying you're wrong isn't arguing. Simply the truth.

 

[25WSM]

280 Ackley Improved Emperical Headspace Test

Top is SAAMI or Nosler type headspace gauge for 280 AI. Bottom is the “Traditional” headspace gauge for the 280 Ackley Improved, note the difference between the shoulder angles. These C…

gunsmithtalk.wordpress.com

If nosler made the chamber to have a crush fit on a standard round and do did Ackley then they are the same. If the nosler chamber is .014 short then a factory 280 would not close on the bolt. A no go guage is .004 longer and won't close. Add another .010 and it surely won't. When I chamber one with a standard go guage used as the no go and try the Sammi no-go fits exactly the same. If you chambered up a 280ai and made it .014 short from standard no 280 brass would fit period. The .014 number comes from measuring from 2 different spots on the neck. I assure you that I have made minimum headspace 280ais using a go guage as the no go and did another with the Sammi guage and the fired brass was identical. Look at the pictures and explanation in the article. Doesn't get any simpler than that.
Shep

 

[25WSM]

Look up Reamer guy on YouTube article on the 280ai controversy. Empirical data made the video.
Conclusion is they are the same. Simple. I don't care how good at math you are. When you measure from 2 different spots on the shoulder the math doesn't work. Yes your math is correct 100% but the .014 difference is the distance between the 2 different points being measured to not the actual headspace.
The problem Redding had was that they made dies that were called 280 improved. Not Ackley improved. An improved cartridge can be anything you want it to be. An Ackley improved has to be .004 shorter than the standard cartridge. If it's not .004 short it isn't an Ackley. The nosler/Sammi chamber is .004 shorter than standard 280. Exactly the same.
Shep

 

[Pdvdh]

Thought you weren't gonna argue.

Did you mention if you've cut more chambers than resizing dies manufactured by Redding? If so, I missed it. If you call Redding to compare production numbers, it now appears you could assist them by informing them that their original 'tradtional' 280 A.I. resizing die was never correct. It was always wrong. Was never a true P.O. Ackley resizer in the first place. And that you don't care how good their design engineers are with math. They're still wrong, because you've always cut your 280 AI chambers to identical headspace dimensions, both before and after SAAMI established their specifications. And that should settle the matter, once and for all.

I won't bother to reproduce the PTG provided chamber reamer spec sheet for a 'traditional' 280 A.I., that showed the identical datum location on the shoulder as the SAAMI 280 Ackley Improved, but 0.014" greater in length. Wouldn't even generate a blink. Both shoulders are 40 degrees. It's pretty hard to misinterpret the distance from the case head to the headspace datum on the shoulder of identical 40 degree shoulders, even for a mathematician or an engineer. The distances are printed on the both spec sheets.

As to diminishing the role of math in the manufacture of chamber reamers, go-gauges, resizing dies, or the establishment of SAAMI specifications for any cartridge, pretty sure the math comes first and foremost. Even if those dirty mathematicians and engineers have never seen a metal lathe, let alone operated one.

Now to help avoid further argument, I support your 'right' to be wrong, and have no issues with you persistently employing that 'right'.

 

[25WSM]

I not arguing just stating facts that are true. I've been doing Ackley Chambers for over 30 yrs. Besides your the one saying it's wrong. I have physical proof and I've showed you 2 references that physically sHow you they are the same. I know for a fact that if you chamber a barrel with the Sammi guage and another with the standard go as a no go that those Chambers are in fact the same. How many of each have you chambered and measured. How many Ackley Reamers and guages do you own. How many different Chambers have you measured of each. Obviously none. It's ok to think your right. You looked at a print comparing an apple to an orange and your right. They are both fruit. But in the real hands on physical world they are the same depth. The only way they could be slightly off is if you use a no go on a Reamer with a different neck diameter. And that would only change it a thou of 2. Be glad to have you come to the shop and you bring your Reamer and guage and I will do 2 chambers. Sammi and an original AI. Actually I can show you 4 280ai rifles done to PO spec. What's really weird is nosler 280ai brass fits them all perfectly. They should absolutely be .014 short and then grow .014 when fired. They do not.
Really it can't get any simpler than dropping both guages into a case headspace tool and see if one is .014 different. Hard physical proof. They are not different as shown in the article and video. Wonder how they got that solid steel guage to go in that hole .014 deeper. Explain that. But your right. I'm wrong. Oh well I can't win them all. And yet you probably have never even measured one or 50 of them. Or have the tools to do so.
Shep

 

[CTK]

Now that this cartridge is popular, it is absurd that this issue continues to confuse everyone. I do not know the correct answer to the headspace question and have owned 4 280ai's. I have specified the Sammi chamber on my last 3 builds. My previous gunsmith cut the chamber too short to chamber Nosler brass. This was a famous accuracy gunsmith. Not intending to criticize him but illustrating that this confusion should have been solved a long time ago. I now use Peterson 280ai brass and the same Redding 280ai dies that I have owned for many years. I have never fire formed brass for the 280ai as it seems pointless given the availability of Nosler 280ai brass for at least 10 years.

 

[shortgrass]

Compare this print to the SAAMI print.......... Both have a measurement from the bolt face to the .375 datum on the shoulder. The SAAMI print can be found at www.saami.org

 

[dflyfish]

This is the print for the reamer we use. might be newer, but clearly points out the .014 shirt of the OG 280 AI

 

[25WSM]

Dflyfish what do you use for your headspace guage?
Shep