Help with 280 AI (sammi spec) vs 280 AI Improved 40

swift_one

swift_one

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I'm just wondering if someone could explain the difference between the difference of .014" between a Sammi spec 280AI and a non-Sammi spec 280AI.
In today's world, which one do you want to go with and I see Redding Dies acknowledge a difference and make different dies. What about the Sammi spec Nosler 280AI brass? If a guy was going to build a gun, which 280AI do you go with, sammi or non-sammi? Any clarification is much appreciated.
 
The Sammi spec 280AI is a monumental screw up. Those in 'power' thought there was a problem fire forming with the original Ackley Improved didn't know what they were doing.

Personally if you want brass with the correct designation go the Sammi spec 280AI. If you want the original version fire form your .280 brass. There really will be no difference in performance.
 
I just recently finished building a 280ai (sammi spec). I ordered the 280ai reamer and dies from Brownells and didnt really give it a second though. I later found out about the other non sammi spec version but talked to both Brownells and Redding to make sure my dies were compatible with the reamer. I was ensured that if you're buying a new reamer or dies, you wont have to worry about it being non-sammi.
 
If I was starting out today with a new build and was shopping for dies, and wanted to use "Nosler 280 Ackley Improved" brass, I would be shopping for the SAAMI spec reamer.

No fire forming, plus, I'm betting you can't find the old Redding "Rem Imp 40" dies anyways.
 
sask378 said:
If I was starting out today with a new build and was shopping for dies, and wanted to use "Nosler 280 Ackley Improved" brass, I would be shopping for the SAAMI spec reamer.

No fire forming, plus, I'm betting you can't find the old Redding "Rem Imp 40" dies anyways.
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It is my belief the reamer and dies are the same, the chamber is cut to a different head space gauge. The new version being .014" shorter in head space. Which would mean the new fully formed brass commercially available would have .014" head clearance in an old version chamber. You cannot safely use the new Nosler .280 Improved brass in a traditional Ackley chamber.
 
In the case where you have the longer chamber, could you neck up your new Nosler brass to .308, then neck it back down to .284 leaving a small shoulder in the correct spot to maintain the proper headspace? Then when fired it should form to the chamber and correct head spacing correct?
 
Cleftwynd said:
In the case where you have the longer chamber, could you neck up your new Nosler brass to .308, then neck it back down to .284 leaving a small shoulder in the correct spot to maintain the proper headspace? Then when fired it should form to the chamber and correct head spacing correct?
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If you created a false shoulder strong enough that you could feel the bolt closing on it firmly... it would fire form safely and correctly. The brass may visually indicate where the old angles were.. but I think it would work fine... of course it would no longer fit sammi chambers...
 
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