Re: 280 Ackley Improved Build
I've researched the supposed difference in the "two" 280 AI chamberings and I have come to the conclusion that there is no difference.
While I can't find the info when I need it (like now!), the difference in the drawings by the SAAMI guys are really a matter of semantics. I believe they are taking the measurements differently and if I recall correctly (maybe a long shot!) it has to do with the way a factory .280 gauge contacts the ackley chamber as opposed to taking the measurement off a SAAMI ackley 40* gauge (?) but the end result is that there is no difference. Again, I could be wrong with my recollection here. Just trying to give an idea what may be going on.
Here is a link to a good comparison of the SAAMI and the original AI gauges on youtube. Read the text under the video. -
http://www.youtube.com/watch?v=Vlskn2CE7-Y
Here is a post from ricksmith on 24hourcampfire -
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.
Here's another post you need to scroll to the bottom.
http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/5061125/3
There is still some very good info that clearly explains the reason for the apparent difference in the drawings and why there really isn't any practical difference. If I run across it I will add it.
I think you should be good to go with either the original AI or the SAAMI AI from what I have seen once I dug a little deeper.
I think I would like to build one someday. I hope you enjoy yours.
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<span style="font-weight: bold">Ha! Found it! </span></span> It goes along with the youtube video but is more detailed.
https://gunsmithtalk.wordpress.com/2012/07/17/280-ackley-improved-emperical-headspace-test/