Quote Originally Posted by Luke45 View Post
buts its not the sammi version, im not sure if they use the same gauge or not though, mine is set for a 4 thou further back from a standard 280
The .004" you speak of is from the casehead to the shoulder-neck junction. Its the "Correct" way head clearance is established using the parent cartridge in an improved chamber with a .004" crush fit for firing/forming.


There's a conversely if there is a difference between the SAAMI and the traditional Ackley version. Some say they're different, others say they're the same. I don't know one way or the other. My better 280s are the traditional Ackley versions.

http://gunsmithtalk.wordpress.com/20...mproved-alert/

but.....
https://gunsmithtalk.wordpress.com/2...eadspace-test/

...and
http://www.redding-reloading.com/tec...80-changes%29:

Bill