Quite a few of us recently picked up Mauser M12 Extremes in .308, with the 20" barrel, for a smoking deal. We've been sharing some handloading lessons learned over on this thread,
Mauser M12 Extreme Opinions
but figured it's time to start a dedicated thread for this subject.
One thing that will help us rate the potential to share our data is information about our individual chambers, so we can get a feel for how consistent they are. Being production firearms, I would guess their chambers are finished with reamers that cut the throat in the same operation, so I am hoping we'll find them consistent in that dimension. Those of us who compared serial numbers found them to be close together so hopefully they're from a single production run.
Here are the Max OALs (bullet just lightly pressed into the lands such that it does not fall out when the muzzle is vertical) I measured for mine:

Nosler 165 BT, 165 AB, and 150 BT - 2.935"
Nosler 150 Part - 2.92" - 2.93" depending on the state of the exposed lead tip
Nosler 150 AB - 2.95"
Nosler 168 ABLR - 2.97"
Nosler 168 HPBT - 2.90"
165 Sierra Game King (probably 25-30 years old) - 2.90"
168 Sierra MK HPBT - 2.89"

What have others found in their measurements?

I'll post some data later when I get the time - I have yet to find "the load" I want. My goal is a load with a good hunting bullet in the 165 grain class (though 150 would be ok too) that will consistently shoot MOA or less and produce 2700 FPS from the 20" barrel, ideally with a powder that is pretty temperature resistant.
Up to now I have been concentrating on loads that will also fit in the ~ 2.85" OAL limitation of my magazine, but I have a Sauer 100 magazine (interchangeable) in 6.5x55 length inbound which will remove that limitation - should hold up to at least 3.2" OAL.

Looking forward to collaborating on some good loads for these fine rifles.

Cheers,
Rex