Quote Originally Posted by CFJunkie View Post
I have a short action, 10 FCP-K .308, vintage 2012, and have loaded rounds with OAL of 2.912 with room left in its Savage detachable mag.
I have a 10 FP .308 with a new barrel, vintage 2012, and have loaded rounds with OAL of 2.902 with room left in its Savage hidden mag.
The original 10 FP .308-barrel, vintage 2008, (eventually had 6,500 rounds down the barrel with the lands eroded) had been loaded late in its life to 2.960 OAL with room left in the Savage hidden mag.
At that OAL, I was having issues with maintaining repeatable neck tension with bullets seated out that far so I replaced the barrel.

I measured my Savage detachable .308 mag and its internal OAL limit is 3.020 inches.
I believe the Savage hidden mag on the 10 FP is the same length as the detachable mag (the hidden mag looks like it is just the mag body with the bottom removed) so it should have the same OAL limit.

My AICS .308 mag (aluminum) will allow about 2.895 OAL. My AICS .308 plastic mag, with an internal dimension of only 2.840, really limits seating out into the lands.

Measure the mag internal size and you'll know your mag limits.
Then you need to see what OAL will work in your barrel.

I won't talk about chamber depth, because every bullet design (even those with the same bullet weight) has a different cartridge base to Ogive length.
Your preference for jump will determine the OAL for each particular bullet you use.
Thanks CFJunkie, Thats the kind of info I was needing. Looks like 7x57 is a no go.