The .338 federal is based on the .308 win and has a C.O.A.L. Of 2.75in. compared to the .308 which is 2.800 so there will be no issue with the mag length.
But with a longer bolt gun magazine you seat the bullets out to chase the throat as the barrel wears. With SR-25/Magpul LR mags you are stuck around 2.800 and with a bolt gun you can go a touch over 3.00
Might be a fun little caliber for shooting pigs with an AR-10.
You know I like my coffee sweet in the morning
and I'm crazy about my tea at night