The CIP long action mag for the 338 Lapua/300 Norma family is different than that for the 300 WM family. Both mags will work in the long action Coup.
Non-CIP lengths mags will probably work as well so long as your chassis or stock is designed for them. Our long action Xylo chassis is designed for CIP length mags only.
The current short action Coup is a target action and will not work with BDL boxes. A lightweight hunting option is forthcoming and will be tested with BDL boxes. We'll know how well it works or doesn't after testing.
Accurate Mag makes short action mags for the WSM and SAUM family of cartridges that will work with the short Coup.
https://accurate-mag.com/shop/magazines/300-winchester-short-magnum-dssf-magazine/
Frame of the Hawkins short action DBM in will interfere with the trigger hanger, said frame can be modified to provide clearance without difficulty.
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