Hi Jakko/Ed: Looking closely at the photos, you can see 30 round magazines but this is MY observance and I stand to be corrected: The large group photo shows about 4 soldiers carrying Thompsons. 2 soldiers in the upper centre left definitely have 2 units with 30 round mags. Centre right beside the Browing 1919 is definitley a 30 round mag.
In the other photo, one soldier rests his arm on an ammo belt/pouches which look to be 30 round mags.
Thats may 2 cents on these photos. Thanks for the posting.
Robert