Your comment about the length of the M-1 leads me to believe that you are striving for accuracy as part of your project. So...

The M-1 has 5 shots to a clip, not 8 (the guy on the beachhead fires 8 before his clip clears. Also it's something to keep in mind for later: when the clip spangs out, it makes a distinctive sound as it hits the ground. The Nazis worked this out, and would wait to hear the clip clear, then attack the position. As time went on, GIs would carry an empty clip in their pocket to throw down to cause an attack when they still had a full clip.

It's not a regiment with only 31 guys. There are 3+ regiments(colonel commanding) to a division(general commanding), 4+ battalions(LTC commanding) to a regiment, 4+ companies(major commanding) to a battalion, 2+ platoons (captain commanding) to a battalion. Presumably the captain never made it off the beach, which leaves out Lieutenant in charge of the platoon. 3 10 man squads of rifleman, one of whom is assigned a BAR make up your platoon. Each squad also has at least a corporal and a sergeant assigned, and the lot has another sergeant or more above them along with usually a lieutenant per squad. Base total (including our captain) is ~41+ people. Pick them off on the beach to bring it down to what you plan on, but that should give you an idea on where to start.

Looks promising, good luck with it.