Here are a couple.
Heiser double loop with a 6" M&P, period correct throughout the 1st half of the 20th Century.
This holster made by Redhead is from the 1930's, similar models were popular in the 1920's.
This style was used by Heiser through the early part of the 20th Century.
Another Heiser style known as " the Citizens Favorite".
Lawrence flap holster and Heiser holster.
Pre WW II Lawrence holster.
There are a few ideas of what to look for.
Regards,
turnerriver