The Use of Wood Bullet Blanks is very rare these days in Film production, for Safety reasons and "Public Liability."
In former years, 1950s and 60s, such things were done without too much “touchy-feely” Restrictions.
So the specific production of “Full profile” Blanks for specific MG use (Both Lewis and Brens Require a Full Profile Blank to function properly in feeding. ) was essential. The Cheapest way was to use the existing Mk10 design of wood bullet blank.
These days, we use Extended (or Long) Brass Blank, or “Plastic” Blank, for these Guns in Films…the Vickers can use Normal Blanks ( short or Ball case) with a Feed Block discriminator, or use Full length Blanks without discriminator. AVB-FOS makes its own “Long Blanks” in any calibre, by inserting an Internal-Case-diameter Brass Tube into a cylindrical Ball case, then Forming down to correct Case-Bullet profile. See “Beneath Hill 60” for successful use of this method in Lewis Guns and Maxims/Vickers.
BTW, for many years, the PLA Film Unit ( Studio August One “Ba-Yi”) used Ball ammo in its films about the China-Japan War and Revolution…They had the Guns, and tons of Japanese & Chinese Ammo left from the War and Korea, and the “Extras” were PLA troops. All the scenes with Guns firing were done in particular way ( offset to side) to permit safe use of Ball ammo.
Nowadays, only Blanks are used, but not with the expertise one expects from “Western” made Films. ( a Lot of CGI is used as well.)
Although, they are improving…a Film “Assembly” ( Revolution period, 1948) was made in 2005, with everything one would expect in a “Western” well-made film ( correct rifles, MGs, Tanks, Japanese Artillery, and correct Blank firing…even a Johnson M1941 Rifle in Blank fire, a very difficult thing to achieve, technically. ( only Johnsons seen before in BF, was in a very early “Dr.Who” episode back in the 1970s…guns probably supplied by Bapty’s of London.)
AV Ballistics Film Ordnance Services